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Homonyms

IRMNG homonym list - genus level - Initial letter = "O" (1027)

Please note, this is a provisional homonyms list from IRMNG on 2019-11-22, and is subject to change. It may include nomina nuda, rejected and otherwise non-current names, plus some published misspellings, in addition to homonyms that have been validly published. A small proportion of duplicate entries awaiting rationalisation may also be included.

Click on any genus name for additional details, as currently available.

Oakesia
 Oakesia S. Watson, 1879 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Liliales (Order) > Liliaceae (Family)
     Oakesia Tuckerman in W.J. Hooker, 1842 accepted as Oakesia Tuckerman in W.J. Hooker, 1842 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Ericales (Order) > Ericaceae (Family)

Oar
     Oar Prout in Seitz, 1913 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
     Oar Semenov-Tyan-Shanskii, 1954 accepted as Oar Semenov-Tyan-Shanskii, 1954 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Chrysididae (Family)

Oaristes
     Oaristes Helava in Helava, Howden & Ritchie, 1985 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Histeridae (Family)
     Oaristes Fennah, 1964 accepted as Oaristes Fennah, 1964 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)

Obba
     Obba Tosquinet, 1896 accepted as Obba Tosquinet, 1896 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Ichneumonidae (Family)
     Obba Walker in Chapman, 1869 accepted as Obba Walker in Chapman, 1869 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Obba Beck, 1837 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Camaenidae (Family)

Obbinula
     Obbinula Stache, 1880 † accepted as Obbinula Stache, 1880 † · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Obbinula Stache, 1889 † accepted as Obbinula Stache, 1889 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Obelaria
     Obelaria Hartlaub, 1897 accepted as Obelaria Hartlaub, 1897 (unassessed) · Animalia (Kingdom) > Cnidaria (Phylum) > Cnidaria (awaiting allocation) (Class) > Cnidaria (awaiting allocation) (Order) > Cnidaria (awaiting allocation) (Family)
 Obelaria Haeckel, 1879 accepted as Obelia Péron & Lesueur, 1810 (synonym) · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Leptothecata (Order) > Campanulariidae (Family)

Obelia
     Obelia Lamouroux, 1821 accepted as Obelia Lamouroux, 1821 (unassessed) · Animalia (Kingdom) > Bryozoa (Phylum) > Bryozoa (awaiting allocation) (Class) > Bryozoa (awaiting allocation) (Order) > Bryozoa (awaiting allocation) (Family)
     Obelia Péron & Lesueur, 1810 · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Leptothecata (Order) > Campanulariidae (Family)
 Obelia Hartlaub, 1897 accepted as Hartlaubella Poche, 1914 · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Leptothecata (Order) > Campanulariidae (Family)

Obeliscus
     Obeliscus Li, 2002 accepted as Obeliscus Li, 2002 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Psocoptera (Order) > Psocoptera (awaiting allocation) (Family)
     Obeliscus Agassiz, 1845 accepted as Obeliscus Agassiz, 1845 · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Obeliscus Popofsky, 1913 † accepted as Obeliscus Popofsky, 1913 † (unassessed) · Protozoa (Kingdom) > (Phylum) > (Class) > (Order) > Protozoa (awaiting allocation) (Family)
 Obeliscus Graybill, 1923 accepted as Obeliscoides Graybill, 1924 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Rhabditida (Order) > Trichostrongylidae (Family)
 Obeliscus Anonymous, 1797 accepted as Pyramidella Lamarck, 1799 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)
 Obeliscus Gray, 1847 accepted as Pyramidella Lamarck, 1799 (junior objective synonym of Pyramidella) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)
     Obeliscus Beck, 1837 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Subulinidae (Family)

Obelura
     Obelura Burr, 1907 accepted as Obelura Burr, 1907 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Dermaptera (Order) > Dermaptera (awaiting allocation) (Family)
 Obelura Warren, 1908 accepted as Novobelura Shaffer & Nielsen, 1996 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Thyrididae (Family)

Oberea
     Oberea Mulsant, 1839 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Oberea Dejean, 1835 accepted as Oberea Mulsant, 1839 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Oberonia
     Oberonia Lindley, 1830 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Oberonia Bethune-Baker, 1909 accepted as Oboronia Karsch, 1893 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lycaenidae (Family)

Oberprieleria
     Oberprieleria Alonso-Zarazaga & Lyal, 1999 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Oberprieleria Cooper & Cooper, 2002 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Saturniidae (Family)

Oberthueria
     Oberthueria Vuillet, 1911 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
     Oberthueria Staudinger in Romanoff, 1892 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Bombycidae (Family)
 Oberthueria Leech, 1897 accepted as Parabraxas Leech, 1897 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Epicopeiidae (Family)

Oberthuria
 Oberthuria Vuillet, 1911 accepted as Oberthueria Vuillet, 1911 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Oberthuria Leech, 1897 accepted as Parabraxas Leech, 1897 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Epicopeiidae (Family)
 Oberthuria Staudinger in Romanoff, 1892 accepted as Oberthueria Staudinger in Romanoff, 1892 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Bombycidae (Family)

Oberthüria
 Oberthüria Staudinger in Romanoff, 1892 accepted as Oberthueria Staudinger in Romanoff, 1892 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Bombycidae (Family)
 Oberthüria Leech, 1897 accepted as Parabraxas Leech, 1897 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Epicopeiidae (Family)
 Oberthüria Vuillet, 1911 accepted as Oberthueria Vuillet, 1911 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Obex
 Obex Iredale, 1925 accepted as Colubraria Schumacher, 1817 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Neogastropoda (Order) > Colubrariidae (Family)
 Obex Laws, 1940 accepted as Obexomia Laws, 1941 (non Iredale, 1925) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)

Obliquostoma
     Obliquostoma Foissner, Agatha & Berger, 2002 · Chromista (Kingdom) > Ciliophora (Phylum) > Colpodea (Class) > Colpodida (Order) > Exocolpodidae (Family)
     Obliquostoma Thoelen, 1968 † · Animalia (Kingdom) > Bryozoa (Phylum) > Gymnolaemata (Class) > Cheilostomatida (Order) > Cheilostomatida (awaiting allocation) (Family)

Obolaria
     Obolaria Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Gentianaceae (Family)
 Obolaria O. Kuntze, 1891 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Dipsacales (Order) > Caprifoliaceae (Family)

Obrima
     Obrima Walker, 1856 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
 Obrima Simon, 1894 accepted as Obrimona Strand, 1934 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Linyphiidae (Family)

Obriomorpha
     Obriomorpha Aurivillius, 1917 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Obriomorpha Matsushita, 1933 accepted as Pseudiphra Gressitt, 1935 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Obrium
     Obrium Leconte, 1824 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Obrium Dejean, 1821 accepted as Obrium Leconte, 1824 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Obrussa
     Obrussa Heyden in Saalmueller, 1891 accepted as Obrussa Heyden in Saalmueller, 1891 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
     Obrussa Braun, 1915 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Nepticulidae (Family)
 Obrussa Iredale, 1925 accepted as Obrussena Iredale, 1930 (Invalid: junior homonym of Obrussa Braun, 1915 [Lepidoptera]; Obrussena is a replacement name) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Acteonidae (Family)

Obscura
     Obscura Wagner, 1897 accepted as Obscura Wagner, 1897 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Obscura Mohrig, 2003 accepted as Obscura Mohrig, 2003 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Sciaridae (Family)
     Obscura Fibiger, 2010 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Micronoctuidae (Family)

Obscurella
     Obscurella Baranov, 1991 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Rhynchonellata (Class) > Rhynchonellida (Order) > Ancistrorhynchidae (Family)
     Obscurella Clessin, 1889 accepted as Obscurella Clessin, 1889 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Architaenioglossa (Order) > Cyclophoridae (Family)
 Obscurella Vassiljeva, 1990 † accepted as Obscurania Devaere, Clausen & Steiner in Devaere, Clausen, Steiner, Álvaro & Vachard, 2013 † (junior homonym) · Animalia (Kingdom) > Mollusca (Phylum) > Helcionelloida (Class) > Helcionelliformes (Order) > Helcionelloidea (awaiting allocation) (Family)

Ocalea
     Ocalea Erichson, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
     Ocalea Robineau-Desvoidy, 1863 accepted as Ocalea Robineau-Desvoidy, 1863 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Diptera (awaiting allocation) (Family)

Ocana
     Ocana Hebard, 1927 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tettigoniidae (Family)
 Ocana H. Adams, 1861 accepted as Sarmaticus Gray, 1847 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Vetigastropoda (Order) > Turbinidae (Family)

Occidentalia
     Occidentalia Dyar & Henrich, 1927 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Pyralidae (Family)
     Occidentalia Miller, 1971 † accepted as Occidentalia Miller, 1971 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Pterosauria (Order) > Pterosauria (awaiting allocation) (Family)

Occultitermes
     Occultitermes Emerson, 1960 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Blattodea (Order) > Termitidae (Family)
     Occultitermes Emerson, 1955 accepted as Occultitermes Emerson, 1960 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Blattodea (Order) > Termitidae (Family)

Oceana
 Oceana Gray, 1848 accepted as Oceana Gray, 1848 (Misspelling) · Animalia (Kingdom) > Cnidaria (Phylum) > Cnidaria (awaiting allocation) (Class) > Cnidaria (awaiting allocation) (Order) > Cnidaria (awaiting allocation) (Family)
 Oceana Hall, 1867 accepted as Oceana Hall, 1867 (Misspelling) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Vetigastropoda (Order) > Turbinidae (Family)

Oceania
     Oceania Kölliker, 1853 · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Anthoathecata (Order) > Oceaniidae (Family)
 Oceania Reichenbach, 1828 accepted as Oceania Reichenbach, 1828 (Misspelling) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Oceania Péron & Lesueur, 1810 accepted as Oceania Péron & Lesueur, 1810 (unassessed) · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Anthoathecata (Order) > Oceaniidae (Family)

Oceanites
     Oceanites Keyserling & Blasius, 1840 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Procellariiformes (Order) > Hydrobatidae (Family)
 Oceanites J. Kohlmeyer, 1977 accepted as Oceanitis J. Kohlmeyer, 1977 (misspelling) · Fungi (Kingdom) > Ascomycota (Phylum) > Sordariomycetes (Class) > Microascales (Order) > Halosphaeriaceae (Family)

Oceanitis
 Oceanitis Bonaparte, 1854 accepted as Oceanites Keyserling & Blasius, 1840 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Procellariiformes (Order) > Procellariidae (Family)
     Oceanitis J. Kohlmeyer, 1977 · Fungi (Kingdom) > Ascomycota (Phylum) > Sordariomycetes (Class) > Microascales (Order) > Halosphaeriaceae (Family)

Oceanus
     Oceanus Montfort, 1808 accepted as Oceanus Montfort, 1808 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Oceanus Koch, 1816 accepted as Stercorarius Brisson, 1760 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Ciconiiformes (Order) > Laridae (Family)
 Oceanus De Haan in Siebold, 1833 accepted as Charybdis De Haan in Siebold, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Portunidae (Family)

Ocella
     Ocella Evans, 1953 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Hesperiidae (Family)
 Ocella Jordan & Hubbs, 1925 accepted as Occella Jordan & Hubbs, 1925 (misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Scorpaeniformes (Order) > Agonidae (Family)

Ocellaria
     Ocellaria (Tulasne & C. Tulasne) Kirschstein, 1935 · Fungi (Kingdom) > Ascomycota (Phylum) > Leotiomycetes (Class) > Helotiales (Order) > Sclerotiniaceae (Family)
     Ocellaria Ramond, 1801 † · Animalia (Kingdom) > Porifera (Phylum) > Demospongea (Class) > Lithistida (Order) > Lithistida (awaiting allocation) (Family)
 Ocellaria (L.R. Tulasne & C. Tulasne) P.A. Karsten, 1871 accepted as Pezicula L.R. Tulasne & C. Tulasne, 1865 · Fungi (Kingdom) > Ascomycota (Phylum) > Leotiomycetes (Class) > Helotiales (Order) > Dermateaceae (Family)
 Ocellaria Weinkauff, 1881 accepted as Erosaria Troschel, 1863 (invalid: junior homonym of Ocellaria Ramond, 1801 [Porifera]) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Littorinimorpha (Order) > Cypraeidae (Family)

Ochina
     Ochina Stephens, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Ptinidae (Family)
     Ochina Stephens, 1829 accepted as Ochina Stephens, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Ptinidae (Family)
     Ochina Dejean, 1821 accepted as Ochina Stephens, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Ptinidae (Family)

Ochlerus
     Ochlerus Spinola, 1837 accepted as Ochlerus Spinola, 1837 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Ochlerus Gistl, 1848 accepted as Ochlerus Gistl, 1848 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)

Ochodaeus
     Ochodaeus Serville, 1825 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Ochodaeus Dejean, 1821 accepted as Ochodaeus Serville, 1825 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Ochralea
 Ochralea Chevrolat, 1837 accepted as Oides Weber, 1801 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Ochralea Dejean, 1835 accepted as Monolepta Erichson, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
 Ochralea Clark, 1865 accepted as Monolepta Chevrolat, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Ochresthes
 Ochresthes Lacordaire, 1869 accepted as Ochraethes Chevrolat, 1860 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Ochresthes Bates, 1880 accepted as Ochraethes Chevrolat, 1860 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Ochrogaster
     Ochrogaster Herrich-Schäffer, 1856 accepted as Ochrogaster Herrich-Schäffer, 1856 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Notodontidae (Family)
     Ochrogaster Felder, 1874 accepted as Ochrogaster Felder, 1874 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Eupterotidae (Family)

Ochrosoma
     Ochrosoma Herrich-Schäffer, 1856 accepted as Ochrosoma Herrich-Schäffer, 1856 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
 Ochrosoma Ogloblin, 1930 accepted as Ogloblinia Csiki, 1939 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Ochrosphaera
     Ochrosphaera Schussnig, 1930 · Chromista (Kingdom) > Haptophyta (Phylum) > Coccolithophyceae (Class) > Coccosphaerales (Order) > Hymenomonadaceae (Family)
     Ochrosphaera Sawada, 1959 · Fungi (Kingdom) > Ascomycota (Phylum) > Ascomycota incertae sedis (Class) > Ascomycota incertae sedis (Order) > Ascomycota incertae sedis (Family)

Ochrus
     Ochrus Lacordaire, 1869 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Ochrus P. Miller, 1754 accepted as Ochrus P. Miller, 1754 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)

Ochryopus
 Ochryopus Chaudoir, 1855 accepted as Neochryopus Bänninger, 1931 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Ochryopus accepted as Ochyropus Schiödte, 1847 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Ochtebiites
     Ochtebiites Ponomarenko, 1977 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Hydraenidae (Family)
     Ochtebiites Ponomarenko, 1977 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera incertae sedis (Family)

Ochthenomus
     Ochthenomus Dejean, 1834 accepted as Ochthenomus Dejean, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Anthicidae (Family)
 Ochthenomus Schmidt, 1842 accepted as Endomia Laporte in Brullé, 1840 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Anthicidae (Family)

Ochthephila
     Ochthephila Beck, 1837 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Helicidae (Family)
 Ochthephila Westwood, 1840 accepted as Ochtiphila Fallén, 1823 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Chamaemyiidae (Family)

Ochthephilus
     Ochthephilus J. Wurdack in B. Maguire et al., 1972 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Myrtales (Order) > Melastomataceae (Family)
     Ochthephilus Mulsant & Rey, 1856 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
 Ochthephilus Nietner, 1857 accepted as Perileptus Schaum in Erichson, 1860 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Ochthera
     Ochthera Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Ephydridae (Family)
 Ochthera Bergroth, 1890 accepted as Ochterus Latreille, 1807 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Ochteridae (Family)

Ocneropsis
     Ocneropsis Uvarov, 1942 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Pamphagidae (Family)
 Ocneropsis Kozhanchikov, 1950 accepted as Gissarus Nye in Watson, Fletcher & Nye, 1980 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lymantriidae (Family)

Ocnophila
     Ocnophila Brunner in Brunner & Redtenbacher, 1907 accepted as Ocnophila Brunner in Brunner & Redtenbacher, 1907 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Orthoptera (awaiting allocation) (Family)
 Ocnophila Meyrick, 1926 accepted as Ocnophilella Fletcher, 1940 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Tineidae (Family)

Ocnus
     Ocnus Forbes & Goodsir in Forbes, 1841 · Animalia (Kingdom) > Echinodermata (Phylum) > Holothuroidea (Class) > Dendrochirotida (Order) > Cucumariidae (Family)
 Ocnus Clark, 1865 accepted as Ocnida Lefèvre, 1885 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Ocoa
     Ocoa Lane, 1970 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Ocoa Yeates, Irwin & Wiegmann, 2003 accepted as Evocoa Yeates, Irwin & Wiegmann, 2006 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Evocoidae (Family)

Ocrisia
     Ocrisia Séguy in Townsend, 1935 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Calliphoridae (Family)
     Ocrisia Ragonot in Romanoff, 1893 accepted as Ocrisia Ragonot in Romanoff, 1893 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)

Ocromis
     Ocromis Kirsch, 1889 accepted as Ocromis Kirsch, 1889 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
 Ocromis Sharp, 1890 accepted as Listroderes Schoenherr, 1826 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Octactis
     Octactis J.Schiller, 1925 · Chromista (Kingdom) > Ochrophyta (Phylum) > Dictyochophyceae (Class) > Dictyochales (Order) > Dictyochaceae (Family)
     Octactis Schultze, 1760 accepted as Octactis Schultze, 1760 (unassessed) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinodermata (awaiting allocation) (Class) > Echinodermata (awaiting allocation) (Order) > Echinodermata (awaiting allocation) (Family)

Octadenia
     Octadenia Shileiko, 1978 accepted as Octadenia Shileiko, 1978 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Gastropoda (awaiting allocation) (Order) > Gastropoda (awaiting allocation) (Family)
     Octadenia R. Brown ex F.E.L. Fischer & C.A. Meyer, 1837 accepted as Octadenia R. Brown ex F.E.L. Fischer & C.A. Meyer, 1837 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Brassicales (Order) > Brassicaceae (Family)

Octalobus
 Octalobus Elliot, 1883 accepted as Felis Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Felidae (Family)
 Octalobus Elliot, 1881 accepted as Felis Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Felidae (Family)

Octavia
     Octavia Bigot, 1854 accepted as Octavia Bigot, 1854 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Diptera (awaiting allocation) (Family)
 Octavia Thomson, 1860 accepted as Eroschema Pascoe, 1859 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Octavia A.P. de Candolle, 1830 accepted as Lasianthus W. Jack, 1823 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Rubiaceae (Family)

Octella
     Octella Rafinesque, 1838 accepted as Octella Rafinesque, 1838 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Myrtales (Order) > Melastomataceae (Family)
 Octella Forel, 1915 accepted as Oligomyrmex Mayr, 1867 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Formicidae (Family)

Octobothrium
     Octobothrium Diesing, 1850 accepted as Octobothrium Diesing, 1850 (unassessed) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Cestoda (Class) > Cestoda (awaiting allocation) (Order) > Cestoda (awaiting allocation) (Family)
 Octobothrium Leuckart, 1827 accepted as Mazocraes Hermann, 1782 (synonym) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Chimaericolidea (Order) > Chimaericolidae (Family)

Octocotyle
     Octocotyle Chiaje, 1841 accepted as Octocotyle Chiaje, 1841 (unassessed) · Animalia (Kingdom) > Animalia (awaiting allocation) (Phylum) > Animalia (awaiting allocation) (Class) > Animalia (awaiting allocation) (Order) > Animalia (awaiting allocation) (Family)
 Octocotyle Diesing, 1850 accepted as Mazocraes Hermann, 1782 (synonym) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Mazocraeidea (Order) > Mazocraeidae (Family)

Octocynodon
     Octocynodon Broom, 1940 † accepted as Octocynodon Broom, 1940 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)
 Octocynodon Fowler, 1904 accepted as Halichoeres Rüppell, 1835 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Labridae (Family)

Octodon
     Octodon Lansberge, 1874 accepted as Octodon Lansberge, 1874 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Octodon Bennett, 1832 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Octodontidae (Family)
 Octodon P. Thonning in H.C.F. Schumacher, 1827 accepted as Spermacoce Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Rubiaceae (Family)

Octogomphus
 Octogomphus Broom, 1932 † accepted as Octogomphus Broom, 1932 † (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)
     Octogomphus Selys, 1873 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Odonata (Order) > Gomphidae (Family)

Octogonia
     Octogonia Müller, 1852 accepted as Octogonia Müller, 1852 · Animalia (Kingdom) > Cnidaria (Phylum) > Cnidaria (awaiting allocation) (Class) > Cnidaria (awaiting allocation) (Order) > Cnidaria (awaiting allocation) (Family)
     Octogonia Müller, 1854 accepted as Octogonia Müller, 1854 (unassessed) · Animalia (Kingdom) > Cnidaria (Phylum) > Cnidaria (awaiting allocation) (Class) > Cnidaria (awaiting allocation) (Order) > Cnidaria (awaiting allocation) (Family)
     Octogonia Klotzsch, 1838 accepted as Octogonia Klotzsch, 1838 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Ericales (Order) > Ericaceae (Family)

Octolasium
     Octolasium Omodeo, 1952 accepted as Octolasium Omodeo, 1952 (unassessed) · Animalia (Kingdom) > Annelida (Phylum) > Oligochaeta (Class) > Oligochaeta (awaiting allocation) (Order) > Oligochaeta (awaiting allocation) (Family)
     Octolasium Omodeo, 1956 accepted as Octolasium Omodeo, 1956 (unassessed) · Animalia (Kingdom) > Annelida (Phylum) > Oligochaeta (Class) > Oligochaeta (awaiting allocation) (Order) > Oligochaeta (awaiting allocation) (Family)
 Octolasium Michaelsen, 1900 accepted as Octolasion Örley, 1885 · Animalia (Kingdom) > Annelida (Phylum) > Oligochaeta (Class) > Haplotaxida (Order) > Lumbricidae (Family)

Octolobus
     Octolobus Welwitsch, 1869 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malvales (Order) > Malvaceae (Family)
 Octolobus accepted as Felis Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Felidae (Family)

Octomeria
     Octomeria R. Brown in W.T. Aiton, 1813 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Octomeria L.K.G. Pfeiffer, 1874 accepted as Otomeria Bentham in W.J. Hooker, 1849 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Rubiaceae (Family)

Octomeris
     Octomeris Sowerby, 1825 · Animalia (Kingdom) > Arthropoda (Phylum) > Maxillopoda (Class) > Sessilia (Order) > Chthamalidae (Family)
     Octomeris Naudin, 1845 accepted as Octomeris Naudin, 1845 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Myrtales (Order) > Melastomataceae (Family)

Octomys
     Octomys Thomas, 1920 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Octodontidae (Family)
 Octomys Sody, 1941 accepted as Rattus Fischer de Waldheim, 1803 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Muridae (Family)

Octonema
     Octonema Haeckel, 1879 accepted as Octonema Haeckel, 1879 (unassessed) · Animalia (Kingdom) > Cnidaria (Phylum) > Cnidaria (awaiting allocation) (Class) > Cnidaria (awaiting allocation) (Order) > Cnidaria (awaiting allocation) (Family)
 Octonema Herzenstein in Herzenstein & Warpachowski, 1888 accepted as Lefua Herzenstein, 1888 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cypriniformes (Order) > Nemacheilidae (Family)
 Octonema Martens, 1868 accepted as Oreonectes Günther, 1868 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cypriniformes (Order) > Nemacheilidae (Family)

Octopleura
 Octopleura Spruce ex Progel in C.F.P. Martius, 1865 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Gentianaceae (Family)
 Octopleura Grisebach, 1860 accepted as Ossaea A.P. de Candolle, 1828 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Myrtales (Order) > Melastomataceae (Family)

Octospora
     Octospora J. Hedwig, 1789 · Fungi (Kingdom) > Ascomycota (Phylum) > Pezizomycetes (Class) > Pezizales (Order) > Pyronemataceae (Family)
     Octospora Flu, 1911 · Protozoa (Kingdom) > Microsporidia (Phylum) > Minisporea (Class) > Microsporida (Order) > Pseudopleistophoridae (Family)

Octosporella
     Octosporella P. Döbbeler, 1980 · Fungi (Kingdom) > Ascomycota (Phylum) > Pezizomycetes (Class) > Pezizales (Order) > Pyronemataceae (Family)
     Octosporella Ray & Raghavachari, 1942 · Chromista (Kingdom) > Miozoa (Phylum) > Coccidiomorphea (Class) > Eimeriida (Order) > Eimeriidae (Family)

Octostoma
     Octostoma Otto, 1823 accepted as Octostoma Otto, 1823 (unassessed) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Trematoda (awaiting allocation) (Order) > Trematoda (awaiting allocation) (Family)
     Octostoma Kuhn, 1830 accepted as Octostoma Kuhn, 1830 (unassessed) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Trematoda (awaiting allocation) (Order) > Trematoda (awaiting allocation) (Family)

Octotheca
 Octotheca Guthörl, 1953 † accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Marattiales (Order) > Marattiaceae (Family)
 Octotheca Viguier, 1906 accepted as Schefflera J.R. Forster & J.G.A. Forster, 1775 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Apiales (Order) > Araliaceae (Family)

Octotoma
     Octotoma Guérin-Ménéville, 1844 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Octotoma Sturm, 1826 accepted as Cryptoderma Ritsema, 1885 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Octotoma Dejean, 1835 accepted as Octotoma Guérin-Ménéville, 1844 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Ocularia
     Ocularia E.J. Quekett, 1844 · Chromista (Kingdom) > Ochrophyta (Phylum) > Bacillariophyceae (Class) > (Order) > Bacillariophyceae incertae sedis (Family)
     Ocularia Jordan, 1894 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Oculeus
     Oculeus Poletaeva & Romanenko, 1970 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Ptychopariida (Order) > Ptychopariida (awaiting allocation) (Family)
 Oculeus Commerson in Lacepède, 1803 accepted as Megalops Lacepède, 1803 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Elopiformes (Order) > Megalopidae (Family)

Oculina
     Oculina Lamarck, 1816 · Animalia (Kingdom) > Cnidaria (Phylum) > Anthozoa (Class) > Scleractinia (Order) > Oculinidae (Family)
 Oculina Kubler & Zwingli, 1866 † accepted as Ophthalmidium Kubler & Zwingli, 1870 (Junior homonym of Oculina Lamarck, 1816) · Chromista (Kingdom) > Retaria (Phylum) > Tubothalamea (Class) > Miliolida (Order) > Ophthalmidiidae (Family)

Oculocornia
     Oculocornia Oliger, 1985 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Linyphiidae (Family)
     Oculocornia Wei, 1997 accepted as Oculocornia Wei, 1997 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Tenthredinidae (Family)

Oculozomus
     Oculozomus Reddell & Cokendolpher, 1995 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Schizomida (Order) > Hubbardiidae (Family)
     Oculozomus Reddell & Cokendolpher, 1995 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Schizomida (Order) > Hubbardiidae (Family)

Ocydromus
     Ocydromus Wagler, 1830 accepted as Ocydromus Wagler, 1830 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Gruiformes (Order) > Rallidae (Family)
     Ocydromus Dejean, 1836 accepted as Ocydromus Dejean, 1836 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Ocydromus Schellenberg, 1806 accepted as Bembidion Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Ocydromus Laferté-Sénectère, 1851 accepted as Chlaenius Bonelli, 1810 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Ocydromus Netolitzky, 1910 accepted as Bembidion Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Ocypete
     Ocypete Rafinesque, 1815 accepted as Ocypete Rafinesque, 1815 · Animalia (Kingdom) > Arthropoda (Phylum) > Crustacea (awaiting allocation) (Class) > Crustacea (awaiting allocation) (Order) > Crustacea (awaiting allocation) (Family)
     Ocypete Leach, 1814 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Actinedida (Order) > Trombidiidae (Family)
     Ocypete Koch, 1836 accepted as Ocypete Koch, 1836 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Araneae (awaiting allocation) (Family)

Ocypetes
     Ocypetes Wagler, 1829 accepted as Ocypetes Wagler, 1829 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Ocypetes Risso, 1826 accepted as Ocypetes Risso, 1826 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Arachnida (awaiting allocation) (Order) > Arachnida (awaiting allocation) (Family)
     Ocypetes Saunders, 1871 accepted as Ocypetes Saunders, 1871 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Buprestidae (Family)
 Ocypetes Thomson, 1878 accepted as Tylauchenia Burmeister, 1872 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Buprestidae (Family)
 Ocypetes Lesson, 1842 accepted as Murina Gray, 1842 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Chiroptera (Order) > Vespertilionidae (Family)

Ocyplanus
     Ocyplanus De Vis, 1905 † accepted as Ocyplanus De Vis, 1905 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Ocyplanus Fauvel, 1899 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)

Ocyptera
     Ocyptera Latreille, 1804 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Tachinidae (Family)
     Ocyptera Robineau-Desvoidy, 1830 accepted as Ocyptera Robineau-Desvoidy, 1830 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Diptera (awaiting allocation) (Family)

Ocypteryx
     Ocypteryx Townsend, 1931 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Tachinidae (Family)
 Ocypteryx Leach, 1817 accepted as Ocyptera Latreille, 1804 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Tachinidae (Family)

Ocypus
     Ocypus Samouelle, 1819 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
 Ocypus Gistl, 1838 accepted as Pleuracanthus Gray, 1832 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Ocypus Montrouzier, 1861 accepted as Coridromius Signoret, 1862 (junior homonym) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Miridae (Family)

Ocyris
     Ocyris Hodgson, 1845 accepted as Ocyris Hodgson, 1845 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Ocyris Hodgson, 1844 accepted as Ocyris Hodgson, 1844 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Ocyroe
     Ocyroe Péron & Lesueur, 1810 accepted as Ocyroe Péron & Lesueur, 1810 (unassessed) · Animalia (Kingdom) > Cnidaria (Phylum) > Scyphozoa (Class) > Scyphozoa (awaiting allocation) (Order) > Scyphozoa (awaiting allocation) (Family)
 Ocyroe Rang, 1828 accepted as Ocyropsis Mayer, 1912 · Animalia (Kingdom) > Ctenophora (Phylum) > Tentaculata (Class) > Lobata (Order) > Ocyropsidae (Family)
 Ocyroe R.A. Philippi, 1891 accepted as Nardophyllum (W.J. Hooker & Arnott) W.J. Hooker & Arnott in W.J. Hooker, 1836 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)

Ocys
     Ocys Stephens, 1828 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
     Ocys Gistl, 1834 accepted as Cordalia Jacobs, 1924 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
 Ocys Gistl, 1848 accepted as Bembidion Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Ocythoe
     Ocythoe Rafinesque, 1814 · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Octopoda (Order) > Ocythoidae (Family)
     Ocythoe Laporte in Brullé, 1840 accepted as Ocythoe Laporte in Brullé, 1840 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)

Oda
 Oda Monterosato, 1901 accepted as Noemiamea de Folin, 1886 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)
 Oda Ris, 1909 accepted as Risiophlebia Cowley, 1934 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Odonata (Order) > Libellulidae (Family)

Odacantha
     Odacantha Paykull, 1798 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Odacantha Perty, 1830-1834 accepted as Leptotrachelus Latreille in Cuvier, 1829 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Odacanthina
     Odacanthina Csiki, 1932 accepted as Odacanthina Csiki, 1932 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Odacanthina Liebke, 1938 accepted as Colliuris de Geer, 1774 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Odax
     Odax Valenciennes in Cuvier & Valenciennes, 1840 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Odacidae (Family)
 Odax Commerson in Lacepède, 1801 accepted as Scarus Forsskål, 1775 (synonym) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Scaridae (Family)

Odhneria
     Odhneria Travassos, 1921 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Plagiorchiida (Order) > Microphallidae (Family)
 Odhneria Sakai, 1983 accepted as Odhnea Ng & Low, 2010 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Xanthidae (Family)
 Odhneria Baer, 1924 accepted as Encyclometra Baylis & Cannon, 1924 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Plagiorchiida (Order) > Encyclometridae (Family)

Odina
     Odina Mabille, 1891 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Hesperiidae (Family)
 Odina Roxburgh, 1832 accepted as Lannea A. Richard in J.B.A. Guillemin et al., 1831 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Sapindales (Order) > Anacardiaceae (Family)

Odinia
     Odinia Robineau-Desvoidy, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Odiniidae (Family)
 Odinia Perrier, 1885 accepted as Novodinia Dartnall, Pawson, Pope & B.J. Smith, 1969 (Odinia preoccupied, new name designated. see Dartnall et al.) · Animalia (Kingdom) > Echinodermata (Phylum) > Asteroidea (Class) > Forcipulatida (Order) > Brisingidae (Family)

Odius
 Odius Thorell, 1876 accepted as Odiellus Roewer, 1923 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Opiliones (Order) > Phalangiidae (Family)
 Odius Stål, 1867 accepted as Caystrus Stål, 1861 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Pentatomidae (Family)
     Odius Liljeborg, 1865 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Amphipoda (Order) > Ochlesidae (Family)

Odobenus
     Odobenus Brisson, 1762 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Odobenidae (Family)
 Odobenus Rafinesque, 1815 accepted as Dugong Lacépède, 1799 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Sirenia (Order) > Dugongidae (Family)

Odonestis
     Odonestis Germar, 1811 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lasiocampidae (Family)
 Odonestis Stephens, 1828 accepted as Philudoria Kirby, 1892 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lasiocampidae (Family)

Odonia
     Odonia Bertoloni, 1822 accepted as Odonia Bertoloni, 1822 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)
 Odonia Bergroth, 1889 accepted as Eumenotes Westwood, 1846 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Eumenotidae (Family)

Odontaeus
     Odontaeus Dejean, 1821 accepted as Odonteus Samouelle, 1819 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Geotrupidae (Family)
 Odontaeus Say, 1823 accepted as Odonteus Samouelle, 1819 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Geotrupidae (Family)

Odontartemon
     Odontartemon Kobelt, 1905 accepted as Odontartemon Kobelt, 1905 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Odontartemon L. Pfeiffer, 1856 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Streptaxidae (Family)

Odontella
     Odontella C.Agardh, 1832 · Chromista (Kingdom) > Ochrophyta (Phylum) > Bacillariophyceae (Class) > Triceratiales (Order) > Triceratiaceae (Family)
     Odontella Schäffer, 1897 · Animalia (Kingdom) > Arthropoda (Phylum) > Collembola (Class) > Poduromorpha (Order) > Hypogastruridae (Family)
 Odontella Van Tieghem, 1895 accepted as Loranthella S. Blanco & C.E. Wetzel, 2016 (junior homonym) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Santalales (Order) > Loranthaceae (Family)

Odonteus
     Odonteus Samouelle, 1819 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Geotrupidae (Family)
 Odonteus Agassiz, 1835 † accepted as Odonteobolca Krell, 1991 † · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Perciformes (awaiting allocation) (Family)

Odontia
     Odontia Duponchel in Godart, 1832 accepted as Odontia Duponchel in Godart, 1832 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
 Odontia E.M. Fries, 1835 accepted as Steccherinum S.F. Gray, 1821 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Polyporales (Order) > Meruliaceae (Family)
 Odontia Persoon, 1794 accepted as Tomentella Johan-Olsen in Brefeld, 1888 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Thelephorales (Order) > Thelephoraceae (Family)
 Odontia S.F. Gray, 1821 accepted as Tomentella Johan-Olsen in Brefeld, 1888 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Thelephorales (Order) > Thelephoraceae (Family)

Odontidium
     Odontidium Kützing, 1844 · Chromista (Kingdom) > Ochrophyta (Phylum) > Bacillariophyceae (Class) > Bacillariophyceae (awaiting allocation) (Order) > Bacillariophyceae (awaiting allocation) (Family)
 Odontidium Philippi, 1836 accepted as Caecum Fleming, 1813 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Littorinimorpha (Order) > Caecidae (Family)

Odontina
     Odontina Guenée in Maillard, 1862 † accepted as Odontina Guenée in Maillard, 1862 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Odontina Zborzewski, 1834 accepted as Odontina Zborzewski, 1834 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Odontina Patouillard, 1887 accepted as Steccherinum S.F. Gray, 1821 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Polyporales (Order) > Meruliaceae (Family)

Odontionopa
     Odontionopa Chevrolat, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
 Odontionopa Erichson, 1842 accepted as Eboo Reid, 1993 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Odontionopa Dejean, 1835 accepted as Eboo Reid, 1993 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Odontionopa Motschulsky, 1866 accepted as Scelodonta Westwood, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Odontiopsis
     Odontiopsis J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
     Odontiopsis K. Hjortstam & L. Ryvarden, 1980 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Hymenochaetales (Order) > Schizoporaceae (Family)
 Odontiopsis J.M.H. Shaw, 2004 accepted as Odontiopsis J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Odontites
     Odontites Ludwig, 1757 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Orobanchaceae (Family)
 Odontites K.P.J. Sprengel, 1812 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Apiales (Order) > Apiaceae (Family)

Odontium
 Odontium Rafinesque, 1817 accepted as Tomentella Johan-Olsen in Brefeld, 1888 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Thelephorales (Order) > Thelephoraceae (Family)
 Odontium Leconte, 1847 accepted as Bembidion Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Odontobaris
     Odontobaris Champion, 1909 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Odontobaris Clark, Whitehead & Warner, 1977 accepted as Odontobarus Faust, 1888 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Odontobius
     Odontobius de Vauzème, 1834 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Monhysterida (Order) > Monhysteridae (Family)
     Odontobius Eberth, 1863 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Desmodorida (Order) > Desmodoridae (Family)

Odontocarus
 Odontocarus Agassiz, 1846 accepted as Odontocarus Agassiz, 1846 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
     Odontocarus Solier, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Odontocephalus
     Odontocephalus Conrad, 1840 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Phacopida (Order) > Dalmanitidae (Family)
     Odontocephalus · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Oribatida (Order) > Carabodidae (Family)
 Odontocephalus Vogdes, 1893 † accepted as Odontopleura Emmrich, 1839 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Lichida (Order) > Odontopleuridae (Family)

Odontocera
 Odontocera Macquart, 1835 accepted as Ceratomyza Schiner, 1862 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Agromyzidae (Family)
     Odontocera Audinet-Serville, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Odontocera Chen & Yuan, 1996 accepted as Odontocera Chen & Yuan, 1996 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Odontocerus
     Odontocerus Guérin-Ménéville in Duperry, 1838 accepted as Odontocerus Guérin-Ménéville in Duperry, 1838 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Lycidae (Family)
 Odontocerus Stephens, 1829 accepted as Odontocerum Leach, 1815 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Trichoptera (Order) > Odontoceridae (Family)
 Odontocerus Schenkling, 1927 accepted as Odontoderus Schwarz, 1894 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Elateridae (Family)
     Odontocerus Leach, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Decapoda incertae sedis (Family)

Odontochile
     Odontochile Hawle & Corda, 1847 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Phacopida (Order) > Diaphanometopidae (Family)
 Odontochile Tilesius, 1850 accepted as Odontocheila Laporte, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Odontochilus
     Odontochilus Richmond, 1915 accepted as Odontochilus Richmond, 1915 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Odontochilus Blume, 1858 (?) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Odontocryptus
     Odontocryptus Szépligeti, 1916 accepted as Odontocryptus Szépligeti, 1916 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
     Odontocryptus Saussure, ? 1890 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Ichneumonidae (Family)
     Odontocryptus Uchida, 1932 accepted as Odontocryptus Uchida, 1932 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
     Odontocryptus Seyrig, 1952 accepted as Odontocryptus Seyrig, 1952 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Ichneumonidae (Family)
 Odontocryptus Cameron, 1903 accepted as Neodontocryptus Uchida, 1940 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Ichneumonidae (Family)

Odontocyathus
 Odontocyathus Moseley, 1881 accepted as Stephanocyathus Seguenza, 1864 · Animalia (Kingdom) > Cnidaria (Phylum) > Anthozoa (Class) > Scleractinia (Order) > Caryophylliidae (Family)
 Odontocyathus Brook, 1893 accepted as Acropora Oken, 1815 · Animalia (Kingdom) > Cnidaria (Phylum) > Anthozoa (Class) > Scleractinia (Order) > Acroporidae (Family)

Odontodamaeus
     Odontodamaeus Paschoal, 1982 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Oribatida (Order) > Gymnodamaeidae (Family)
     Odontodamaeus Paschoal in Paschoal & Johnston, 1982 accepted as Odontodamaeus Paschoal in Paschoal & Johnston, 1982 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Acari (awaiting allocation) (Order) > Acari (awaiting allocation) (Family)

Odontoderes
     Odontoderes Haupt, 1929 accepted as Odontoderes Haupt, 1929 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Pompilidae (Family)
     Odontoderes Dejean, 1835 accepted as Odontoderes Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Odontoderes Schönherr in Sahlberg, 1823 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Odontoderes Saunders, 1846 accepted as Cadmus Erichson, 1842 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Odontoderus
     Odontoderus Schwarz, 1894 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Elateridae (Family)
 Odontoderus Clouët, 1900 accepted as Odontolochus Schmidt, 1917 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Odontognathus
     Odontognathus Lacepède, 1800 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Clupeiformes (Order) > Pristigasteridae (Family)
 Odontognathus Laporte, 1840 accepted as Pelidnota Macleay, 1819 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Odontolabis
     Odontolabis Hope, 1842 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Lucanidae (Family)
 Odontolabis Hope & Westwood, 1845 accepted as Odontolabis Hope, 1842 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Lucanidae (Family)

Odontoloma
     Odontoloma Boheman, 1857 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Odontoloma Kunth in Humboldt, Bonpland & Kunth, 1818 accepted as Odontoloma Kunth in Humboldt, Bonpland & Kunth, 1818 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
 Odontoloma J. Smith, 1841 accepted as Lindsaea Dryander ex Smith, 1793 · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Polypodiales (Order) > Lindsaeaceae (Family)

Odontolophus
     Odontolophus Cassini in F. Cuvier, 1827 accepted as Odontolophus Cassini in F. Cuvier, 1827 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
     Odontolophus Bate, 1888 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Decapoda incertae sedis (Family)

Odontomachus
     Odontomachus Latreille, 1804 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Formicidae (Family)
 Odontomachus Schönherr, 1845 accepted as Odontomaches Schönherr, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Odontomastax
     Odontomastax Bolivar y Pieltain, 1944 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Chorotypidae (Family)
 Odontomastax Descamps, 1965 accepted as Rhabdomastax Descamps, 1969 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Episactidae (Family)

Odontomerus
     Odontomerus Leach in Bowdich, 1819 accepted as Odontomerus Leach in Bowdich, 1819 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Buprestidae (Family)
     Odontomerus Chevrolat in Sturm, 1843 accepted as Odontomerus Chevrolat in Sturm, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Odontomerus Gistl, 1834 accepted as Odontomerus Gistl, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
 Odontomerus Gravenhorst, 1829 accepted as Odontocolon Cushman, 1942 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Ichneumonidae (Family)
 Odontomerus Solier in Gay, 1849 accepted as Baripus Dejean, 1828 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Odontomorpha
     Odontomorpha M. Hajós, 1966 † · Protozoa (Kingdom) > Acritarcha (Phylum) > Acritarcha (awaiting allocation) (Class) > Acritarcha (awaiting allocation) (Order) > Acritarcha (awaiting allocation) (Family)
 Odontomorpha Selman, 1965 accepted as Odontiomorpha Jacoby, 1900 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Odontomus
     Odontomus Duméril, 1853 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Colubridae (Family)
 Odontomus Kirby in Richardson, 1837 accepted as Chrysobothris Eschscholtz, 1829 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Buprestidae (Family)

Odontonema
     Odontonema C.G.D. Nees, 1842 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Acanthaceae (Family)
 Odontonema Nees ex Endlicher, 1842 accepted as Odontonema Nees ex Endlicher, 1842 (nomen rejiciendum) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Acanthaceae (Family)
 Odontonema Weber, 1913 accepted as Kali Lloyd, 1909 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Chiasmodontidae (Family)
 Odontonema Filipjev, 1929 accepted as Chromadorita Filipjev, 1918 (synonym) · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Chromadorida (Order) > Chromadoridae (Family)

Odontonia
     Odontonia Fransen, 2002 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Palaemonidae (Family)
     Odontonia Rolfe, 1905 accepted as Odontonia Rolfe, 1905 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Odontonyx
 Odontonyx Guérin-Ménéville, 1843 accepted as Paralichas White, 1859 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Odontonyx Stephens, 1827 accepted as Olisthopus Dejean, 1828 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Odontonyx Rübsaamen, 1894 accepted as Phorodonta Coquillett, 1910 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Sciaridae (Family)

Odontopareius
     Odontopareius Damoiseau, 1964 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Brentidae (Family)
 Odontopareius Damoiseau, 1963 accepted as Odontopareius Damoiseau, 1964 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Brentidae (Family)

Odontophora
     Odontophora Bütschli, 1874 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Monhysterida (Order) > Axonolaimidae (Family)
     Odontophora Allgén, 1930 accepted as Odontophora Allgén, 1930 (unassessed) · Animalia (Kingdom) > Nematoda (Phylum) > Nematoda (awaiting allocation) (Class) > Nematoda (awaiting allocation) (Order) > Nematoda (awaiting allocation) (Family)

Odontophorus
     Odontophorus Vieillot, 1816 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Galliformes (Order) > Odontophoridae (Family)
     Odontophorus N.E. Brown, 1927 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Caryophyllales (Order) > Aizoaceae (Family)

Odontophyllum
     Odontophyllum Simpson, 1900 † · Animalia (Kingdom) > Cnidaria (Phylum) > Anthozoa (Class) > Rugosa (Order) > Halliidae (Family)
     Odontophyllum (Lessing) Spach, 1841 accepted as Odontophyllum (Lessing) Spach, 1841 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
 Odontophyllum C.P. Sreemadhavan, 1977 accepted as Aphelandra R. Brown, 1810 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Acanthaceae (Family)

Odontopsis
     Odontopsis Förster, 1868 accepted as Odontopsis Förster, 1868 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
 Odontopsis van Hasselt, 1823 accepted as Aplocheilus McClelland, 1839 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cyprinodontiformes (Order) > Aplocheilidae (Family)

Odontoptera
 Odontoptera Agassiz, 1846 accepted as Odontoptera Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Odontoptera Carreño, 1842 accepted as Odontoptera Carreño, 1842 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Odontoptera Cassini in F. Cuvier, 1825 accepted as Odontoptera Cassini in F. Cuvier, 1825 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)

Odontopteris
 Odontopteris Bernhardi, 1801 accepted as Lygodium O. Swartz, 1801 · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Schizaeales (Order) > Lygodiaceae (Family)
     Odontopteris (A.T. Brongniart) Sternberg, 1825 † · Plantae (Kingdom) > Tracheophyta (Phylum) > Pteridospermopsida (Class) > Pachytestales (Order) > Pachytestaceae (Family)

Odontopus
     Odontopus Laporte, 1832 accepted as Odontopus Laporte, 1832 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Odontopus Say, 1831 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Odontopus Silbermann, 1833 accepted as Odontopezus Alluaud, 1889 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Odontopyge
     Odontopyge Brandt, 1841 accepted as Odontopyge Brandt, 1841 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Diplopoda (Class) > Spirostreptida (Order) > Spirostreptidae (Family)
     Odontopyge Hawle & Corda, 1847 † accepted as Odontopyge Hawle & Corda, 1847 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Trilobita (awaiting allocation) (Order) > Trilobita (awaiting allocation) (Family)

Odontorhynchus
     Odontorhynchus Karling, 1947 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Turbellaria (Class) > Neorhabdocoela (Order) > Gnathorhynchidae (Family)
     Odontorhynchus Stolley, 1936 † · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Pterosauria (Order) > Rhamphorhynchidae (Family)
 Odontorhynchus Pelzeln, 1868 accepted as Odontorchilus Richmond, 1915 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Certhiidae (Family)
 Odontorhynchus Chevrolat, 1880 accepted as Metamasius Horn, 1873 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Dryophthoridae (Family)

Odontoscelis
     Odontoscelis Laporte, 1832 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Scutelleridae (Family)
 Odontoscelis Curtis, 1838 accepted as Cnemalobus Guérin, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Odontosema
     Odontosema Kieffer, 1909 accepted as Odontosema Kieffer, 1909 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
 Odontosema Warren in Seitz, 1913 accepted as Tesomonoda Nye, 1975 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)

Odontosoma
     Odontosoma Townsend, 1916 accepted as Odontosoma Townsend, 1916 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Diptera (awaiting allocation) (Family)
 Odontosoma Silhavý, 1946 accepted as Metaphalangium Roewer, 1911 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Opiliones (Order) > Phalangiidae (Family)
 Odontosoma Breuning, 1950 accepted as Spinosomatidia Hunt & Breuning, 1955 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Odontostele
     Odontostele J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Odontostele J.M.H. Shaw, 2004 accepted as Odontostele J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Odontostoma
     Odontostoma Seyrig, 1952 accepted as Odontostoma Seyrig, 1952 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Ichneumonidae (Family)
     Odontostoma d'Orbigny in Sagra, 1842 accepted as Odontostoma d'Orbigny in Sagra, 1842 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Odontostoma Agassiz, 1846 accepted as Odontostoma Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Odontostoma Philippi, 1853 accepted as Odostomia Fleming, 1813 (Invalid: unjustified emendation of Odostomia) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)
 Odontostoma accepted as Odontostomus Cocco, 1838 (misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Aulopiformes (Order) > Evermannellidae (Family)
 Odontostoma Mörch, 1852 accepted as Linnerita Vermeij, 1984 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Cycloneritimorpha (Order) > Neritidae (Family)
 Odontostoma Turton in Carrington, 1830 accepted as Odostomia Fleming, 1813 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)

Odontostomia
 Odontostomia Jeffreys, 1839 accepted as Odostomia Fleming, 1813 (Invalid: unjustified emendation of Odostomia) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)
 Odontostomia G.B. Sowerby I, 1839 accepted as Odostomia Fleming, 1813 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)
 Odontostomia Philippi, 1849 accepted as Odostomia Fleming, 1813 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)

Odontostomus
     Odontostomus Beck, 1837 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Orthalicidae (Family)
 Odontostomus Cocco, 1838 accepted as Evermannella Fowler, 1901 (synonym) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Aulopiformes (Order) > Evermannellidae (Family)

Odontostylis
     Odontostylis Blume, 1828 accepted as Odontostylis Blume, 1828 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Odontostylis Breda, 1828 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Odontostylus
     Odontostylus Trouessart, 1898 † accepted as Odontostylus Trouessart, 1898 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
     Odontostylus Gray, 1840 accepted as Odontostylus Gray, 1840 · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Odontota
     Odontota Mannerheim, 1843 accepted as Odontota Mannerheim, 1843 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Odontota Dejean, 1835 accepted as Odontota Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Odontota Chevrolat, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Odontotabanus
     Odontotabanus Borgmeier, 1933 accepted as Odontotabanus Borgmeier, 1933 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Diptera (awaiting allocation) (Family)
     Odontotabanus Lutz, 1918 accepted as Odontotabanus Lutz, 1918 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Diptera (awaiting allocation) (Family)

Odontotrema
     Odontotrema Nylander, 1858 · Fungi (Kingdom) > Ascomycota (Phylum) > Lecanoromycetes (Class) > Ostropales (Order) > Odontotremataceae (Family)
     Odontotrema Lindholm, 1927 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Hygromiidae (Family)
 Odontotrema Hafeezullah & Siddiqi, 1970 accepted as Odontocotyle Hafeezullah & Siddiqi, 1971 (pre-occupied) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Plagiorchiida (Order) > Faustulidae (Family)

Odontotrochus
     Odontotrochus Moseley, 1881 accepted as Odontotrochus Moseley, 1881 (unassessed) · Animalia (Kingdom) > Cnidaria (Phylum) > Cnidaria (awaiting allocation) (Class) > Cnidaria (awaiting allocation) (Order) > Cnidaria (awaiting allocation) (Family)
     Odontotrochus P. Fischer, 1880 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Vetigastropoda (Order) > Trochidae (Family)

Odontotropis
     Odontotropis Grunow, 1884 † · Chromista (Kingdom) > Ochrophyta (Phylum) > Bacillariophyceae (Class) > Bacillariophyceae (awaiting allocation) (Order) > Bacillariophyceae (awaiting allocation) (Family)
     Odontotropis Humbert & Saussure, 1869 accepted as Odontotropis Humbert & Saussure, 1869 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Diplopoda (Class) > Polydesmida (Order) > Chelodesmidae (Family)
 Odontotropis Agassiz, 1846 accepted as Odontotropis Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Odontura
     Odontura F.E. Clements, 1909 · Fungi (Kingdom) > Ascomycota (Phylum) > Lecanoromycetes (Class) > Ostropales (Order) > Odontotremataceae (Family)
     Odontura Rambur, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Phaneropteridae (Family)
     Odontura Fischer & Crosse, 1872 accepted as Odontura Fischer & Crosse, 1872 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Odopoea
     Odopoea Stål, 1862 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Cicadidae (Family)
 Odopoea Dalla Torre, 1898 accepted as Odopoia Walker, 1871 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Torymidae (Family)

Odostomia
     Odostomia Fleming, 1813 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)
     Odostomia Say in Nicholson, 1816 accepted as Odostomia Say in Nicholson, 1816 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Odostomia Fleming, 1822 accepted as Odostomia Fleming, 1813 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)
 Odostomia Fleming, 1828 accepted as Odostomia Fleming, 1813 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)

Oebalus
     Oebalus Rafinesque, 1815 accepted as Oebalus Rafinesque, 1815 · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Oebalus Stål, 1862 accepted as Solubea Bergroth, 1891 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Pentatomidae (Family)

Oeceoptoma
 Oeceoptoma Leach, 1815 accepted as Oiceoptoma Leach, 1815 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Silphidae (Family)
 Oeceoptoma Agassiz, 1846 accepted as Oiceoptoma Leach, 1815 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Silphidae (Family)

Oecothea
     Oecothea Curtis, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Heleomyzidae (Family)
 Oecothea auct accepted as Neoecothea Peterson, 1982 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Heleomyzidae (Family)

Oedalia
 Oedalia Carpenter, 1864 accepted as Cooperella Carpenter, 1864 (synonym) · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Veneridae (Family)
 Oedalia Meigen, 1838 accepted as Oedalea Meigen, 1820 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Hybotidae (Family)

Oedecnema
     Oedecnema Thomson, 1857 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Oedecnema Dejean, 1835 accepted as Oedecnema Thomson, 1857 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Oedematopus
     Oedematopus Van Duzee, 1929 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Dolichopodidae (Family)
 Oedematopus Planchon & Triana, 1860 accepted as Clusia Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malpighiales (Order) > Clusiaceae (Family)

Oedera
 Oedera Crantz, 1768 accepted as Oedera Crantz, 1768 (nomen rejiciendum) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Liliales (Order) > Liliaceae (Family)
     Oedera Linnaeus, 1771 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)

Oedicephalus
     Oedicephalus Cresson, 1868 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Ichneumonidae (Family)
 Oedicephalus Nevski, 1937 accepted as Astragalus Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)

Oedicerus
 Oedicerus Redtenbacher in Huegel, 1844 accepted as Taumacera Thunberg, 1814 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
 Oedicerus Dana, 1849 accepted as Oediceros Krøyer, 1842 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Amphipoda (Order) > Oedicerotidae (Family)

Oediprosopus
     Oediprosopus Marshall, 1958 accepted as Oediprosopus Marshall, 1958 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Oediprosopus Wollaston, 1873 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Oedipus
     Oedipus Berthold in Latreille, 1827 accepted as Oedipus Berthold in Latreille, 1827 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Acrididae (Family)
     Oedipus Tschudi, 1838 accepted as Oedipus Tschudi, 1838 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Caudata (Order) > Plethodontidae (Family)
     Oedipus Menge, 1876 accepted as Oedipus Menge, 1876 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Arachnida (awaiting allocation) (Order) > Arachnida (awaiting allocation) (Family)
 Oedipus Lesson, 1840 accepted as Saguinus Hoffmannsegg, 1807 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Primates (Order) > Cebidae (Family)
 Oedipus Bataille, 1908 accepted as Boletus E.M. Fries, 1821 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Boletales (Order) > Boletaceae (Family)
 Oedipus Dana, 1852 accepted as Coralliocaris Stimpson, 1860 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Palaemonidae (Family)

Oehlertella
     Oehlertella Hall & Clarke, 1892 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Lingulata (Class) > Linguliporida (Order) > Discinidae (Family)
     Oehlertella Hall & Clarke, 1889 † accepted as Oehlertella Hall & Clarke, 1892 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Lingulata (Class) > Linguliporida (Order) > Discinidae (Family)

Oehlertia
     Oehlertia Perner in Barrande, 1907 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Archaeogastropoda (Order) > Archaeogastropoda (awaiting allocation) (Family)
     Oehlertia Pillet, 1972 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Proetida (Order) > Proetida (awaiting allocation) (Family)

Oekentorpia
     Oekentorpia May, 1993 † accepted as Oekentorpia May, 1993 † (unassessed) · Animalia (Kingdom) > Cnidaria (Phylum) > Anthozoa (Class) > Anthozoa (awaiting allocation) (Order) > Anthozoa (awaiting allocation) (Family)
     Oekentorpia Langer, 1997 † accepted as Oekentorpia Langer, 1997 † (unassessed) · Animalia (Kingdom) > Problematica (Phylum) > Problematica (awaiting allocation) (Class) > Problematica (awaiting allocation) (Order) > Problematica (awaiting allocation) (Family)

Oeme
     Oeme Newman, 1840 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Oeme Philippi, 1844 accepted as Oeme Philippi, 1844 (unassessed) · Animalia (Kingdom) > Cnidaria (Phylum) > Cnidaria (awaiting allocation) (Class) > Cnidaria (awaiting allocation) (Order) > Cnidaria (awaiting allocation) (Family)

Oenanthe
     Oenanthe Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Apiales (Order) > Apiaceae (Family)
     Oenanthe Vieillot, 1816 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Muscicapidae (Family)
     Oenanthe Pallas, 1771 accepted as Oenanthe Vieillot, 1816 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Muscicapidae (Family)

Oenas
     Oenas Vieillot, 1816 accepted as Oenas Vieillot, 1816 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Columbiformes (Order) > Columbidae (Family)
     Oenas Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Meloidae (Family)

Oeneis
     Oeneis Hübner, 1819 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Satyridae (Family)
 Oeneis Mulsant, 1850 accepted as Calloeneis Grote, 1873 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coccinellidae (Family)

Oenochroma
     Oenochroma Guenée, 1857 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
 Oenochroma Pascoe, 1872 accepted as Oenopus Marshall, 1943 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Oenone
     Oenone Hartman, 1881 accepted as Oenone Hartman, 1881 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Oenone Lamarck, 1818 · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Aciculata (Order) > Oenonidae (Family)
 Oenone Agassiz, 1846 accepted as Oenone Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Aciculata (Order) > Oenonidae (Family)
 Oenone Haliday, 1839 accepted as Oenone Haliday, 1839 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
 Oenone Meyrick, 1890 accepted as Dirce Prout, 1910 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
 Oenone Tulasne, 1849 accepted as Apinagia L.R. Tulasne, 1849 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malpighiales (Order) > Podostemaceae (Family)

Oenopia
     Oenopia Stål, 1867 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Lophopidae (Family)
     Oenopia Mulsant, 1850 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coccinellidae (Family)
 Oenopia Melichar, 1914 accepted as Meloenopia Metcalf, 1952 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Lophopidae (Family)

Oerope
 Oerope Bourguignat, 1889 accepted as Natalina Pilsbry in Tryon & Pilsbry, 1893 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Rhytididae (Family)
 Oerope Pomel, 1883 accepted as Aerope Jeffreys, 1876 · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Spatangoida (Order) > Aeropsidae (Family)

Oestlundia
     Oestlundia Hille Ris Lambers, 1949 † accepted as Oestlundia Hille Ris Lambers, 1949 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Aphididae (Family)
     Oestlundia W.E. Higgins, 2001 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Oestropsis
     Oestropsis Townsend, 1912 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Tachinidae (Family)
     Oestropsis Brauer, 1868 accepted as Oestropsis Brauer, 1868 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Trichoptera (Order) > Trichoptera (awaiting allocation) (Family)
 Oestropsis Smith, 1868 accepted as Stenotritus Smith, 1853 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Stenotritidae (Family)

Oeta
     Oeta Grote, 1865 accepted as Oeta Grote, 1865 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Yponomeutidae (Family)
 Oeta Cambridge, 1871 accepted as Schenkeliella Strand, 1934 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Tetragnathidae (Family)
 Oeta Simon, 1894 accepted as Schenkeliella Strand, 1934 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Tetragnathidae (Family)

Oetosis
 Oetosis Necker ex E.L. Greene, 1900 accepted as Vittaria Smith, 1793 · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Polypodiales (Order) > Pteridaceae (Family)
 Oetosis Necker ex O. Kuntze, 1891 accepted as Pyrrosia Mirbel in Lamarck & Mirbel, 1802 · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Polypodiales (Order) > Polypodiaceae (Family)

Ogcocephalus
     Ogcocephalus Gemminger & Harold, 1869 accepted as Ogcocephalus Gemminger & Harold, 1869 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Ogcocephalus Fischer, 1813 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Lophiiformes (Order) > Ogcocephalidae (Family)

Ogdenia
     Ogdenia Simon, 1894 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Salticidae (Family)
     Ogdenia Peckham & Peckham, 1908 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Salticidae (Family)
 Ogdenia Peckham, 1908 accepted as Ogdenia Peckham & Peckham, 1908 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Salticidae (Family)

Ogilviella
     Ogilviella Lenz, 1968 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Rhynchonellata (Class) > Atrypida (Order) > Atrypinidae (Family)
     Ogilviella Paramonov, 1954 accepted as Ogilviella Paramonov, 1954 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Bombyliidae (Family)
 Ogilviella Eliasova, 1973 † accepted as Ogilvinella Eliasova, 1976 † · Animalia (Kingdom) > Cnidaria (Phylum) > Anthozoa (Class) > Scleractinia (Order) > Rhipidogyridae (Family)

Ogloblinia
     Ogloblinia Canals, 1933 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Opiliones (Order) > Gonyleptidae (Family)
     Ogloblinia Csiki, 1939 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Ognevia
     Ognevia Ikonnikov, 1911 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Acrididae (Family)
 Ognevia Heptner & Dolgov, 1967 accepted as Sorex Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Insectivora (Order) > Soricidae (Family)

Ogoria
 Ogoria Fischer de Waldheim, 1814 accepted as Ogoria Fischer de Waldheim, 1814 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
 Ogoria Grünberg, 1911 accepted as Ogovia Holland, 1892 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)

Ogovia
     Ogovia Holland, 1892 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
 Ogovia Hansen & Sørensen, 1904 accepted as Ogovea Roewer, 1923 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Opiliones (Order) > Ogoveidae (Family)

Ogyges
     Ogyges Kaup, 1871 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Passalidae (Family)
     Ogyges Rafinesque, 1815 accepted as Ogyges Rafinesque, 1815 · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Polychaeta (awaiting allocation) (Order) > Polychaeta (awaiting allocation) (Family)

Ogygia
 Ogygia Hübner, 1821 accepted as Yigoga Nye, 1975 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
 Ogygia Brongniart in Desmarest, 1817 † accepted as Ogygiocaris Angelin, 1852 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Asaphida (Order) > Asaphidae (Family)

Ogyris
     Ogyris Westwood in Doubleday & Westwood, 1851 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lycaenidae (Family)
 Ogyris Stimpson, 1860 accepted as Ogyrides Stebbing, 1914 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Ogyrididae (Family)

Ohigginsia
     Ohigginsia Neunzig & Goodson, 1992 accepted as Ohigginsia Neunzig & Goodson, 1992 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Pyralidae (Family)
 Ohigginsia Ruiz & Pavon, 1798 accepted as Hoffmannia O. Swartz, 1788 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Rubiaceae (Family)

Ohridia
     Ohridia Nezlobinski, 1926 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Desmodorida (Order) > Microlaimidae (Family)
     Ohridia Schneider in Stankovic, 1932 accepted as Ohridia Schneider in Stankovic, 1932 (unassessed) · Animalia (Kingdom) > Nematoda (Phylum) > Nematoda (awaiting allocation) (Class) > Nematoda (awaiting allocation) (Order) > Nematoda (awaiting allocation) (Family)
 Ohridia Schneider, 1943 accepted as Domorganus Goodey, 1946 (homonym) · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Leptolaimida (Order) > Ohridiidae (Family)

Oiacurus
 Oiacurus Leuckart, 1821 accepted as Triturus Rafinesque, 1815 · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Caudata (Order) > Salamandridae (Family)
 Oiacurus Fitzinger, 1843 accepted as Uroplatus Duméril, 1806 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Gekkonidae (Family)

Oicomonas
 Oicomonas Scherffel, 1901 accepted as · Chromista (Kingdom) > Ochrophyta (Phylum) > Chrysophyceae (Class) > Chromulinales (Order) > Chromulinales incertae sedis (Family)
 Oicomonas W.S. Kent, 1880 accepted as Oikomonas Kent, 1880 · Chromista (Kingdom) > Ochrophyta (Phylum) > Chrysophyceae (Class) > Chromulinales (Order) > Chromulinaceae (Family)
 Oicomonas Doflein, 1928 accepted as Oikomonas Kent, 1880 · Chromista (Kingdom) > Ochrophyta (Phylum) > Chrysophyceae (Class) > Chromulinales (Order) > Chromulinaceae (Family)

Oidium
     Oidium Link in Willdenow, 1824 · Fungi (Kingdom) > Ascomycota (Phylum) > Leotiomycetes (Class) > Erysiphales (Order) > Erysiphaceae (Family)
 Oidium P.A. Saccardo, 1880 accepted as Oidium Link in Willdenow, 1824 · Fungi (Kingdom) > Ascomycota (Phylum) > Leotiomycetes (Class) > Erysiphales (Order) > Erysiphaceae (Family)
 Oidium Link, 1809 accepted as Oidium Link in Willdenow, 1824 · Fungi (Kingdom) > Ascomycota (Phylum) > Leotiomycetes (Class) > Erysiphales (Order) > Erysiphaceae (Family)

Oinia
     Oinia Eskov, 1984 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Linyphiidae (Family)
 Oinia Hedqvist, 1978 accepted as Acrias Walker, 1847 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Eulophidae (Family)

Oithona
     Oithona Baird, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Maxillopoda (Class) > Cyclopoida (Order) > Oithonidae (Family)
 Oithona Alder & Hancock, 1851 accepted as Fiona Alder & Hancock in Forbes & Hanley, 1851 (Invalid: junior homonym of Oithona Baird, 1843; Fiona is a replacement name) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Nudibranchia (Order) > Fionidae (Family)

Oithonella
     Oithonella Mörch in Rink, 1857 accepted as Oithonella Mörch in Rink, 1857 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Littorinimorpha (Order) > Velutinidae (Family)
 Oithonella Sars G.O., 1886 accepted as Oithona Baird, 1843 (synonym) · Animalia (Kingdom) > Arthropoda (Phylum) > Maxillopoda (Class) > Cyclopoida (Order) > Oithonidae (Family)
 Oithonella Mörch, 1857 accepted as Marsenina Gray, 1850 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Littorinimorpha (Order) > Velutinidae (Family)

Okadaia
 Okadaia Baba, 1930 accepted as Vayssierea Risbec, 1928 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Nudibranchia (Order) > Okadaiidae (Family)
 Okadaia de Laubenfels, 1936 accepted as Monanchora Carter, 1883 (junior synonym) · Animalia (Kingdom) > Porifera (Phylum) > Demospongea (Class) > Poecilosclerida (Order) > Crambeidae (Family)

Okamurina
 Okamurina A.D. Zinova, 1976 accepted as · Plantae (Kingdom) > Rhodophyta (Phylum) > Florideophyceae (Class) > Ceramiales (Order) > Delesseriaceae (Family)
     Okamurina A.D. Zinova, 1972 · Plantae (Kingdom) > Rhodophyta (Phylum) > Florideophyceae (Class) > Ceramiales (Order) > Delesseriaceae (Family)

Okenia
     Okenia Menke, 1830 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Nudibranchia (Order) > Goniodorididae (Family)
     Okenia Leuckart in Bronn, 1826 accepted as Okenia Leuckart in Bronn, 1826 · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Okenia Schlechtendal & Chamisso, 1830 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Caryophyllales (Order) > Nyctaginaceae (Family)
 Okenia Zetterstedt, 1838 accepted as Okeniella Hendel, 1907 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Scathophagidae (Family)

Olafsenia
     Olafsenia V.B.A. Trevisan, 1849 · Plantae (Kingdom) > Chlorophyta (Phylum) > Ulvophyceae (Class) > Bryopsidales (Order) > Udoteaceae (Family)
     Olafsenia Oudemans, 1924 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Astigmata (Order) > Acaridae (Family)

Olbia
     Olbia Marcusen, 1867 † · Animalia (Kingdom) > Arthropoda (Phylum) > Ostracoda (Class) > Podocopida (Order) > Podocopida (awaiting allocation) (Family)
     Olbia Pranskevichius, 1972 † accepted as Olbia Pranskevichius, 1972 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Ostracoda (Class) > Ostracoda (awaiting allocation) (Order) > Ostracoda (awaiting allocation) (Family)
     Olbia Stål, 1862 accepted as Olbia Stål, 1862 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Olbia Medikus, 1787 accepted as Olbia Medikus, 1787 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malvales (Order) > Malvaceae (Family)

Oldhamia
 Oldhamia Zittel, 1910 † accepted as Oldhamina Waagen, 1883 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Strophomenata (Class) > Strophomenatida (Order) > Oldhaminidae (Family)
     Oldhamia E. Forbes, 1848 † · Animalia (Kingdom) > Trace fossils (awaiting allocation) (Phylum) > (Class) > (Order) > (Family)

Oldroydia
     Oldroydia Hull, 1956 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Asilidae (Family)
     Oldroydia Dall, 1894 · Animalia (Kingdom) > Mollusca (Phylum) > Polyplacophora (Class) > Lepidopleurida (Order) > Leptochitonidae (Family)

Olea
     Olea Agersborg, 1923 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Sacoglossa (Order) > Limapontiidae (Family)
     Olea Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Oleaceae (Family)

Olearia
     Olearia Herrmannsen, 1847 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Vetigastropoda (Order) > Turbinidae (Family)
     Olearia Moench, 1802 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)

Olegaspis
     Olegaspis Ivshin, 1962 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Ptychopariida (Order) > Ptychopariida (awaiting allocation) (Family)
     Olegaspis Ivshin, 1983 † accepted as Olegaspis Ivshin, 1983 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Trilobita (awaiting allocation) (Order) > Trilobita (awaiting allocation) (Family)

Olemehlia
     Olemehlia Holzschuh, 2011 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Olemehlia Batelka, 2011 † accepted as Olemehliella Batelka, 2017 † (junior homonym) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Ripiphoridae (Family)

Olena
     Olena Laporte in Brullé, 1840 accepted as Olena Laporte in Brullé, 1840 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
 Olena Blanchard, 1851 accepted as Trycherus Gerstaecker, 1857 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Endomychidae (Family)

Olenekina
     Olenekina Ushatinskaya, 1997 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Paterinata (Class) > Paterinida (Order) > Paterinidae (Family)
     Olenekina Egorova, 1970 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Ptychopariida (Order) > Ptychopariida (awaiting allocation) (Family)

Olenopsis
     Olenopsis Ameghino, 1889 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Dinomyidae (Family)
 Olenopsis Bornemann, 1891 † accepted as Dolerolenus Leanza, 1949 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Redlichiida (Order) > Dolerolenidae (Family)

Olenus
     Olenus Dejean, 1835 accepted as Olenus Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Endomychidae (Family)
     Olenus Dalman, 1826 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Ptychopariida (Order) > Ptychopariidae (Family)
 Olenus Thomson, 1857 accepted as Trycherus Gerstaecker, 1857 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Endomychidae (Family)

Olfa
     Olfa Adanson, 1763 accepted as Olfa Adanson, 1763 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Ranunculales (Order) > Ranunculaceae (Family)
 Olfa Cossmann, 1907 † accepted as Ulfa Dall & Bartsch, 1904 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)

Olfersia
     Olfersia Leach, 1817 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Hippoboscidae (Family)
     Olfersia Raddi, 1819 · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Polypodiales (Order) > Dryopteridaceae (Family)
 Olfersia Wiedemann, 1830 accepted as Olfersia Leach, 1817 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Hippoboscidae (Family)

Olgia
     Olgia Radoszkowski, 1877 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Crabronidae (Family)
 Olgia Mikhalevich, 2011 accepted as Olgita Mikhalevich, 2017 (junior homonym) · Chromista (Kingdom) > Retaria (Phylum) > Globothalamea (Class) > Textulariida (Order) > Olgiidae (Family)

Oligactis
     Oligactis (Kunth) Cassini in F. Cuvier, 1825 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
 Oligactis Rafinesque, 1837 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)

Oligandra
 Oligandra Lessing, 1834-1835 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Caryophyllales (Order) > Amaranthaceae (Family)
 Oligandra Lessing, 1832 accepted as Lucilia Cassini, 1817 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)

Oligella
     Oligella Rossau et al., 1987 · Bacteria (Kingdom) > Proteobacteria (Phylum) > Betaproteobacteria (Class) > Burkholderiales (Order) > Alcaligenaceae (Family)
     Oligella Motschoulsky, 1869 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Ptiliidae (Family)

Oligobiotherium
     Oligobiotherium Ameghino, 1901 † accepted as Oligobiotherium Ameghino, 1901 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
     Oligobiotherium Ameghino, 1902 † accepted as Oligobiotherium Ameghino, 1902 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)

Oligocanthopus
 Oligocanthopus Beier, 1935 accepted as Xanthomantis Giglio-Tos, 1915 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Mantodea (Order) > Iridopterygidae (Family)
     Oligocanthopus Rehn & Hebard, 1912 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Mogoplistidae (Family)

Oligoceras
     Oligoceras Zhuravleva, 1974 † · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Oncocerida (Order) > Oncocerida (awaiting allocation) (Family)
     Oligoceras Gagnepain, 1925 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malpighiales (Order) > Euphorbiaceae (Family)
 Oligoceras Schulze, 1880 accepted as Hyrtios Duchassaing & Michelotti, 1864 (junior synonym) · Animalia (Kingdom) > Porifera (Phylum) > Demospongea (Class) > Dictyoceratida (Order) > Thorectidae (Family)

Oligoclada
     Oligoclada Karsch, 1890 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Odonata (Order) > Libellulidae (Family)
     Oligoclada Pearse, 1938 accepted as Oligoclada Pearse, 1938 (unassessed) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Turbellaria (Class) > Turbellaria (awaiting allocation) (Order) > Turbellaria (awaiting allocation) (Family)

Oligocladus
     Oligocladus Lang, 1884 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Turbellaria (Class) > Polycladida (Order) > Euryleptidae (Family)
     Oligocladus Chodat & Wilczek, 1902 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Apiales (Order) > Apiaceae (Family)
 Oligocladus Weber-van Bosse, 1911 accepted as Oligocladella P.C. Silva, 1996 (synonym) · Plantae (Kingdom) > Rhodophyta (Phylum) > Florideophyceae (Class) > Ceramiales (Order) > Rhodomelaceae (Family)

Oligocletodes
 Oligocletodes Lang, 1944 accepted as Eurycletodes Sars G.O., 1909 · Animalia (Kingdom) > Arthropoda (Phylum) > Maxillopoda (Class) > Harpacticoida (Order) > Argestidae (Family)
 Oligocletodes Lang, 1948 accepted as Eurycletodes Sars G.O., 1909 · Animalia (Kingdom) > Arthropoda (Phylum) > Maxillopoda (Class) > Harpacticoida (Order) > Argestidae (Family)

Oligodon
     Oligodon Amalitzky, 1892 † accepted as Oligodon Amalitzky, 1892 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Bivalvia (awaiting allocation) (Order) > Bivalvia (awaiting allocation) (Family)
     Oligodon Boie in Férussac, 1826 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Colubridae (Family)

Oligodus
     Oligodus Rafinesque, 1815 accepted as Oligodus Rafinesque, 1815 · Animalia (Kingdom) > Cnidaria (Phylum) > Cnidaria (awaiting allocation) (Class) > Cnidaria (awaiting allocation) (Order) > Cnidaria (awaiting allocation) (Family)
     Oligodus Cooper, 1939 † · Animalia (Kingdom) > Chordata (Phylum) > Conodonta (Class) > Conodontophorida (Order) > Conodonta (awaiting allocation) (Family)

Oligolepis
     Oligolepis Levinsen, 1887 · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Phyllodocida (Order) > Polynoidae (Family)
     Oligolepis Kolbe, 1914 accepted as Oligolepis Kolbe, 1914 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Oligolepis Bleeker, 1874 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Gobiidae (Family)
     Oligolepis Boulenger, 1895 accepted as Oligolepis Boulenger, 1895 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Colubridae (Family)
 Oligolepis Brenske, 1903 accepted as Afrolepis Decelle, 1968 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Oligonema
 Oligonema S. Watson, 1891 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
     Oligonema Rostafinski, 1875 · Protozoa (Kingdom) > Amoebozoa (Phylum) > Myxogastrea (Class) > Trichiida (Order) > Trichiidae (Family)

Oligoneura
     Oligoneura Bigot, 1878 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Acroceridae (Family)
 Oligoneura Davis, 1978 accepted as Manoneura Davis, 1979 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Nepticulidae (Family)

Oligoneurisca
     Oligoneurisca Tshernova, 1937 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Ephemeroptera (Order) > Oligoneuriidae (Family)
     Oligoneurisca Lestage, 1938 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Ephemeroptera (Order) > Oligoneuriidae (Family)

Oligoneuroides
     Oligoneuroides Brues, 1910 accepted as Oligoneuroides Brues, 1910 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
     Oligoneuroides Zhang, 1985 accepted as Oligoneuroides Zhang, 1985 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)

Oligonila
     Oligonila Theobald, 1937 † accepted as Oligonila Theobald, 1937 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Oligonila Carpenter, 1992 † accepted as Oligonila Carpenter, 1992 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)

Oligonyx
     Oligonyx Sugi in Inoue & Kawabe, 1982 accepted as Oligonyx Sugi in Inoue & Kawabe, 1982 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Oligonyx Saussure, 1869 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Mantodea (Order) > Thespidae (Family)

Oligophlebia
     Oligophlebia Hampson, 1893 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Sesiidae (Family)
 Oligophlebia Demoulin, 1965 † accepted as Paraleptophlebia Lestage, 1917 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Ephemeroptera (Order) > Leptophlebiidae (Family)

Oligoplectrum
     Oligoplectrum McLachlan, 1868 accepted as Oligoplectrum McLachlan, 1868 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Trichoptera (Order) > Brachycentridae (Family)
     Oligoplectrum Förster, 1868 accepted as Oligoplectrum Förster, 1868 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)

Oligopleura
     Oligopleura Herrich-Schäffer, 1856 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
 Oligopleura † accepted as Oligopleurus Thiollière, 1850 † · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Semionotiformes (Order) > Semionotiformes (awaiting allocation) (Family)

Oligoporus
     Oligoporus Meek & Worthen, 1862 † · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Echinocystitoida (Order) > Palaechinidae (Family)
     Oligoporus Brefeld, 1888 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Polyporales (Order) > Polyporaceae (Family)

Oligopus
     Oligopus Kirsch, 1875 accepted as Oligopus Kirsch, 1875 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Oligopus Risso, 1810 accepted as Grammonus Gill, 1896 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Ophidiiformes (Order) > Bythitidae (Family)
 Oligopus Minding, 1832 accepted as Grammonus Gill, 1896 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Ophidiiformes (Order) > Bythitidae (Family)

Oligorhina
     Oligorhina Fairmaire & Germain, 1863 accepted as Oligorhina Fairmaire & Germain, 1863 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
 Oligorhina Hull, 1937 accepted as Rhinoprosopa Hull, 1942 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Syrphidae (Family)

Oligorus
     Oligorus Dejean, 1834 accepted as Oligorus Dejean, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
 Oligorus Günther, 1859 accepted as Maccullochella Whitley, 1929 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Serranidae (Family)

Oligosiphonia
     Oligosiphonia J.E. Gray, 1864 accepted as Oligosiphonia J.E. Gray, 1864 (unassessed) · Plantae (Kingdom) > Rhodophyta (Phylum) > Florideophyceae (Class) > Ceramiales (Order) > Rhodomelaceae (Family)
     Oligosiphonia J. Agardh accepted as Oligosiphonia J. Agardh · Plantae (Kingdom) > Rhodophyta (Phylum) > Rhodophyta incertae sedis (Class) > Rhodophyceae (awaiting allocation) (Order) > Rhodophyceae incertae sedis (Family)

Oligostemon
     Oligostemon Turczaninow, 1858 accepted as Oligostemon Turczaninow, 1858 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Proteales (Order) > Sabiaceae (Family)
 Oligostemon Bentham in Bentham & J.D. Hooker, 1865 accepted as Duparquetia Baillon, 1865 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)

Oligotoma
     Oligotoma Westwood, 1836 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Embiodea (Order) > Oligotomidae (Family)
 Oligotoma Bellardi, 1875 † accepted as Asthenotoma Harris & Burrows, 1891 † (Invalid: junior homonym of Oligotoma Westwood, 1836; Asthenotoma is a replacement name) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Neogastropoda (Order) > Borsoniidae (Family)

Oligotomus
     Oligotomus Cope, 1873 † accepted as Oligotomus Cope, 1873 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
 Oligotomus Iredale, 1937 † accepted as Scoteanax Troughton, 1943 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Chiroptera (Order) > Vespertilionidae (Family)

Oligotyphlus
 Oligotyphlus Scheerpeltz, 1940 accepted as Gynotyphlus Coiffait, 1955 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
 Oligotyphlus Scheerpeltz, 1956 accepted as Gynotyphlus Coiffait, 1955 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)

Oligura
     Oligura Rüppell, 1845 accepted as Oligura Rüppell, 1845 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
 Oligura Hodgson, 1845 accepted as Tesia Hodgson, 1837 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Sylviidae (Family)
     Oligura Hodgson, 1844 accepted as Tesia Hodgson, 1837 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Sylviidae (Family)

Olina
     Olina Robineau-Desvoidy, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Sphaeroceridae (Family)
 Olina Walker, 1869 accepted as Aphra Watson in Watson, Fletcher & Nye, 1980 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Arctiidae (Family)
 Olina Doubleday in Doubleday & Westwood, 1848 accepted as Vila Kirby, 1871 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Nymphalidae (Family)

Olinx
 Olinx Mayr, 1878 accepted as Olinx Mayr, 1878 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Eulophidae (Family)
     Olinx McLachlan, 1868 accepted as Olinx McLachlan, 1868 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Trichoptera (Order) > Conoesucidae (Family)

Olisthaerus
     Olisthaerus Heer, 1839 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
     Olisthaerus Dejean, 1833 accepted as Olisthaerus Heer, 1839 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)

Olistherus
 Olistherus Seidlitz, 1872 accepted as Stilbus Seidlitz, 1872 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Phalacridae (Family)
 Olistherus Gemminger & Harold, 1868 accepted as Olisthaerus Dejean, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
 Olistherus Agassiz, 1846 accepted as Olisthaerus Dejean, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)

Olivanites
     Olivanites Troost, 1850 † accepted as Olivanites Troost, 1850 † · Animalia (Kingdom) > Echinodermata (Phylum) > Echinodermata (awaiting allocation) (Class) > Echinodermata (awaiting allocation) (Order) > Echinodermata (awaiting allocation) (Family)
     Olivanites Lyon, 1857 † accepted as Olivanites Lyon, 1857 † (unassessed) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinodermata (awaiting allocation) (Class) > Echinodermata (awaiting allocation) (Order) > Echinodermata (awaiting allocation) (Family)

Oliverella
     Oliverella Van Tieghem, 1895 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Santalales (Order) > Loranthaceae (Family)
 Oliverella J.N. Rose, 1903 accepted as Echeveria A.P. de Candolle, 1828 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Saxifragales (Order) > Crassulaceae (Family)

Oliveria
 Oliveria A. Nayal, 1935 accepted as · Plantae (Kingdom) > Chlorophyta (Phylum) > Chlorophyceae (Class) > Chaetophorales (Order) > Chaetophoraceae (Family)
     Oliveria Sutherland, 1965 † · Animalia (Kingdom) > Cnidaria (Phylum) > Anthozoa (Class) > Rugosa (Order) > Rugosa (awaiting allocation) (Family)
     Oliveria Ventenat, 1801 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Apiales (Order) > Apiaceae (Family)
 Oliveria Gossot ex J. Marnier-Lapostolle, 1949 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Saxifragales (Order) > Crassulaceae (Family)
 Oliveria Sæther, 1976 accepted as Oliveridia Sæther, 1980 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Chironomidae (Family)

Olivia
 Olivia Bertoloni, 1810 accepted as · Plantae (Kingdom) > Chlorophyta (Phylum) > Ulvophyceae (Class) > Dasycladales (Order) > Dasycladaceae (Family)
 Olivia S.F. Gray, 1821 accepted as · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Agaricales (Order) > Hygrophoraceae (Family)
 Olivia Cantraine, 1835 accepted as Danilia Brusina, 1865 (invalid: junior homonym of Olivia Bertolini, 1810 [?Porifera]) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Vetigastropoda (Order) > Chilodontaidae (Family)

Olivieria
     Olivieria Brink, 1965 † accepted as Olivieria Brink, 1965 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Therapsida (Order) > Therapsida (awaiting allocation) (Family)
     Olivieria Robineau-Desvoidy, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Tachinidae (Family)
     Olivieria Meigen, 1838 accepted as Olivieria Meigen, 1838 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Diptera (awaiting allocation) (Family)

Olivierus
     Olivierus Farzanpay, 1987 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Scorpiones (Order) > Buthidae (Family)
     Olivierus Farzanpay, 1986 accepted as Olivierus Farzanpay, 1987 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Scorpiones (Order) > Buthidae (Family)

Olivina
     Olivina d'Orbigny, 1841 accepted as Olivina d'Orbigny, 1841 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Olivina Mörch, 1852 accepted as Olivina Mörch, 1852 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Olivina Frenzel, 1897 accepted as Olivina Frenzel, 1897 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)

Olla
     Olla Velenovský, 1934 · Fungi (Kingdom) > Ascomycota (Phylum) > Leotiomycetes (Class) > Helotiales (Order) > Hyaloscyphaceae (Family)
     Olla Casey, 1899 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coccinellidae (Family)
 Olla Koshevoj, 1987 † accepted as Ollella Aescht, 2001 † · Chromista (Kingdom) > Ciliophora (Phylum) > Ciliophora (awaiting allocation) (Class) > Ciliophora (awaiting allocation) (Order) > Ciliophora (awaiting allocation) (Family)

Olliffia
     Olliffia Fuller, 1899 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Eriococcidae (Family)
     Olliffia Fuller, 1897 accepted as Olliffia Fuller, 1899 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Eriococcidae (Family)

Ollula
     Ollula F. Góczán, 1962 † · Chromista (Kingdom) > Miozoa (Phylum) > Dinophyceae (Class) > Dinophyceae incertae sedis (Order) > Questionable dinoflagellates (Fensome et al.) (Family)
 Ollula Léveillé, 1863 accepted as Tubercularia Tode, 1790 · Fungi (Kingdom) > Ascomycota (Phylum) > Sordariomycetes (Class) > Hypocreales (Order) > Nectriaceae (Family)

Olmeca
     Olmeca T.R. Soderstrom, 1982 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Poales (Order) > Poaceae (Family)
     Olmeca Lamothe-Argumedo & Pineda-López, 1990 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Opisthorchiida (Order) > Cryptogonimidae (Family)

Ologlyptus
     Ologlyptus Lacordaire, 1859 accepted as Ologlyptus Lacordaire, 1859 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)
 Ologlyptus LeConte, 1858 accepted as Stenosides Solier, 1836 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Ololygon
     Ololygon Fitzinger, 1843 accepted as Ololygon Fitzinger, 1843 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Anura (Order) > Hylidae (Family)
     Ololygon Cabanis & Heine, 1863 accepted as Ololygon Cabanis & Heine, 1863 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Olonia
     Olonia Muir, 1925 accepted as Olonia Muir, 1925 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Cixiidae (Family)
     Olonia Stål, 1862 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Eurybrachidae (Family)

Olophorus
 Olophorus Ashmead, 1900 accepted as Otlophorus Förster, 1868 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Ichneumonidae (Family)
 Olophorus accepted as Oplophorus H. Milne Edwards, 1837 [in H. Milne Edwards, 1834-1840] · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Oplophoridae (Family)

Olostoma
 Olostoma Sonsino, 1894 accepted as Strigea Abildgaard, 1790 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Strigeidida (Order) > Strigeidae (Family)
 Olostoma Cossmann, 1925 † accepted as Otostoma d'Archiac, 1856 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Archaeogastropoda (Order) > Archaeogastropoda (awaiting allocation) (Family)

Olotelus
     Olotelus Solier in Gay, 1851 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Elateridae (Family)
 Olotelus Mulsant & Rey, 1866 accepted as Otolelus Klinger, 2000 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Aderidae (Family)

Oltinomys
     Oltinomys Stehlin in Erni, 1942 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Theridomyidae (Family)
     Oltinomys Stehlin & Schaub, 1951 † accepted as Oltinomys Stehlin & Schaub, 1951 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)

Olveria
     Olveria Thapar & Singha [=Sinha], 1946 accepted as Olveria Thapar & Singha [=Sinha], 1946 (unassessed) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Trematoda (awaiting allocation) (Order) > Trematoda (awaiting allocation) (Family)
     Olveria Sinha, 1941 accepted as Olveria Sinha, 1941 (unassessed) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Trematoda (awaiting allocation) (Order) > Trematoda (awaiting allocation) (Family)

Olygodon
     Olygodon Ameghino, 1883 † accepted as Olygodon Ameghino, 1883 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
 Olygodon accepted as Oligodon Boie in Férussac, 1826 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Colubridae (Family)

Olympia
     Olympia Risso, 1826 accepted as Olympia Risso, 1826 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Crustacea (awaiting allocation) (Class) > Crustacea (awaiting allocation) (Order) > Crustacea (awaiting allocation) (Family)
 Olympia Spach, 1836 accepted as Hypericum Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malpighiales (Order) > Hypericaceae (Family)
 Olympia Vest, 1867 accepted as Olympicola Hesse, 1916 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Clausiliidae (Family)

Olynthus
     Olynthus Hübner, 1819 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lycaenidae (Family)
 Olynthus Sørensen, 1932 accepted as Spinopilar Mello-Leitão, 1940 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Opiliones (Order) > Gonyleptidae (Family)
 Olynthus Haeckel, 1869 accepted as Leucosolenia Bowerbank, 1864 (junior synonym) · Animalia (Kingdom) > Porifera (Phylum) > Calcarea (Class) > Leucosolenida (Order) > Leucosoleniidae (Family)

Olyra
     Olyra Linnaeus, 1759 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Poales (Order) > Poaceae (Family)
     Olyra McClelland, 1842 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Siluriformes (Order) > Olyridae (Family)
 Olyra Wallengren, 1865 accepted as Euwallengrenia Fletcher, 1968 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lasiocampidae (Family)

Omala
     Omala Schumacher, 1817 · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Tellinidae (Family)
 Omala Motschoulsky, 1844 accepted as Bembidion Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Omalanthus
 Omalanthus Lessing, 1832 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
 Omalanthus A.H.L. Jussieu, 1824 accepted as Homalanthus A.H.L. Jussieu, 1824 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malpighiales (Order) > Euphorbiaceae (Family)

Omalia
     Omalia Beneden & Coemans, 1867 † accepted as Omalia Beneden & Coemans, 1867 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Cnemidolestodea (Order) > Omaliidae (Family)
     Omalia Ryckholt, 1853 † accepted as Omalia Ryckholt, 1853 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Omalia S.E. Bridel, 1827 accepted as Omalia S.E. Bridel, 1827 (unassessed) · Plantae (Kingdom) > Bryophyta (Phylum) > Bryopsida (Class) > Isobryales (Order) > Neckeraceae (Family)

Omalisus
     Omalisus Geoffroy, 1762 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Omalisidae (Family)
 Omalisus Fourcroy, 1785 accepted as Omalisus Geoffroy, 1762 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Omalisidae (Family)

Omalocephala
     Omalocephala Spinola, 1839 accepted as Omalocephala Spinola, 1839 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Omalocephala Macquart, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Lauxaniidae (Family)

Omalodera
 Omalodera Reitter, 1896 accepted as Maladera Mulsant & Rey, 1871 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Omalodera Hombron & Jacquinot in d'Urville, 1853 accepted as Aemalodera Solier in Gay, 1849 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Omalodera Blanchard, 1853 accepted as Aemalodera Solier in Gay, 1849 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Omalodes
     Omalodes Dejean, 1833 accepted as Omalodes Dejean, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Histeridae (Family)
 Omalodes Erichson in Klug, 1834 accepted as Omalodes Dejean, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Histeridae (Family)

Omaloplia
     Omaloplia Schönherr, 1817 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Omaloplia Dejean, 1821 accepted as Omaloplia Schönherr, 1817 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Omaloplia Stephens accepted as Homaloplia Stephens, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Omalosoma
     Omalosoma Walker, 1856 accepted as Omalosoma Walker, 1856 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Omalosoma Dufour, 1820 accepted as Omalosoma Dufour, 1820 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Arachnida (awaiting allocation) (Order) > Arachnida (awaiting allocation) (Family)
     Omalosoma Gory, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
     Omalosoma Boisduval, 1835 accepted as Omalosoma Boisduval, 1835 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)

Omalostoma
     Omalostoma Rondani, 1862 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Tachinidae (Family)
 Omalostoma Graff, 1882 accepted as Omalostomum Beneden, 1870 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Turbellaria (Class) > Macrostomida (Order) > Macrostomidae (Family)

Omalus
     Omalus Panzer, 1801 accepted as Omalus Panzer, 1801 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
 Omalus Allard, 1876 accepted as Cylindronotus Faldermann, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Omalysus
 Omalysus Hope, 1831 accepted as Omalisus Geoffroy, 1762 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Omalisidae (Family)
 Omalysus Trost, 1801 accepted as Omalisus Geoffroy, 1762 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Omalisidae (Family)

Omanana
     Omanana DeLong, 1941 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Cicadellidae (Family)
 Omanana accepted as Omonana Just & Wilson, 2004 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Isopoda (Order) > Paramunnidae (Family)

Omania
     Omania Popov, 1980 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Pamphagidae (Family)
 Omania S. Moore, 1901 accepted as Lindenbergia J.G.C. Lehmann, 1829 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Orobanchaceae (Family)
     Omania Horváth, 1915 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Omaniidae (Family)

Omaseus
     Omaseus Mannerheim, 1824 accepted as Omaseus Mannerheim, 1824 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
     Omaseus Dejean, 1821 accepted as Pterostichus Bonelli, 1810 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Omaseus accepted as Pterostichus Bonelli, 1810 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Omaspides
     Omaspides Boheman, 1850 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Omaspides Chevrolat in Dejean, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Omaspides Dejean, 1835 accepted as Omaspides Boheman, 1850 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Ombria
     Ombria Quenstedt, 1873 accepted as Ombria Quenstedt, 1873 (unassessed) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinodermata (awaiting allocation) (Class) > Echinodermata (awaiting allocation) (Order) > Echinodermata (awaiting allocation) (Family)
     Ombria Eschscholtz, 1831 accepted as Ombria Eschscholtz, 1831 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Ombrophila
     Ombrophila E.M. Fries, 1849 · Fungi (Kingdom) > Ascomycota (Phylum) > Leotiomycetes (Class) > Helotiales (Order) > Helotiaceae (Family)
     Ombrophila Singer, 1936 · Fungi (Kingdom) > Fungi (awaiting allocation) (Phylum) > Fungi (awaiting allocation) (Class) > Fungi (awaiting allocation) (Order) > Fungi (awaiting allocation) (Family)
     Ombrophila Quélet, 1892 · Fungi (Kingdom) > Fungi (awaiting allocation) (Phylum) > Fungi (awaiting allocation) (Class) > Fungi (awaiting allocation) (Order) > Fungi (awaiting allocation) (Family)

Omega
     Omega B.C. Sutton & D.W. Minter, 1988 · Fungi (Kingdom) > Ascomycota (Phylum) > Ascomycota incertae sedis (Class) > Ascomycota incertae sedis (Order) > Ascomycota incertae sedis (Family)
     Omega Saussure, 1854 accepted as Omega Saussure, 1854 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)

Omeia
     Omeia Hsü, 1933 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Spirurida (Order) > Quimperiidae (Family)
 Omeia Chen, 1934 accepted as Omeiana Chen, 1934 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Omia
     Omia Hübner, 1821 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
     Omia Guenée, 1850 accepted as Omia Guenée, 1850 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
 Omia Annandale, 1919 accepted as Biwakoia Burch, 1968 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Hygrophila (Order) > Lymnaeidae (Family)

Omias
     Omias Germar, 1817 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Omias Wollaston, 1854 accepted as Laparocerus Schönherr, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Omias Seidlitz, 1868 accepted as Omiamima Silfverberg, 1977 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Omiodes
     Omiodes Guenée, 1854 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Crambidae (Family)
     Omiodes Felder, 1875 accepted as Omiodes Felder, 1875 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)

Omiza
     Omiza Walker in Tennent, 1859 accepted as Omiza Walker in Tennent, 1859 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
     Omiza Walker, 1862 accepted as Omiza Walker, 1862 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)

Ommatissus
     Ommatissus Fieber, 1875 accepted as Ommatissus Fieber, 1875 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Tropiduchidae (Family)
     Ommatissus Fieber, 1872 accepted as Ommatissus Fieber, 1872 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Tropiduchidae (Family)

Ommatolampes
     Ommatolampes Fischer-Waldheim, 1851 accepted as Ommatolampes Fischer-Waldheim, 1851 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Pisces (awaiting allocation) (Class) > Pisces (awaiting allocation) (Order) > Pisces (awaiting allocation) (Family)
     Ommatolampes Schönherr, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Dryophthoridae (Family)

Ommatolampus
 Ommatolampus Schönherr, 1845 accepted as Ommatolampes Schönherr, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Dryophthoridae (Family)
 Ommatolampus Pascoe, 1887 accepted as Ommatolampes Schönherr, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Dryophthoridae (Family)

Ommatophora
     Ommatophora Guenée, 1852 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
 Ommatophora Turner, 1848 accepted as Ommatophoca Gray, 1844 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Phocidae (Family)

Ommatoplea
     Ommatoplea Ehrenberg, 1831 · Animalia (Kingdom) > Nemertea (Phylum) > Enopla (Class) > Hoplonemertea (Order) > Amphiporidae (Family)
 Ommatoplea Diesing, 1862 accepted as (nomen oblitum) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Platyhelminthes incertae sedis (Class) > Platyhelminthes incertae sedis (Order) > Platyhelminthes incertae sedis (Family)

Ommatoptera
     Ommatoptera Herrich-Schäffer, 1856 accepted as Ommatoptera Herrich-Schäffer, 1856 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Ommatoptera Pictet, 1888 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tettigoniidae (Family)

Ommatostrephes
 Ommatostrephes Agassiz, 1846 accepted as Ommastrephes d'Orbigny [in 1834-1847], 1834 · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Teuthoidea (Order) > Ommastrephidae (Family)
 Ommatostrephes Loven, 1845 accepted as Ommastrephes d'Orbigny [in 1834-1847], 1834 (emmendation of Ommastrephes) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Teuthoidea (Order) > Ommastrephidae (Family)

Omniglypta
     Omniglypta Kuroda & Habe in Habe, 1953 · Animalia (Kingdom) > Mollusca (Phylum) > Scaphopoda (Class) > Dentaliida (Order) > Omniglyptidae (Family)
     Omniglypta Pilsbry, 1905 · Animalia (Kingdom) > Mollusca (Phylum) > Scaphopoda (Class) > Dentaliida (Order) > Omniglyptidae (Family)

Omobranchus
     Omobranchus Valenciennes in Cuvier & Valenciennes, 1836 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Blenniidae (Family)
     Omobranchus Ehrenberg, 1836 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Blenniidae (Family)

Omobrus
     Omobrus Andrewes, 1930 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
     Omobrus Steven or Fischer Waldheim, 1829 accepted as Omobrus Steven or Fischer Waldheim, 1829 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)

Omocera
     Omocera Lioy, 1864 accepted as Omocera Lioy, 1864 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Diptera (awaiting allocation) (Family)
     Omocera Dejean, 1835 accepted as Omocera Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Omocera Blanchard in d'Orbigny, 1846 accepted as Omocera Blanchard in d'Orbigny, 1846 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
 Omocera Chevrolat, 1835 accepted as Omocerus Chevrolat, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Omochaeta
     Omochaeta Duda, 1930 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Chloropidae (Family)
 Omochaeta Diakonoff, 1966 accepted as Alischirnevaia Koçak, 1981 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Tortricidae (Family)

Omocrates
     Omocrates Burmeister, 1844 accepted as Omocrates Burmeister, 1844 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Omocrates Mulsant & Rey, 1854 accepted as Phylan Stephens, 1832 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Omoiosia
     Omoiosia Canu & Bassler, 1927 † accepted as Omoiosia Canu & Bassler, 1927 † (unassessed) · Animalia (Kingdom) > Bryozoa (Phylum) > Gymnolaemata (Class) > Cheilostomatida (Order) > Membranicellariidae (Family)
     Omoiosia Canu & Lecointre, 1925 † accepted as Omoiosia Canu & Lecointre, 1925 † · Animalia (Kingdom) > Bryozoa (Phylum) > Gymnolaemata (Class) > Cheilostomatida (Order) > Membranicellariidae (Family)

Omophlus
 Omophlus Dahl, 1823 accepted as Omophlus Dahl, 1823 (Published in a suppressed work (ICZN)) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)
     Omophlus Dejean, 1834 accepted as Omophlus Dejean, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Omophlus Solier, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Omophoita
     Omophoita Dejean, 1835 accepted as Omophoita Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Omophoita Chevrolat, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Omoplata
     Omoplata Lacordaire, 1872 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Omoplata Hope, 1840 accepted as Echoma Chevrolat in Dejean, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Omorgus
     Omorgus Erichson, 1847 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Trogidae (Family)
     Omorgus Förster, 1868 accepted as Omorgus Förster, 1868 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)

Omosaurus
     Omosaurus Leidy, 1857 † accepted as Omosaurus Leidy, 1857 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)
 Omosaurus Owen, 1875 † accepted as Dacentrurus Lucas, 1902 † · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Ornithischia (Order) > Stegosauridae (Family)

Omosita
     Omosita Erichson in Germar, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Nitidulidae (Family)
 Omosita Simon, 1864 accepted as Loxosceles Heineken & Lowe, 1832 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Loxoscelidae (Family)

Omoteina
     Omoteina Dejean, 1835 accepted as Omoteina Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Omoteina Blanchard, 1845 accepted as Omoteina Blanchard, 1845 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Omoteina Chevrolat, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Omototus
     Omototus Dejean, 1835 accepted as Omototus Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Omototus Clark, 1860 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Omphalaria
 Omphalaria A. Massalongo, 1855 accepted as Anema Nylander ex K.B.J. Forssell, 1885 · Fungi (Kingdom) > Ascomycota (Phylum) > Lichinomycetes (Class) > Lichinales (Order) > Lichinaceae (Family)
 Omphalaria R. Girard & Dunal ex Nylander, 1855 accepted as Thyrea A. Massalongo, 1856 · Fungi (Kingdom) > Ascomycota (Phylum) > Lichinomycetes (Class) > Lichinales (Order) > Lichinaceae (Family)

Omphale
     Omphale Haliday, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Eulophidae (Family)
     Omphale Haliday in Curtis, 1829-30 accepted as Omphale Haliday, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Eulophidae (Family)

Omphalia
     Omphalia Boisduval in Herrich-Schaefer, 1854 accepted as Omphalia Boisduval in Herrich-Schaefer, 1854 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Omphalia Haan, 1825 accepted as Omphalia Haan, 1825 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Gastropoda (awaiting allocation) (Order) > Gastropoda (awaiting allocation) (Family)
 Omphalia Meek, 1876 accepted as Omphiscola Rafinesque, 1819 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Hygrophila (Order) > Lymnaeidae (Family)
 Omphalia (E.M. Fries) Staude, 1857 accepted as Omphalina Quélet, 1886 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Agaricales (Order) > Tricholomataceae (Family)
 Omphalia Zekeli, 1852 † accepted as Cassiope Coquand, 1865 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Sorbeoconcha (Order) > Turritellidae (Family)
 Omphalia (Persoon) S.F. Gray, 1821 accepted as Pseudoclitocybe (Singer) Singer, 1956 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Agaricales (Order) > Tricholomataceae (Family)

Omphalina
     Omphalina Quélet, 1886 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Agaricales (Order) > Tricholomataceae (Family)
     Omphalina Rafinesque, 1831 accepted as Omphalina Rafinesque, 1831 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Zonitidae (Family)

Omphalius
     Omphalius Philippi, 1847 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Vetigastropoda incertae sedis (Order) > Tegulidae (Family)
     Omphalius Vachal, 1900 accepted as Omphalius Vachal, 1900 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
 Omphalius Abeille de Perrin, 1891 accepted as Anthocomus Erichson, 1840 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Melyridae (Family)
 Omphalius Roussel, 1806 accepted as Pseudoclitocybe (Singer) Singer, 1956 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Agaricales (Order) > Tricholomataceae (Family)

Omphalodium
     Omphalodium J. Meyen & Flotow, 1843 · Fungi (Kingdom) > Ascomycota (Phylum) > Lecanoromycetes (Class) > Lecanorales (Order) > Parmeliaceae (Family)
 Omphalodium Rabenhorst, 1845 accepted as Umbilicaria G.F. Hoffmann, 1789 · Fungi (Kingdom) > Ascomycota (Phylum) > Lecanoromycetes (Class) > Umbilicariales (Order) > Umbilicariaceae (Family)

Omphalophora
     Omphalophora Becker, 1900 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Rhagionidae (Family)
     Omphalophora Hampson in Romanoff, 1901 accepted as Omphalophora Hampson in Romanoff, 1901 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)

Omphalopsis
     Omphalopsis Greville, 1863 · Chromista (Kingdom) > Ochrophyta (Phylum) > Bacillariophyceae (Class) > Cymatosirales (Order) > Cymatosiraceae (Family)
 Omphalopsis F.S. Earle, 1909 accepted as Xeromphalina Kühner & Maire in Konrad & Maublanc, 1934 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Agaricales (Order) > Mycenaceae (Family)

Omphalostyla
     Omphalostyla Adams, 1855 accepted as Omphalostyla Adams, 1855 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Omphalostyla Schlüter, 1838 accepted as Omphalostyla Schlüter, 1838 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Omphalotheca
 Omphalotheca Hasskarl, 1866 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Commelinales (Order) > Commelinaceae (Family)
     Omphalotheca Ehrenberg, 1854 · Chromista (Kingdom) > Ochrophyta (Phylum) > Bacillariophyceae (Class) > Bacillariophyceae (awaiting allocation) (Order) > Bacillariophyceae (awaiting allocation) (Family)

Omphra
     Omphra Reiche, 1842 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
     Omphra Dejean, 1821 accepted as Omphra Reiche, 1842 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Omura
     Omura Walker, 1870 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Pyrgomorphidae (Family)
 Omura Peckham, 1894 accepted as Ceriomura Simon, 1901 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Salticidae (Family)

Ona
     Ona Metcalf, 1954 accepted as Ona Metcalf, 1954 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Derbidae (Family)
 Ona P. Ravenna, 1972 accepted as Olsynium Rafinesque, 1836 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Iridaceae (Family)

Onca
     Onca Menge in Berendt, 1854 accepted as Onca Menge in Berendt, 1854 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Arachnida (awaiting allocation) (Order) > Arachnida (awaiting allocation) (Family)
     Onca Severtzov, 1858 accepted as Onca Severtzov, 1858 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)

Oncaea
     Oncaea Philippi, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Maxillopoda (Class) > Cyclopoida (Order) > Oncaeidae (Family)
 Oncaea Gistl, 1847 accepted as Achatina Lamarck, 1799 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Achatinidae (Family)

Onceropyga
     Onceropyga Turner, 1906 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Zygaenidae (Family)
 Onceropyga Ferris, 1955 accepted as Oregmopyga · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Eriococcidae (Family)

Onchidium
     Onchidium Buchannan, 1800 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Systellommatophora (Order) > Onchidiidae (Family)
     Onchidium Cuvier, 1805 accepted as Onchidium Cuvier, 1805 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Onchidoris
     Onchidoris Blainville, 1816 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Nudibranchia (Order) > Onchidorididae (Family)
 Onchidoris Winckworth, 1932 accepted as Onchidoris Blainville, 1816 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Nudibranchia (Order) > Onchidorididae (Family)

Onchocephala
     Onchocephala Guérin-Ménéville, 1844 accepted as Onchocephala Guérin-Ménéville, 1844 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Onchocephala Dejean, 1835 accepted as Onchocephala Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
 Onchocephala Weise, 1911 accepted as Oncocephala Agassiz, 1846 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Onchocephalites
     Onchocephalites Rasetti, 1957 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Ptychopariida (Order) > Ptychopariida (awaiting allocation) (Family)
     Onchocephalites Tomaspol'skaya in Bognibova, 1965 † accepted as Onchocephalites Tomaspol'skaya in Bognibova, 1965 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Trilobita (awaiting allocation) (Order) > Trilobita (awaiting allocation) (Family)

Onchocephalus
     Onchocephalus Resser, 1937 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Ptychopariida (Order) > Ptychopariidae (Family)
 Onchocephalus Chevrolat, 1847 accepted as Oncocephala Agassiz, 1846 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Onchofora
 Onchofora Krøyer, 1852-53 accepted as Oncophora Diesing, 1851 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Spirurida (Order) > Camallanidae (Family)
 Onchofora Kroy, 1852 accepted as Oncophora Diesing, 1851 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Spirurida (Order) > Camallanidae (Family)

Onchophora
     Onchophora Diesling, 1851 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Spirurida (Order) > Camallanidae (Family)
 Onchophora Krøyer, 1840 accepted as Oncophora Diesing, 1851 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Spirurida (Order) > Camallanidae (Family)

Onchoscelis
     Onchoscelis Schönherr, 1844 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Onchoscelis Dejean, 1835 accepted as Onchoscelis Schönherr, 1844 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Onchoscelis Dejean, 1836 accepted as Onchoscelis Schönherr, 1844 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Oncidiella
     Oncidiella Hort., 1984 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Oncidiella P. Fischer & Crosse, 1878 accepted as Onchidella J.E. Gray, 1850 (Invalid: unjustified emendation of Onchidella) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Systellommatophora (Order) > Onchidiidae (Family)

Oncidium
     Oncidium O. Swartz, 1800 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Oncidium C.G.D. Nees in G. Kunze & J.C. Schmidt, 1823 accepted as Myxotrichum G. Kunze, 1823 · Fungi (Kingdom) > Ascomycota (Phylum) > Dothideomycetes (Class) > Dothideomycetes incertae sedis (Order) > Myxotrichaceae (Family)
 Oncidium Agassiz, 1846 accepted as Onchidium Buchannan, 1800 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Systellommatophora (Order) > Onchidiidae (Family)

Oncidodontopsis
     Oncidodontopsis J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Oncidodontopsis J.M.H. Shaw, 2004 accepted as Oncidodontopsis J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Oncidopsiella
     Oncidopsiella J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Oncidopsiella J.M.H. Shaw, 2004 accepted as Oncidopsiella J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Oncidopsis
     Oncidopsis J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Oncidopsis J.M.H. Shaw, 2004 accepted as Oncidopsis J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Oncidumnia
     Oncidumnia J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Oncidumnia J.M.H. Shaw, 2004 accepted as Oncidumnia J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Oncis
 Oncis Plate, 1893 accepted as Platevindex H. B. Baker, 1938 (invalid: junior homonym of Oncis Herrmannsen, 1847) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Systellommatophora (Order) > Onchidiidae (Family)
 Oncis Herrmannsen, 1847 accepted as Peronia Fleming, 1822 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Systellommatophora (Order) > Onchidiidae (Family)

Oncobothrium
 Oncobothrium Agassiz, 1846 accepted as Onchobothrium de Blainville, 1828 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Cestoda (Class) > Tetraphyllidea (Order) > Onchobothriidae (Family)
 Oncobothrium de Blainville, 1828 accepted as Onchobothrium de Blainville, 1828 (misspelling) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Cestoda (Class) > Tetraphyllidea (Order) > Oncobothriidae (Family)

Oncobyrsa
 Oncobyrsa Meneghini, 1842 accepted as Hydrococcus Kützing, 1833 · Bacteria (Kingdom) > Cyanobacteria (Phylum) > Cyanophyceae (Class) > Pleurocapsales (Order) > Hydrococcaceae (Family)
 Oncobyrsa C.Agardh, 1827 accepted as Placoma Schousboe ex Bornet & Thuret, 1876 · Bacteria (Kingdom) > Cyanobacteria (Phylum) > Cyanophyceae (Class) > Chroococcales (Order) > Entophysalidaceae (Family)

Oncocephalus
     Oncocephalus Klug in Ehrenberg, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Reduviidae (Family)
 Oncocephalus Fischer, 1813 accepted as Ogcocephalus Fischer, 1813 (misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Lophiiformes (Order) > Ogcocephalidae (Family)

Oncocera
     Oncocera Stephens, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Pyralidae (Family)
     Oncocera Stephens, 1829 accepted as Oncocera Stephens, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Pyralidae (Family)

Oncoderes
 Oncoderes Agassiz, 1846 accepted as Oncoderes Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Oncoderes Agassiz, 1846 accepted as Oncoderes Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Oncoderes Agassiz, 1846 accepted as Oncoderes Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Oncoderes Gemminger & Harold, 1873 accepted as Oncideres Audinet-Serville, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Oncodes
     Oncodes Meigen, 1822 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Acroceridae (Family)
 Oncodes Blanchard in Brullé, 1840 accepted as Ogcodes Latreille, 1796 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Acroceridae (Family)

Oncodiscus
     Oncodiscus Yamaguti, 1934 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Cestoda (Class) > Pseudophyllidea (Order) > Bothriocephalidae (Family)
     Oncodiscus J.W. Bailey accepted as Oncodiscus J.W. Bailey (MS name (?)) · Chromista (Kingdom) > Ochrophyta (Phylum) > Bacillariophyceae (Class) > (Order) > Bacillariophyceae incertae sedis (Family)

Oncodoris
 Oncodoris Agassiz, 1846 accepted as Onchidoris Blainville, 1816 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Nudibranchia (Order) > Onchidorididae (Family)
 Oncodoris Agassiz, 1846 accepted as Onchidoris Blainville, 1816 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Nudibranchia (Order) > Onchidorididae (Family)

Oncognathus
     Oncognathus Fieber, 1858 accepted as Oncognathus Fieber, 1858 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
 Oncognathus Lacordaire, 1854 accepted as Hadrognathus Schaum, 1862 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)

Oncoiulus
 Oncoiulus Verhoeff, 1894 accepted as Unciger Brandt, 1841 · Animalia (Kingdom) > Arthropoda (Phylum) > Diplopoda (Class) > Julida (Order) > Julidae (Family)
     Oncoiulus Verhoeff, 1893 accepted as Unciger Brandt, 1841 · Animalia (Kingdom) > Arthropoda (Phylum) > Diplopoda (Class) > Julida (Order) > Julidae (Family)

Oncoma
     Oncoma Fieber, 1860 accepted as Oncoma Fieber, 1860 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Oncoma A. Sprengel in K.P.J. Sprengel, 1827 accepted as Oncoma A. Sprengel in K.P.J. Sprengel, 1827 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Verbenaceae (Family)
 Oncoma Mayer, 1876 † accepted as Dilatilabrum Cossmann, 1904 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Littorinimorpha (Order) > Strombidae (Family)

Oncomera
     Oncomera Stephens, 1832 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Oedemeridae (Family)
     Oncomera Stephens, 1829 accepted as Oedemera Olivier, 1789 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Oedemeridae (Family)

Oncomerus
     Oncomerus Burmeister, 1835 accepted as Oncomerus Burmeister, 1835 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
 Oncomerus Agassiz, 1846 accepted as Oncomerus Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Onconotus
     Onconotus Fischer de Waldheim, 1839 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tettigoniidae (Family)
 Onconotus Agassiz, 1846 accepted as Toxeutes Newman, 1840 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Oncophora
     Oncophora Bergh, 1853 accepted as Oncophora Bergh, 1853 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Gastropoda (awaiting allocation) (Order) > Gastropoda (awaiting allocation) (Family)
     Oncophora Diesing, 1851 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Spirurida (Order) > Camallanidae (Family)
     Oncophora Schrammen, 1924 † · Animalia (Kingdom) > Porifera (Phylum) > Demospongea (Class) > Lithistida (Order) > Lithistida (awaiting allocation) (Family)
 Oncophora Rzehak, 1882 † accepted as Rzehakia Korobkov, 1954 † · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Veneroida (awaiting allocation) (Family)

Oncophorus
     Oncophorus Glocker, 1850 accepted as Oncophorus Glocker, 1850 (unassessed) · Animalia (Kingdom) > Animalia (awaiting allocation) (Phylum) > Animalia (awaiting allocation) (Class) > Animalia (awaiting allocation) (Order) > Animalia (awaiting allocation) (Family)
     Oncophorus (S.E. Bridel) S.E. Bridel, 1826 · Plantae (Kingdom) > Bryophyta (Phylum) > Bryopsida (Class) > Dicranales (Order) > Dicranaceae (Family)
 Oncophorus Eppelsheim, 1885 accepted as Eppelsheimius Bernhauer, 1915 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
 Oncophorus Piaget, 1880 accepted as Rallicola Johnston & Harrison, 1911 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Phthiraptera (Order) > Philopteridae (Family)
 Oncophorus Rudow, 1870 accepted as Rallicola Johnston & Harrison, 1911 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Phthiraptera (Order) > Philopteridae (Family)

Oncoptera
 Oncoptera Lacordaire, 1869 accepted as Eburodacrys White, 1853 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Oncoptera Meyrick, 1890 accepted as Oncopera Walker, 1856 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Hepialidae (Family)

Oncopterus
     Oncopterus Steindachner, 1874 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Pleuronectiformes (Order) > Pleuronectidae (Family)
 Oncopterus Fairmaire, 1887 accepted as Oncopteryx Gebien, 1943 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Oncopus
     Oncopus Herrich-Schäffer, 1856 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
 Oncopus Cope, 1892 accepted as Oncopus Cope, 1892 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Scincidae (Family)
 Oncopus Thorell, 1876 accepted as Sandokan Özdikmen & Kury, 2007 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Opiliones (Order) > Sandokanidae (Family)

Oncorhinus
     Oncorhinus Blanchard in Gay, 1851 accepted as Oncorhinus Blanchard in Gay, 1851 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Oncorhinus Shuckard in Grey, 1841 accepted as Oncorhinus Shuckard in Grey, 1841 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
     Oncorhinus Schoenherr, 1836 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Oncorhinus Schönherr, 1833 accepted as Oncorhinus Schoenherr, 1836 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Oncorhynchus
     Oncorhynchus Suckley, 1861 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Salmoniformes (Order) > Salmonidae (Family)
     Oncorhynchus J.G.C. Lehmann, 1833 accepted as Oncorhynchus J.G.C. Lehmann, 1833 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Scrophulariaceae (Family)

Oncorrhinus
 Oncorrhinus Dalla Torre, 1894 accepted as Oncorrhinus Dalla Torre, 1894 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
 Oncorrhinus Gemminger & Harold, 1871 accepted as Oncorhinus Schoenherr, 1836 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Oncoscelis
     Oncoscelis Westwood, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Tessaratomidae (Family)
     Oncoscelis Westwood in Hope, 1837 accepted as Oncoscelis Westwood, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Tessaratomidae (Family)
 Oncoscelis Gemminger & Harold, 1871 accepted as Onchoscelis Schönherr, 1844 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Oncoscelis Agassiz, 1846 accepted as Onchoscelis Schönherr, 1844 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Oncosoma
     Oncosoma Westwood, 1842 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)
 Oncosoma Agassiz, 1846 accepted as Oncosoma Westwood, 1842 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Oncostoma
     Oncostoma Brusina, 1893 † accepted as Oncostoma Brusina, 1893 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Oncostoma Sclater, 1862 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Tyrannidae (Family)

Oncostylus
 Oncostylus (Schlechtendal) F. Bolle, 1933 accepted as Geum Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Rosales (Order) > Rosaceae (Family)
 Oncostylus Habu, 1978 accepted as Olisares Motschoulsky, 1864 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Oncotion
 Oncotion Klein, 1777 accepted as Cyclopterus Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Scorpaeniformes (Order) > Cyclopteridae (Family)
 Oncotion Walbaum, 1792 accepted as Cyclopterus Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Scorpaeniformes (Order) > Cyclopteridae (Family)

Oncotus
     Oncotus Solier in Baudi & Truqui, 1848 accepted as Oncotus Solier in Baudi & Truqui, 1848 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Oncotus Dejean, 1834 accepted as Oncotus Dejean, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Oncotus Blanchard, 1845 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Oncotylus
     Oncotylus Fieber, 1858 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Miridae (Family)
 Oncotylus Kützing, 1843 accepted as Gymnogongrus Martius, 1833 (synonym) · Plantae (Kingdom) > Rhodophyta (Phylum) > Florideophyceae (Class) > Gigartinales (Order) > Gigartinaceae (Family)

Oncus
     Oncus Paetel, 1875 accepted as Oncus Paetel, 1875 · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Oncus Agassiz, 1846 † accepted as Onchus Agassiz, 1835 † · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Archaeostraca (Order) > Ceratiocarididae (Family)
 Oncus Agassiz, 1846 accepted as Peronia Fleming, 1822 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Systellommatophora (Order) > Onchidiidae (Family)
 Oncus Loureiro, 1790 accepted as Dioscorea Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Dioscoreales (Order) > Dioscoreaceae (Family)

Oncylotrachelus
 Oncylotrachelus Agassiz, 1846 accepted as Occylotrachelus Schönherr, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Oncylotrachelus Gemminger & Harold, 1871 accepted as Occylotrachelus Schönherr, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Ondatra
     Ondatra Link, 1795 accepted as Ondatra Link, 1795 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Muridae (Family)
 Ondatra Lacepède, 1799 accepted as Ondatra Link, 1795 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Muridae (Family)

Onega
     Onega Distant, 1908 accepted as Onega Distant, 1908 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Onega Fedonkin in Keller & Fedonkin, 1976 † · Animalia (Kingdom) > Arthropoda (Phylum) > Paratrilobita (Class) > Paratrilobita (awaiting allocation) (Order) > Paratrilobita (awaiting allocation) (Family)

Oniella
     Oniella Matsumura, 1912 accepted as Oniella Matsumura, 1912 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
 Oniella † accepted as Onniella Bancroft, 1928 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Rhynchonellata (Class) > Orthida (Order) > Dalmanellidae (Family)

Oniscidia
     Oniscidia Swainson, 1840 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Neogastropoda (Order) > Harpidae (Family)
 Oniscidia Mörch, 1852 accepted as Morum Röding, 1798 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Neogastropoda (Order) > Harpidae (Family)

Oniscomorpha
     Oniscomorpha Arrow in Andrews, 1900 accepted as Oniscomorpha Arrow in Andrews, 1900 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
 Oniscomorpha Godeffroy, 1877 accepted as Laxta Walker, 1868 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Blattodea (Order) > Blaberidae (Family)

Oniscosoma
 Oniscosoma Sars, 1851 accepted as Spinther Johnston, 1845 (subjective synonym) · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Spintherida (Order) > Spintheridae (Family)
 Oniscosoma Brunner von Wattenwyl, 1865 accepted as Laxta Walker, 1868 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Blattodea (Order) > Blaberidae (Family)

Oniscus
     Oniscus Linnaeus, 1758 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Isopoda (Order) > Oniscidae (Family)
 Oniscus Baird, Brewer & Ridgway, 1874 accepted as Butorides Blyth, 1852 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Ardeiformes (Order) > Ardeidae (Family)
 Oniscus Lamartiniere, 1781 accepted as Cecrops Leach, 1816 (nom. praeocc.) · Animalia (Kingdom) > Arthropoda (Phylum) > Maxillopoda (Class) > Siphonostomatoida (Order) > Pandaridae (Family)

Oniticellus
     Oniticellus Serville, 1825 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Oniticellus Le Peletier & Audinet-Serville, 1828 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Oniticellus Dejean, 1821 accepted as Oniticellus Serville, 1825 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Onix
 Onix Mayr, 1884 accepted as Onix Mayr, 1884 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
 Onix Medikus, 1787 accepted as Astragalus Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)

Onnia
     Onnia P.A. Karsten, 1889 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Hymenochaetales (Order) > Hymenochaetaceae (Family)
     Onnia Bancroft, 1933 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Asaphida (Order) > Trinucleidae (Family)

Onobroma
     Onobroma J. Gaertner, 1791 accepted as Onobroma J. Gaertner, 1791 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
 Onobroma A.P. de Candolle, 1838 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)

Onocephala
     Onocephala Thomson, 1857 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Onocephala Sturm, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Onocephala Dejean, 1835 accepted as Onocephala Thomson, 1857 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Onoceras
 Onoceras Tate-Woodward, 1868 † accepted as Onoceras Tate-Woodward, 1868 † (Misspelling) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Oncocerida (Order) > Oncoceratidae (Family)
 Onoceras Swartz & Prouty, 1923 † accepted as Onoceras Swartz & Prouty, 1923 † (Misspelling) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Oncocerida (Order) > Oncoceratidae (Family)

Onocrotalus
 Onocrotalus Möhring, 1758 accepted as Onocrotalus Möhring, 1758 (Published in a rejected work (ICZN)) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Onocrotalus Brisson, 1760 accepted as Onocrotalus Brisson, 1760 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Ontaria
     Ontaria Clarke, 1904 accepted as Ontaria Clarke, 1904 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Ontaria Lesson in Férussac, 1826 accepted as Otaria Péron in Péron & Lesueur, 1816 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Otariidae (Family)

Onthocharis
     Onthocharis Westwood, 1847 accepted as Onthocharis Westwood, 1847 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Onthocharis Dejean, 1833 accepted as Onthocharis Dejean, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Onthophilus
     Onthophilus Leach, 1817 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Histeridae (Family)
 Onthophilus Walker, 1872 accepted as Ceuthophilus Scudder, 1862 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Rhaphidophoridae (Family)

Ontolezia
     Ontolezia J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Ontolezia J.M.H. Shaw, 2004 accepted as Ontolezia J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Ontolglossum
     Ontolglossum J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Ontolglossum J.M.H. Shaw, 2004 accepted as Ontolglossum J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Onukia
     Onukia Kobayashi & Hamada, 1976 † accepted as Onukia Kobayashi & Hamada, 1976 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Trilobita (awaiting allocation) (Order) > Trilobita (awaiting allocation) (Family)
     Onukia Matsumura, 1912 accepted as Onukia Matsumura, 1912 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Cicadellidae (Family)

Onus
 Onus Rafinesque, 1810 accepted as Merluccius Rafinesque, 1810 (synonym) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Gadiformes (Order) > Merlucciidae (Family)
 Onus Agassiz, 1846 accepted as Gaidropsarus Rafinesque, 1810 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Gadiformes (Order) > Lotidae (Family)
 Onus A. Gilli, 1971 accepted as Mellera S. Moore, 1879 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Acanthaceae (Family)

Onychaspis
     Onychaspis Stein, 1859 · Chromista (Kingdom) > Ciliophora (Phylum) > Spirotrichea (Class) > Hypotrichida (Order) > Aspidiscidae (Family)
     Onychaspis Raymond, 1925 † accepted as Onychaspis Raymond, 1925 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Trilobita (awaiting allocation) (Order) > Trilobita (awaiting allocation) (Family)

Onychia
     Onychia Jiang, 1982 † accepted as Onychia Jiang, 1982 † (unassessed) · Animalia (Kingdom) > Problematica (Phylum) > Problematica (awaiting allocation) (Class) > Problematica (awaiting allocation) (Order) > Problematica (awaiting allocation) (Family)
     Onychia Hübner, 1825 accepted as Onychia Hübner, 1825 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Onychia Haliday in Curtis, 1829-30 accepted as Onychia Haliday in Curtis, 1829-30 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
     Onychia Sandberger, 1889 accepted as Onychia Sandberger, 1889 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Onychia Blainville, 1823 accepted as Onykia Lesueur, 1821 (Unjustified emendation of Onykia) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Teuthoidea (Order) > Onychoteuthidae (Family)

Onychites
     Onychites Quenstedt, 1856 † · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Belemnoidea incertae sedis (Order) > Belemnoidea incertae sedis (Family)
 Onychites Zakrzewski, 1886 † accepted as Onychites Quenstedt, 1856 † (Later usage of Onychites Quenstedt, 1856) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Belemnoidea incertae sedis (Order) > Belemnoidea incertae sedis (Family)

Onychium
     Onychium Kaulfuss, 1820 · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Polypodiales (Order) > Pteridaceae (Family)
 Onychium Reinwardt, 1825 accepted as Lecanopteris Reinwardt, 1825 · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Polypodiales (Order) > Polypodiaceae (Family)
 Onychium Blume, 1825 accepted as Dendrobium O. Swartz, 1799 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Onychiurus
     Onychiurus Gervais, 1841 · Animalia (Kingdom) > Arthropoda (Phylum) > Collembola (Class) > Poduromorpha (Order) > Onychiuridae (Family)
     Onychiurus Martynova, 1976 † accepted as Onychiurus Martynova, 1976 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Collembola (Class) > (Order) > Collembola (awaiting allocation) (Family)

Onychoceras
     Onychoceras Wunstorf, 1905 † · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Ammonitida (Order) > Ammonoidea (awaiting allocation) (Family)
     Onychoceras Ulrich & Foerste, 1935 accepted as Onychoceras Ulrich & Foerste, 1935 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Onychocerus
     Onychocerus Chevrolat, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Onychocerus Lepeletier & Audinet-Serville, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Onychoctenus
 Onychoctenus Agassiz, 1846 accepted as Onyctenus Lepeletier & Serville, 1828 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Meloidae (Family)
 Onychoctenus Gemminger & Harold, 1870 accepted as Onyctenus Lepeletier & Serville, 1828 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Meloidae (Family)

Onychodactylus
     Onychodactylus Tschudi, 1838 · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Caudata (Order) > Hynobiidae (Family)
     Onychodactylus Entz, 1884 accepted as Onychodactylus Entz, 1884 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)

Onychodectes
     Onychodectes Cope, 1888 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Cimolesta (Order) > Stylinodontidae (Family)
     Onychodectes Cope, 1888 † accepted as Onychodectes Cope, 1888 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Cimolesta (Order) > Stylinodontidae (Family)

Onychodes
 Onychodes Meyrick, 1890 accepted as Onycodes Guenée, 1857 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
 Onychodes Schenkling, 1928 accepted as Onichodon Newman, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Eucnemidae (Family)

Onychodon
 Onychodon Agassiz, 1845 accepted as Onichodon Newman, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Eucnemidae (Family)
 Onychodon Dybowski, 1872 accepted as Hypophthalmichthys Bleeker, 1860 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cypriniformes (Order) > Cyprinidae (Family)

Onychogale
 Onychogale Gray, 1865 accepted as Herpestes Illiger, 1811 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Herpestidae (Family)
 Onychogale Thomas, 1883 accepted as Onychogalea Gray in Grey, 1841 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Diprotodontia (Order) > Macropodidae (Family)

Onychognathus
     Onychognathus Hartlaub, 1849 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Sturnidae (Family)
 Onychognathus Troschel, 1866 accepted as Chromis Cuvier, 1814 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Pomacentridae (Family)

Onychomyia
     Onychomyia Stein, 1919 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Muscidae (Family)
     Onychomyia Frey, 1921 accepted as Onychomyia Frey, 1921 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Therevidae (Family)

Onychomysis
     Onychomysis Krøyer, 1859 accepted as Onychomysis Krøyer, 1859 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Mysida (Order) > Mysidae (Family)
 Onychomysis Czerniavsky, 1882 accepted as Mysis Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Mysida (Order) > Mysidae (Family)

Onychonema
     Onychonema Baylis, 1943 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Drilonematida (Order) > Ungellidae (Family)
     Onychonema G.C. Wallich, 1860 · Plantae (Kingdom) > Charophyta (Phylum) > Conjugatophyceae (Class) > Zygnematales (Order) > Desmidiaceae (Family)

Onychopterus
     Onychopterus Reichenbach, 1850 accepted as Onychopterus Reichenbach, 1850 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
 Onychopterus Clarke & Ruedemann, 1912 † accepted as Onychopterella Størmer, 1951 † · Animalia (Kingdom) > Arthropoda (Phylum) > Merostomata (Class) > Eurypterida (Order) > Eurypterida (awaiting allocation) (Family)

Onychopterygia
 Onychopterygia Agassiz, 1846 accepted as Onypterygia Dejean, 1831 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Onychopterygia Gemminger & Harold, 1868 accepted as Onypterygia Dejean, 1831 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Onychopus
     Onychopus Lilienstern, 1939 † accepted as Onychopus Lilienstern, 1939 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)
 Onychopus Duméril & Bibron, 1854 accepted as Onychopus Duméril & Bibron, 1854 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)
     Onychopus Fitzinger, 1843 accepted as Onychopus Fitzinger, 1843 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)

Onychospina
     Onychospina Bonaparte, 1853 accepted as Onychospina Bonaparte, 1853 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Onychospina Gray, 1855 accepted as Onychospina Gray, 1855 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Onychospiza
 Onychospiza Rey, 1872 accepted as Onychospiza Rey, 1872 (Unjustified (?) emendation) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Onychospiza Przewalski, 1876 accepted as Onychospiza Przewalski, 1876 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Onychoteuthis
     Onychoteuthis Lichtenstein, 1818 · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Teuthoidea (Order) > Onychoteuthidae (Family)
 Onychoteuthis d'Orbigny in Férussac & d'Orbigny, 1839 † accepted as Enoploteuthis d'Orbigny [in Rüppell], 1844 · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Teuthoidea (Order) > Enoploteuthidae (Family)

Onyx
     Onyx Cobb, 1891 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Desmodorida (Order) > Desmodoridae (Family)
 Onyx Gray, 1821 accepted as Oryx Blainville, 1816 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Artiodactyla (Order) > Bovidae (Family)

Onzelcentrum
     Onzelcentrum J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Onzelcentrum J.M.H. Shaw, 2004 accepted as Onzelcentrum J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Onzeloda
     Onzeloda J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Onzeloda J.M.H. Shaw, 2004 accepted as Onzeloda J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Onzelumnia
     Onzelumnia J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Onzelumnia J.M.H. Shaw, 2004 accepted as Onzelumnia J.M.H. Shaw, 2005 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Oocephala
     Oocephala Czerny, 1932 accepted as Oocephala Czerny, 1932 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Heleomyzidae (Family)
     Oocephala (S.B. Jones) H.E. Robinson, 1999 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
 Oocephala Agassiz, 1846 accepted as Cephaloon Newman, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Stenotrachelidae (Family)

Oocephalus
     Oocephalus Schneider, 1886 · Chromista (Kingdom) > Miozoa (Phylum) > Gregarinomorphea (Class) > Arthrogregarida (Order) > Stylocephalidae (Family)
     Oocephalus (Benth.) R.M. Harley & J.F.B. Pastore, 2012 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Lamiaceae (Family)

Oocystis
     Oocystis Dreyfuss, 1939 † · Animalia (Kingdom) > Echinodermata (Phylum) > Rhombifera (Class) > Rhombifera (awaiting allocation) (Order) > Rhombifera (awaiting allocation) (Family)
     Oocystis Nägeli ex A. Braun, 1855 · Plantae (Kingdom) > Chlorophyta (Phylum) > Trebouxiophyceae (Class) > Oocystales (Order) > Oocystaceae (Family)

Oodes
     Oodes Bonelli, 1810 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Oodes Samouelle, 1819 accepted as Oodes Bonelli, 1810 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Oodinus
     Oodinus Motschoulsky, 1864 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Oodinus Fairmaire, 1869 accepted as Eucamptognathus Chaudoir, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Oogaster
     Oogaster Faldermann, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)
 Oogaster Lacordaire, 1842 accepted as Brachysphaenus Lacordaire, 1842 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Erotylidae (Family)
 Oogaster Corda, 1854 accepted as Tuber F.H. Wiggers, 1780 · Fungi (Kingdom) > Ascomycota (Phylum) > Pezizomycetes (Class) > Pezizales (Order) > Tuberaceae (Family)

Oogeton
     Oogeton Kaszab, 1941 accepted as Oogeton Kaszab, 1941 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Oogeton Miwa, 1939 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Ooides
 Ooides Bode, 1953 † accepted as Ooidellus Carpenter, 1985 † · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera incertae sedis (Family)
 Ooides Agassiz, 1846 accepted as Tetraodon Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Tetraodontiformes (Order) > Tetraodontidae (Family)
 Ooides Agassiz, 1846 accepted as Ovoides Anonymous, 1798 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Tetraodontiformes (Order) > Tetraodontidae (Family)

Oolopygus
     Oolopygus Desor, 1857 † · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Cassiduloida (Order) > Cassiduloida (awaiting allocation) (Family)
     Oolopygus d'Orbigny, 1857 † · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Cassiduloida (Order) > Pliolampadidae (Family)

Oonema
 Oonema Lendenfeld, 1915 accepted as Hyalonema Gray, 1832 · Animalia (Kingdom) > Porifera (Phylum) > Hexactinellida (Class) > Amphidiscosida (Order) > Hyalonematidae (Family)
 Oonema Ijima, 1927 accepted as Hyalonema Gray, 1832 (reverted subgenus transfer) · Animalia (Kingdom) > Porifera (Phylum) > Hexactinellida (Class) > Amphidiscosida (Order) > Hyalonematidae (Family)

Oophthora
     Oophthora Kirchner, 1863 accepted as Oophthora Kirchner, 1863 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Acari (awaiting allocation) (Order) > Acari (awaiting allocation) (Family)
 Oophthora Aurivillius, 1898 accepted as Trichogramma Westwood, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Trichogrammatidae (Family)

Oopiestus
 Oopiestus Chevrolat, 1833 accepted as Oopiestus Chevrolat, 1833 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)
 Oopiestus Dejean, 1834 accepted as Oopiestus Dejean, 1834 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Oops
 Oops Germar, 1848 accepted as Oophthalmus Marshall, 1943 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Oops Agassiz, 1846 accepted as Oonops Templeton, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Oonopidae (Family)

Oosomus
     Oosomus Schoenherr, 1826 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Oosomus Schönherr, 1823 accepted as Oosomus Schoenherr, 1826 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Oosomus Motschoulsky, 1860 accepted as Pseudocleonus Chevrolat, 1873 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Oospira
     Oospira Blanford, 1872 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Clausiliidae (Family)
     Oospira Chatton & Lwoff, 1930 accepted as Oospira Chatton & Lwoff, 1930 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)

Oospora
 Oospora Sauvageau & Radais, 1892 accepted as Oospora Sauvageau & Radais, 1892 (No current standing in Prokaryotic nomenclature.) · Bacteria (Kingdom) > Actinobacteria (Phylum) > Actinobacteria (Class) > Actinomycetales (Order) > Actinomycetaceae (Family)
     Oospora Wallroth, 1833 · Fungi (Kingdom) > Ascomycota (Phylum) > Leotiomycetes (Class) > Erysiphales (Order) > Erysiphaceae (Family)

Ootheca
     Ootheca Dejean, 1835 accepted as Ootheca Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Ootheca Chapuis in Lacordaire, 1875 accepted as Ootheca Chapuis in Lacordaire, 1875 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Ootheca A.G. Nathorst, 1914 † accepted as Ootheca A.G. Nathorst, 1914 † (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Pteridospermopsida (Class) > Pteridospermopsida (awaiting allocation) (Order) > Pteridospermopsida (awaiting allocation) (Family)

Ootoma
     Ootoma Dejean, 1833 accepted as Ootoma Dejean, 1833 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Ootoma Blanchard, 1850 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Ootoma Koperberg, 1931 accepted as Buccinaria Kittl, 1887 (Invalid: junior homonym of Ootoma Dejean, 1833 and Ootoma Blanchard, 1850; Ootomella is a replacement name) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Neogastropoda (Order) > Raphitomidae (Family)

Opalia
     Opalia H. Adams & A. Adams, 1853 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Ptenoglossa (Order) > Epitoniidae (Family)
     Opalia Carpenter, 1865 accepted as Opalia Carpenter, 1865 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Ptenoglossa (Order) > Epitoniidae (Family)

Opalimosina
     Opalimosina Rohácek, 1982 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Sphaeroceridae (Family)
     Opalimosina Rohácek, 1983 accepted as Opalimosina Rohácek, 1983 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Sphaeroceridae (Family)

Opatrinus
     Opatrinus Dejean, 1821 accepted as Opatrinus Dejean, 1821 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)
     Opatrinus Guérin-Ménéville in Duperry, 1838 accepted as Opatrinus Guérin-Ménéville in Duperry, 1838 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Opegrapha
     Opegrapha E. Acharius, 1809 · Fungi (Kingdom) > Ascomycota (Phylum) > Arthoniomycetes (Class) > Arthoniales (Order) > Roccellaceae (Family)
 Opegrapha Humboldt, 1793 accepted as Graphis Adanson, 1763 · Fungi (Kingdom) > Ascomycota (Phylum) > Lecanoromycetes (Class) > Ostropales (Order) > Graphidaceae (Family)

Opercularia
     Opercularia J. Gaertner, 1788 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Rubiaceae (Family)
     Opercularia Goldfuss, 1820 · Chromista (Kingdom) > Ciliophora (Phylum) > Oligohymenophorea (Class) > Peritrichida (Order) > Operculariidae (Family)
 Opercularia J. Stirton, 1878 accepted as Phyllobathelium (J. Müller Arg.) J. Müller Arg., 1890 · Fungi (Kingdom) > Ascomycota (Phylum) > Dothideomycetes (Class) > Dothideomycetes incertae sedis (Order) > Phyllobatheliaceae (Family)

Operculella
     Operculella Monterosato, 1915 accepted as Operculella Monterosato, 1915 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Ostreida (Order) > Anomiidae (Family)
 Operculella Kheswalla, 1941 accepted as Phacidiopycnis Potebnia, 1912 · Fungi (Kingdom) > Ascomycota (Phylum) > Leotiomycetes (Class) > Leotiales (Order) > Bulgariaceae (Family)
 Operculella Reichenbach, 1828 accepted as Opercularia Goldfuss, 1820 · Chromista (Kingdom) > Ciliophora (Phylum) > Oligohymenophorea (Class) > Peritrichida (Order) > Operculariidae (Family)

Operculina
     Operculina d'Orbigny, 1826 · Chromista (Kingdom) > Retaria (Phylum) > Globothalamea (Class) > Rotaliida (Order) > Nummulitidae (Family)
     Operculina Silva Manso, 1836 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Solanales (Order) > Convolvulaceae (Family)
 Operculina Bory de St. Vincent, 1827 accepted as Opercularia Goldfuss, 1820 (junior homonym and synonym) · Chromista (Kingdom) > Ciliophora (Phylum) > Oligohymenophorea (Class) > Peritrichida (Order) > Operculariidae (Family)

Operculites
     Operculites K.R. Newman, 1965 † · Protozoa (Kingdom) > Acritarcha (Phylum) > Acritarcha (awaiting allocation) (Class) > Acritarcha (awaiting allocation) (Order) > Acritarcha (awaiting allocation) (Family)
 Operculites Gesner, 1758 † accepted as (unavailable name (suppressed work)) · Animalia (Kingdom) > Animalia (awaiting allocation) (Phylum) > Animalia (awaiting allocation) (Class) > Animalia (awaiting allocation) (Order) > Animalia (awaiting allocation) (Family)

Opharus
     Opharus Walker, 1855 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Arctiidae (Family)
 Opharus Bolívar, 1917 accepted as Opharicus Uvarov, 1940 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Acrididae (Family)

Ophelia
     Ophelia Savigny, 1822 · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Opheliida (Order) > Opheliidae (Family)
     Ophelia Robineau-Desvoidy, 1830 accepted as Ophelia Robineau-Desvoidy, 1830 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Sarcophagidae (Family)
 Ophelia D. Don ex G. Don, 1837 accepted as Swertia Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Gentianaceae (Family)

Ophelina
     Ophelina Örsted, 1843 · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Opheliida (Order) > Opheliidae (Family)
 Ophelina Griffith, 1833 accepted as Ophelia Savigny, 1822 · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Opheliida (Order) > Opheliidae (Family)

Opheltes
     Opheltes Holmgren, 1858 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Ichneumonidae (Family)
     Opheltes Thomson, 1864 accepted as Opheltes Thomson, 1864 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)

Ophiceras
     Ophiceras Griesbach, 1880 † · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Ceratitida (Order) > Ceratitida (awaiting allocation) (Family)
     Ophiceras Suess, 1865 accepted as Ophiceras Suess, 1865 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Ophiderpeton
     Ophiderpeton Etheridge, 1866 † · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Aistopoda (Order) > Ophiderpetontidae (Family)
     Ophiderpeton Fristch, 1879 † accepted as Ophiderpeton Fristch, 1879 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Amphibia (awaiting allocation) (Order) > Amphibia (awaiting allocation) (Family)

Ophidion
     Ophidion Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Ophidiiformes (Order) > Ophidiidae (Family)
     Ophidion C.A. Luer, 1982 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
     Ophidion Pomel, 1853 † accepted as Ophidion Pomel, 1853 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)

Ophieleotris
 Ophieleotris Aurich, 1938 accepted as Giuris Sauvage, 1880 (synonym) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Eleotridae (Family)
 Ophieleotris Regan, Norman & White, 1938 (ex Aurich) accepted as Giuris Sauvage, 1880 (synonym) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Eleotridae (Family)

Ophilia
 Ophilia Schiner, 1862 accepted as Ophilia Schiner, 1862 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Diptera (awaiting allocation) (Family)
 Ophilia Audouin & Milne-Edwards, 1833 accepted as Ophelia Savigny, 1822 · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Opheliida (Order) > Opheliidae (Family)

Ophiobolus
 Ophiobolus Wetzel, 1933 † accepted as · Protozoa (Kingdom) > Acritarcha (Phylum) > Acritarcha (awaiting allocation) (Class) > Acritarcha (awaiting allocation) (Order) > Acritarcha (awaiting allocation) (Family)
     Ophiobolus Riess, 1854 · Fungi (Kingdom) > Ascomycota (Phylum) > Dothideomycetes (Class) > Pleosporales (Order) > Leptosphaeriaceae (Family)

Ophiocaulon
     Ophiocaulon Rafinesque, 1838 accepted as Ophiocaulon Rafinesque, 1838 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)
 Ophiocaulon J.D. Hooker in Bentham & J.D. Hooker, 1867 accepted as Adenia Forsskål, 1775 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malpighiales (Order) > Passifloraceae (Family)

Ophiocephalus
     Ophiocephalus Wiggins, 1933 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Orobanchaceae (Family)
 Ophiocephalus Hamilton, 1822 accepted as Channa Scopoli, 1777 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Channidae (Family)
 Ophiocephalus Blainville, 1828 accepted as Lineus Sowerby, 1806 (synonym) · Animalia (Kingdom) > Nemertea (Phylum) > Anopla (Class) > Heteronemertea (Order) > Lineidae (Family)
 Ophiocephalus Bloch, 1793 accepted as Ophicephalus Bloch, 1793 (misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Channidae (Family)

Ophioceras
     Ophioceras P.A. Saccardo, 1883 · Fungi (Kingdom) > Ascomycota (Phylum) > Sordariomycetes (Class) > Sordariomycetidae incertae sedis (Order) > Magnaporthaceae (Family)
     Ophioceras Barrande, 1865 † · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Tarphycerida (Order) > Ophidioceratidae (Family)
     Ophioceras Hyatt, 1867 † accepted as Ophioceras Hyatt, 1867 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Oncocerida (Order) > Discoceratidae (Family)

Ophiochaeta
     Ophiochaeta Lütken, 1869 · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiodermatidae (Family)
 Ophiochaeta (P.A. Saccardo) P.A. Saccardo, 1895 accepted as Acanthophiobolus Berlese, 1893 · Fungi (Kingdom) > Ascomycota (Phylum) > Dothideomycetes (Class) > Pleosporales (Order) > Tubeufiaceae (Family)

Ophiocrinus
     Ophiocrinus Charlesworth, 1865 accepted as Ophiocrinus Charlesworth, 1865 (unassessed) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinodermata (awaiting allocation) (Class) > Echinodermata (awaiting allocation) (Order) > Echinodermata (awaiting allocation) (Family)
     Ophiocrinus Salter, 1856 † accepted as Ophiocrinus Salter, 1856 † (unassessed) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinodermata (awaiting allocation) (Class) > Echinodermata (awaiting allocation) (Order) > Echinodermata (awaiting allocation) (Family)
     Ophiocrinus Angelin, 1878 accepted as Ophiocrinus Angelin, 1878 (unassessed) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinodermata (awaiting allocation) (Class) > Echinodermata (awaiting allocation) (Order) > Echinodermata (awaiting allocation) (Family)
 Ophiocrinus Semper, 1868 † accepted as Eudiocrinus Carpenter, 1882 (synonym) · Animalia (Kingdom) > Echinodermata (Phylum) > Crinoidea (Class) > Comatulida (Order) > Eudiocrinidae (Family)

Ophioderma
 Ophioderma (Blume) Endlicher, 1836 accepted as Ophioglossum Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Ophioglossales (Order) > Ophioglossaceae (Family)
     Ophioderma Müller & Troschel, 1840 · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiodermatidae (Family)

Ophiodes
     Ophiodes Guenée, 1841 accepted as Ophiodes Guenée, 1841 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Ophiodes Hartig, 1847 accepted as Ophiodes Hartig, 1847 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
 Ophiodes Hincks, 1866 accepted as Hydrodendron Hincks, 1874 · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Leptothecata (Order) > Haleciidae (Family)
 Ophiodes Murray, 1877 accepted as Aponomma Neumann, 1899 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Ixodida (Order) > Ixodidae (Family)
     Ophiodes Wagler, 1830 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Diploglossidae (Family)

Ophiodesmus
     Ophiodesmus Cook, 1896 · Animalia (Kingdom) > Arthropoda (Phylum) > Diplopoda (Class) > Polydesmida (Order) > Macrosternodesmidae (Family)
 Ophiodesmus Ziesenhenne, 1940 accepted as Ophionereis Lütken, 1859 (homonym of Ophiodesmus Cook, 1896, Myriapoda) · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiochitonidae (Family)

Ophiodiscus
     Ophiodiscus Hertwig, 1882 · Animalia (Kingdom) > Cnidaria (Phylum) > Anthozoa (Class) > Actiniaria (Order) > Actinostolidae (Family)
     Ophiodiscus Yankovskii, 1976 accepted as Ophiodiscus Yankovskii, 1976 (unassessed) · Chromista (Kingdom) > Ciliophora (Phylum) > Ciliophora (awaiting allocation) (Class) > Ciliophora (awaiting allocation) (Order) > Ciliophora (awaiting allocation) (Family)

Ophioglossites
     Ophioglossites Massalongo, 1850 † accepted as Ophioglossites Massalongo, 1850 † (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malpighiales (Order) > Podostemaceae (Family)
 Ophioglossites N.A. Bolchovitina, 1959 † accepted as · Plantae (Kingdom) > Sporae dispersae (Phylum) > (Class) > (Order) > (Family)

Ophiogongylus
     Ophiogongylus Lizaso, 1983 accepted as Ophiogongylus Lizaso, 1983 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Acari (awaiting allocation) (Order) > Acari (awaiting allocation) (Family)
     Ophiogongylus Lombert & Moss, 1983 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Mesostigmata (Order) > Ixodorhynchidae (Family)

Ophioides
     Ophioides Herrmannsen, 1847 accepted as Ophioides Herrmannsen, 1847 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Ophioides Allman, 1872 accepted as Ophiodissa Stechow, 1919 · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Leptothecata (Order) > Haleciidae (Family)
 Ophioides Hincks, 1866 accepted as Ophinella Stechow, 1919 (preoccupied) · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Leptothecata (Order) > Kirchenpaueriidae (Family)

Ophiolypus
 Ophiolypus Koehler, 1897 accepted as Ophiolypus Koehler, 1897 (Misspelling) · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiuridae (Family)
 Ophiolypus Lyman, 1878 accepted as Ophiolipus Lyman, 1878 (misspelling) · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiactidae (Family)

Ophiomorpha
     Ophiomorpha Szépligeti, 1905 accepted as Ophiomorpha Szépligeti, 1905 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
     Ophiomorpha Nilsson in Mantell, 1836 accepted as Ophiomorpha Nilsson in Mantell, 1836 (unassessed) · Animalia (Kingdom) > Animalia (awaiting allocation) (Phylum) > Animalia (awaiting allocation) (Class) > Animalia (awaiting allocation) (Order) > Animalia (awaiting allocation) (Family)

Ophiomorphus
 Ophiomorphus Cope, 1862 accepted as Ophiomorphus Cope, 1862 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Colubridae (Family)
     Ophiomorphus Haas, 1980 † accepted as Ophiomorphus Haas, 1980 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Lepidosauria (awaiting allocation) (Order) > Lepidosauria (awaiting allocation) (Family)
 Ophiomorphus Lacordaire, 1854 accepted as Dolicaon Laporte, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
     Ophiomorphus Dejean, 1833 accepted as Dolicaon Laporte, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)

Ophionella
     Ophionella P.V. Bruyns, 1981 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Apocynaceae (Family)
     Ophionella Kent, 1882 accepted as Ophionella Kent, 1882 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)

Ophionema
 Ophionema Lütken, 1869 accepted as Amphiura Forbes, 1843 (rank change) · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Amphiuridae (Family)
 Ophionema Hincks, 1874 accepted as Ophinella Stechow, 1919 (preoccupied) · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Leptothecata (Order) > Kirchenpaueriidae (Family)

Ophiopeltis
 Ophiopeltis J.V. Almeida & Sousa da Câmara, 1903 accepted as Micropeltis Montagne in Ramon de la Sagra, 1838-1842 · Fungi (Kingdom) > Ascomycota (Phylum) > Dothideomycetes (Class) > Dothideomycetidae incertae sedis (Order) > Micropeltidaceae (Family)
 Ophiopeltis Düben & Koren, 1846 accepted as Amphiura Forbes, 1843 (synonym) · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Amphiuridae (Family)

Ophiophthalmus
 Ophiophthalmus Fitzinger, 1843 accepted as Lialis Gray, 1835 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Pygopodidae (Family)
 Ophiophthalmus Matsumoto, 1917 accepted as Ophiomitrella Verrill, 1899 (junior homonym) · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiacanthidae (Family)

Ophiopleura
     Ophiopleura Danielssen & Koren, 1877 · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiuridae (Family)
     Ophiopleura Duncan, 1878 · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiuridae (Family)

Ophiopsis
     Ophiopsis Agassiz, 1834 † · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Amiiformes (Order) > Macrosemiidae (Family)
 Ophiopsis Fitzinger, 1843 accepted as Lerista Bell, 1833 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Scincidae (Family)

Ophiopteris
     Ophiopteris E. A. Smith, 1877 · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiocomidae (Family)
 Ophiopteris Reinwardt, 1825 accepted as Oleandra Cavanilles, 1799 · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Polypodiales (Order) > Oleandraceae (Family)

Ophiorrhiza
     Ophiorrhiza Gloger, 1841 accepted as Ophiorrhiza Gloger, 1841 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
     Ophiorrhiza Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Rubiaceae (Family)

Ophiosema
     Ophiosema Romieux, 1943 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Nolidae (Family)
 Ophiosema Öpik, 1968 † accepted as Phasoia Hinz-Schallreuter, 1993 † (taxon accepted at subgenus level) · Animalia (Kingdom) > Arthropoda (Phylum) > Ostracoda (Class) > Bradoriida (Order) > Bradoriida (awaiting allocation) (Family)

Ophiosoma
     Ophiosoma Szidat, 1928 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Strigeidida (Order) > Strigeidae (Family)
 Ophiosoma Gray, 1840 accepted as Ophiocoma L. Agassiz, 1836 · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiocomidae (Family)
 Ophiosoma Agassiz, 1846 accepted as Ophisoma Swainson, 1839 (misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Anguilliformes (Order) > Congridae (Family)

Ophiostoma
     Ophiostoma H. Sydow & P. Sydow, 1919 · Fungi (Kingdom) > Ascomycota (Phylum) > Sordariomycetes (Class) > Ophiostomatales (Order) > Ophiostomataceae (Family)
 Ophiostoma Rudolphi, 1801 accepted as Cystidicola Fischer, 1798 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Spirurida (Order) > Cystidicolidae (Family)

Ophiostomus
 Ophiostomus Agassiz, 1846 accepted as Ophiostomus Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Ophiostomus Mudie in Blyth, 1840 accepted as Cystidicola Fischer, 1798 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Spirurida (Order) > Cystidicolidae (Family)

Ophiothamnus
     Ophiothamnus Koehler, 1906 · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiacanthidae (Family)
     Ophiothamnus Lyman, 1869 · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiacanthidae (Family)

Ophiothrix
     Ophiothrix Müller & Troschel, 1840 · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiotrichidae (Family)
     Ophiothrix Corda, 1835 accepted as Ophiothrix Corda, 1835 · Bacteria (Kingdom) > Cyanobacteria (Phylum) > Cyanophyceae (Class) > Cyanophyceae (awaiting allocation) (Order) > Cyanophyceae incertae sedis (Family)
     Ophiothrix Nägeli, 1849 · Chromista (Kingdom) > Ochrophyta (Phylum) > Xanthophyceae (Class) > Mischococcales (Order) > Ophiocytiaceae (Family)
     Ophiothrix C.L. Sant'Anna, T.M.P. Azevedo, J. Kaštovský & J. Komárek, 2010 · Bacteria (Kingdom) > Cyanobacteria (Phylum) > Cyanophyceae (Class) > Nostocales (Order) > Scytonemataceae (Family)

Ophiotoma
     Ophiotoma Lyman, 1883 · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiacanthidae (Family)
     Ophiotoma Verrill, 1899 · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiacanthidae (Family)

Ophira
 Ophira Rondani, 1856 accepted as Ophyra Robineau-Desvoidy, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Muscidae (Family)
 Ophira J. Burman ex Linnaeus, 1771 accepted as Grubbia P.J. Bergius, 1767 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Cornales (Order) > Grubbiaceae (Family)

Ophirion
     Ophirion Townsend, 1911 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Tachinidae (Family)
 Ophirion Por, 1967 accepted as Pordfus Özdikmen, 2008 (junior homonym) · Animalia (Kingdom) > Arthropoda (Phylum) > Maxillopoda (Class) > Harpacticoida (Order) > Canthocamptidae (Family)

Ophis
 Ophis Gray, 1840 † accepted as Ophis Gray, 1840 † (Misspelling) · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Astartidae (Family)
 Ophis Turton, 1807 accepted as Ophichthus Ahl, 1789 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Anguilliformes (Order) > Ophichthidae (Family)
     Ophis Dejean, 1821 accepted as Cleonis Dejean, 1821 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Ophis Wagler in Spix, 1824 accepted as Waglerophis de Lemos Romano & Hoge, 1972 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Colubridae (Family)

Ophisaurus
     Ophisaurus Valenciennes in d'Orbigny, 1847 accepted as Ophisaurus Valenciennes in d'Orbigny, 1847 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Pisces (awaiting allocation) (Class) > Pisces (awaiting allocation) (Order) > Pisces (awaiting allocation) (Family)
     Ophisaurus Daudin, 1803 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Anguidae (Family)

Ophisma
 Ophisma Delage & Hérouard, 1903 † accepted as Ophisma Delage & Hérouard, 1903 † (Misspelling) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinodermata (awaiting allocation) (Class) > Echinodermata (awaiting allocation) (Order) > Echinodermata (awaiting allocation) (Family)
     Ophisma Guenée, 1852 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)

Ophistoma
 Ophistoma Luther, 1905 accepted as Opistomum Schmidt, 1848 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Turbellaria (Class) > Neorhabdocoela (Order) > Typhloplanidae (Family)
 Ophistoma Rudolphi, 1809 accepted as Cucullanus Müller, 1777 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Spirurida (Order) > Cucullanidae (Family)

Ophistomis
     Ophistomis Dejean, 1835 accepted as Ophistomis Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Ophistomis Thomson, 1857 accepted as Strangalia Audinet-Serville, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Ophites
     Ophites Wagler, 1830 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Colubridae (Family)
 Ophites Erichson, 1839 accepted as Opithes Blackwelder, 1952 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)

Ophitis
 Ophitis Zoological Record accepted as Oplitis Berlese, 1884 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Mesostigmata (Order) > Oplitidae (Family)
     Ophitis Felder, 1874 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Notodontidae (Family)
 Ophitis accepted as Ophites Wagler, 1830 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Colubridae (Family)

Ophiuraster
     Ophiuraster H.L. Clark, 1939 · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiuridae (Family)
 Ophiuraster Miller, 1958 † accepted as Archaeophiomusium Hattin, 1967 † (Homonym of Ophiuraster H.L. Clark, 1939) · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiurida (Order) > Ophiurida (awaiting allocation) (Family)

Ophiurella
     Ophiurella Stürtz, 1886 accepted as Ophiurella Stürtz, 1886 (unassessed) · Animalia (Kingdom) > Echinodermata (Phylum) > Asterozoa (awaiting allocation) (Class) > Asterozoa (awaiting allocation) (Order) > Asterozoa (awaiting allocation) (Family)
     Ophiurella Agassiz, 1836 † · Animalia (Kingdom) > Echinodermata (Phylum) > Ophiuroidea (Class) > Ophiuroidea (awaiting allocation) (Order) > Ophiuroidea (awaiting allocation) (Family)

Ophiurus
     Ophiurus Link, 1807 accepted as Ophiurus Link, 1807 (unassessed) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinodermata (awaiting allocation) (Class) > Echinodermata (awaiting allocation) (Order) > Echinodermata (awaiting allocation) (Family)
 Ophiurus Agassiz, 1846 accepted as Ophisurus Lacepède, 1800 (misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Anguilliformes (Order) > Ophichthidae (Family)

Ophonus
     Ophonus Dejean, 1821 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Ophonus Stephens, 1827 accepted as Ophonus Dejean, 1821 (later usage) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Ophrias
     Ophrias Rafinesque, 1815 accepted as Ophrias Rafinesque, 1815 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)
 Ophrias Cuvier, 1829 accepted as Acanthophis Daudin in Sonnini, 1803 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Elapidae (Family)

Ophryastes
     Ophryastes Schönherr, 1833 accepted as Ophryastes Schönherr, 1833 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Ophryastes Say, 1831 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Ophryastes Germar, 1829 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Ophrydium
     Ophrydium Bory de St. Vincent, 1826 · Chromista (Kingdom) > Ciliophora (Phylum) > Oligohymenophorea (Class) > Peritrichida (Order) > Ophrydiidae (Family)
 Ophrydium Ehrenberg, 1830 accepted as Ophrydium Ehrenberg, 1830 (Misspelling) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)

Ophrygonius
     Ophrygonius Zang, 1904 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Passalidae (Family)
 Ophrygonius Boucher accepted as Basilianus Kaup, 1871 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Passalidae (Family)

Ophryocotylus
     Ophryocotylus Srivastava & Capoor, 1977 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Cestoda (Class) > Cyclophyllidea (Order) > Davaineidae (Family)
 Ophryocotylus Srivastav & Capoor, 1982 accepted as Ophryocotylus Srivastava & Capoor, 1977 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Cestoda (Class) > Cyclophyllidea (Order) > Davaineidae (Family)

Ophthalmidium
     Ophthalmidium Kubler & Zwingli, 1870 · Chromista (Kingdom) > Retaria (Phylum) > Tubothalamea (Class) > Miliolida (Order) > Ophthalmidiidae (Family)
 Ophthalmidium accepted as Ophthalmidion Duméril & Bibron, 1844 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Typhlopidae (Family)
 Ophthalmidium Eschweiler, 1824 accepted as Pertusaria A.P. de Candolle in Lamarck & A.P. de Candolle, 1805 · Fungi (Kingdom) > Ascomycota (Phylum) > Lecanoromycetes (Class) > Pertusariales (Order) > Pertusariaceae (Family)

Ophthalmocoris
     Ophthalmocoris Bode, 1953 † accepted as Ophthalmocoris Bode, 1953 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
 Ophthalmocoris Berg, 1883 accepted as Ophthalmocoris Berg, 1883 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Capsidae (Family)
     Ophthalmocoris Zetterstedt, 1838 accepted as Ophthalmocoris Zetterstedt, 1838 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Capsidae (Family)
 Ophthalmocoris Montandon, 1907 accepted as Germalus Stål, 1862 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Geocoridae (Family)

Ophthalmodes
     Ophthalmodes Fischer, 1834 accepted as Ophthalmodes Fischer, 1834 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Orthoptera (awaiting allocation) (Family)
 Ophthalmodes Guenée, 1857 accepted as Ophthalmitis Fletcher, 1979 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)

Ophthalmothrips
     Ophthalmothrips Hood, 1919 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Thysanoptera (Order) > Phlaeothripidae (Family)
 Ophthalmothrips Karny, 1920 accepted as Macrophthalmothrips Karny, 1922 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Thysanoptera (Order) > Phlaeothripidae (Family)

Opifex
     Opifex Hutton, 1902 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Culicidae (Family)
     Opifex Friedmann, 1927 accepted as Opifex Friedmann, 1927 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Sylviidae (Family)

Opikella
     Opikella Amsden, 1968 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Strophomenata (Class) > Strophomenatida (Order) > Leptestiidae (Family)
     Opikella Thorslund, 1940 † accepted as Opikella Thorslund, 1940 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Crustacea (awaiting allocation) (Class) > Crustacea (awaiting allocation) (Order) > Crustacea (awaiting allocation) (Family)
 Opikella Runnegar & Pojeta, 1974 † accepted as Oepikila Runnegar & Pojeta, 1974 † · Animalia (Kingdom) > Mollusca (Phylum) > Rostroconchia (Class) > Ribeirioida (Order) > Ribeiriidae (Family)

Opilio
     Opilio Herbst, 1798 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Opiliones (Order) > Phalangiidae (Family)
 Opilio accepted as Opilo Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cleridae (Family)

Opipeuter
     Opipeuter Fortey, 1974 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Proetida (Order) > Telephinidae (Family)
     Opipeuter Uzzell, 1969 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Gymnophthalmidae (Family)

Opis
     Opis Defrance, 1825 † · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Astartidae (Family)
     Opis Defrance, 1824 † accepted as Opis Defrance, 1824 † · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Astartidae (Family)
 Opis Krøyer, 1842 accepted as Opisa Boeck, 1876 (homonym) · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Amphipoda (Order) > Opisidae (Family)

Opisthocentrus
     Opisthocentrus Kner, 1868 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Stichaeidae (Family)
 Opisthocentrus Pocock, 1893 accepted as Opisthacanthus Peters, 1861 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Scorpiones (Order) > Liochelidae (Family)

Opisthocomacarus
     Opisthocomacarus Dubinin, 1955 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Astigmata (Order) > Pterolichidae (Family)
     Opisthocomacarus Dubinin, 1953 accepted as Opisthocomacarus Dubinin, 1955 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Astigmata (Order) > Pterolichidae (Family)

Opisthodon
     Opisthodon Canestrini, 1897 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Ixodida (Order) > Ixodidae (Family)
     Opisthodon Stein, 1859 · Chromista (Kingdom) > Ciliophora (Phylum) > Litostomatea (Class) > Pleurostomatida (Order) > Amphileptidae (Family)
 Opisthodon Steindachner, 1867 accepted as Limnodynastes Fitzinger, 1843 · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Anura (Order) > Limnodynastidae (Family)

Opisthodrilus
 Opisthodrilus Michaelsen in Kükenthal & Krumbach, 1928 accepted as Opisthodrilus Michaelsen in Kükenthal & Krumbach, 1928 (Misspelling) · Animalia (Kingdom) > Annelida (Phylum) > Oligochaeta (Class) > Oligochaeta (awaiting allocation) (Order) > Oligochaeta (awaiting allocation) (Family)
     Opisthodrilus Rosa, 1895 · Animalia (Kingdom) > Annelida (Phylum) > Oligochaeta (Class) > Haplotaxida (Order) > Glossoscolecidae (Family)

Opistholoba
     Opistholoba Mik, 1891 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Mycetophilidae (Family)
     Opistholoba Hussey, 1926 † accepted as Opistholoba Hussey, 1926 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Opisthometra
     Opisthometra Saakova, 1952 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Echinostomida (Order) > Saakotrematidae (Family)
     Opisthometra Poche, 1926 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Opisthorchiida (Order) > Heterophyidae (Family)

Opisthoncana
     Opisthoncana L. Koch, 1880 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Salticidae (Family)
     Opisthoncana Strand, 1913 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Salticidae (Family)

Opisthonema
     Opisthonema Gill, 1861 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Clupeiformes (Order) > Clupeidae (Family)
     Opisthonema Yu, 1974 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Gastropoda incertae sedis (Order) > Opisthonematidae (Family)

Opisthophthalmus
 Opisthophthalmus Agassiz, 1846 accepted as Opistophthalmus Koch, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Scorpiones (Order) > Scorpionidae (Family)
 Opisthophthalmus Thorell, 1876 accepted as Opistophthalmus Koch, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Scorpiones (Order) > Scorpionidae (Family)

Opisthoporus
     Opisthoporus Pfeiffer, 1851 accepted as Opisthoporus Pfeiffer, 1851 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Architaenioglossa (Order) > Cyclophoridae (Family)
 Opisthoporus Manter, 1947 accepted as Postporus Manter, 1949 (Synonym of Postporus) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Plagiorchiida (Order) > Apocreadiidae (Family)
 Opisthoporus Minot, 1877 accepted as Leptoplana Ehrenberg, 1831 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Turbellaria (Class) > Polycladida (Order) > Leptoplanidae (Family)
 Opisthoporus Fukui, 1929 accepted as Teloporia Fukui, 1933 (Pre-occupied) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Echinostomida (Order) > Pronocephalidae (Family)

Opisthopus
     Opisthopus Rathbun, 1893 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Pinnotheridae (Family)
     Opisthopus Heyler & Lessertisseur, 1963 † accepted as Opisthopus Heyler & Lessertisseur, 1963 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)

Opisthorhinus
     Opisthorhinus Bravard, 1857 † accepted as Opisthorhinus Bravard, 1857 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
     Opisthorhinus Bravard in Burmeister, 1864 † accepted as Opisthorhinus Bravard in Burmeister, 1864 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)

Opisthostenus
     Opisthostenus Förster, 1868 accepted as Opisthostenus Förster, 1868 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
 Opisthostenus Lethierry & Severin, 1894 accepted as Opistostenus Reuter, 1882 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Pachygronthidae (Family)

Opisthostomum
 Opisthostomum Ghosh, 1928 accepted as Opisthostomatella Corliss, 1960 · Chromista (Kingdom) > Ciliophora (Phylum) > Litostomatea (Class) > Trichostomatida (Order) > Coelosomididae (Family)
 Opisthostomum Schmarda, 1859 accepted as Opistomum Schmidt, 1848 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Turbellaria (Class) > Neorhabdocoela (Order) > Typhloplanidae (Family)

Opisthothylax
     Opisthothylax Perret, 1966 · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Anura (Order) > Hyperoliidae (Family)
     Opisthothylax Perret, 1961 accepted as Opisthothylax Perret, 1961 · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Anura (Order) > Hyperoliidae (Family)

Opisthotropis
     Opisthotropis Günther, 1872 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Colubridae (Family)
 Opisthotropis Hoffmann & Tempère, 1954 accepted as Ormiscus Waterhouse, 1845 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Anthribidae (Family)

Oplocheirus
     Oplocheirus Lacordaire, 1859 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)
     Oplocheirus Dejean, 1834 accepted as Oplocheirus Lacordaire, 1859 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Oplocnemis
 Oplocnemis Fairmaire, 1849 accepted as Acicnemis Fairmaire, 1849 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Oplocnemis Dejean, 1835 accepted as Acicnemis Fairmaire, 1849 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Oplognathus
     Oplognathus Macleay, 1819 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Oplognathus Desmarest in Chenu, 1851-22 accepted as Pseudozaena Laporte, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Oplomerus
     Oplomerus Dejean, 1834 accepted as Oplomerus Dejean, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
 Oplomerus Westwood, 1840 accepted as Odynerus Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Vespidae (Family)

Oplophora
 Oplophora H. Sydow, 1921 accepted as Nyssopsora J.C. Arthur, 1906 · Fungi (Kingdom) > Basidiomycota (Phylum) > Pucciniomycetes (Class) > Pucciniales (Order) > Raveneliaceae (Family)
 Oplophora Hope, 1839 accepted as Anoplophora Hope, 1839 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Oplopus
 Oplopus Laporte, 1832 accepted as Oplopus Laporte, 1832 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Oplopus Wesmael, 1836 accepted as Odynerus Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Vespidae (Family)

Oplurus
     Oplurus Duméril & Bibron, 1837 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Opluridae (Family)
     Oplurus Cuvier, 1829 accepted as Oplurus Cuvier, 1829 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Opluridae (Family)

Opogona
     Opogona Zeller, 1853 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Tineidae (Family)
     Opogona Amsel, 1970 accepted as Opogona Amsel, 1970 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)

Oporinia
     Oporinia Hübner, 1825 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
     Oporinia D. Don, 1829 accepted as Oporinia D. Don, 1829 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)

Oppenheimiella
     Oppenheimiella Meunier, 1893 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Platypezidae (Family)
     Oppenheimiella Pfeffer, 1929 † accepted as Oppenheimiella Pfeffer, 1929 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Oppia
     Oppia C.L. Koch, 1836 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Oribatida (Order) > Oppiidae (Family)
     Oppia Robineau-Desvoidy, 1863 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Sarcophagidae (Family)

Ops
 Ops Carrington, 1865 accepted as Owenia delle Chiaje, 1844 (subjective synonym) · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Oweniida (Order) > Oweniidae (Family)
     Ops Gistl, 1847 accepted as Ops Gistl, 1847 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Crustacea (awaiting allocation) (Class) > Crustacea (awaiting allocation) (Order) > Crustacea (awaiting allocation) (Family)
     Ops Nicéville, 1895 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lycaenidae (Family)
 Ops Becker, 1910 accepted as Homops Speiser, 1923 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Chloropidae (Family)

Opsarius
     Opsarius McClelland, 1838 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cypriniformes (Order) > Cyprinidae (Family)
 Opsarius Kner, 1865 accepted as Ochetobius Günther, 1868 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cypriniformes (Order) > Cyprinidae (Family)

Opseobaris
     Opseobaris Bondar, 1942 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Opseobaris Hustache, 1951 accepted as Opseobaris Bondar, 1942 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Opsigonus
 Opsigonus Baudi, 1877 accepted as Neogonus Hampe, 1873 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Melandryidae (Family)
     Opsigonus Bassani, 1882 accepted as Opsigonus Bassani, 1882 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Pisces (awaiting allocation) (Class) > Pisces (awaiting allocation) (Order) > Pisces (awaiting allocation) (Family)
 Opsigonus Emeljanov, 2006 accepted as Orgerius Stål, 1859 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Dictyopharidae (Family)

Opsimus
     Opsimus Eschscholtz in Mannerheim, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Opsimus Thomson, 1860 accepted as Opsimus Eschscholtz in Mannerheim, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Opsimus Dejean, 1835 accepted as Opsimus Eschscholtz in Mannerheim, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Optis
 Optis Grouvelle, 1911 accepted as Trachypholis Erichson, 1845 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Zopheridae (Family)
 Optis Pascoe, 1885 accepted as Trachypholis Erichson, 1845 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Zopheridae (Family)

Opuntia
     Opuntia (Linnaeus) P. Miller, 1754 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Caryophyllales (Order) > Cactaceae (Family)
 Opuntia F. Naccari, 1828 accepted as · Plantae (Kingdom) > Chlorophyta (Phylum) > Ulvophyceae (Class) > Bryopsidales (Order) > Udoteaceae (Family)

Opuntiella
     Opuntiella L. Léger & M. Gauthier, 1932 · Fungi (Kingdom) > Zygomycota (Phylum) > Kickxellomycetes (Class) > Harpellales (Order) > Harpellales incertae sedis (Family)
     Opuntiella Kylin, 1925 · Plantae (Kingdom) > Rhodophyta (Phylum) > Florideophyceae (Class) > Gigartinales (Order) > Furcellariaceae (Family)

Oracanthus
     Oracanthus Agassiz, 1837 † · Animalia (Kingdom) > Chordata (Phylum) > Acanthodii (Class) > Climatiiformes (Order) > Gyracanthidae (Family)
 Oracanthus Ameghino, 1885 † accepted as Megatherium Cuvier, 1796 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Pilosa (Order) > Megatheriidae (Family)

Oracella
     Oracella Ferris, 1950 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Pseudococcidae (Family)
 Oracella accepted as Orcaella Gray, 1866 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Cetacea (Order) > Delphinidae (Family)

Orania
     Orania Pallary, 1900 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Neogastropoda (Order) > Muricidae (Family)
     Orania Zippelius, 1829 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Arecales (Order) > Arecaceae (Family)

Oraniella
     Oraniella Reuter, 1894 accepted as Oraniella Reuter, 1894 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Capsidae (Family)
 Oraniella Spegazzini, 1909 accepted as Massarina P.A. Saccardo, 1883 · Fungi (Kingdom) > Ascomycota (Phylum) > Dothideomycetes (Class) > Pleosporales (Order) > Massarinaceae (Family)

Orbella
     Orbella Maldonado-Capriles, 1987 accepted as Orbella Maldonado-Capriles, 1987 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Reduviidae (Family)
     Orbella V.S. Maljavkina, 1949 † accepted as Orbella V.S. Maljavkina, 1949 † (unassessed) · Plantae (Kingdom) > Sporae dispersae (Phylum) > (Class) > (Order) > (Family)

Orbicella
     Orbicella d'Orbigny, 1847 accepted as Orbicella d'Orbigny, 1847 (unassessed) · Animalia (Kingdom) > Brachiopoda (Phylum) > Lingulata (Class) > Linguliporida (Order) > Discinidae (Family)
     Orbicella Dana, 1846 · Animalia (Kingdom) > Cnidaria (Phylum) > Anthozoa (Class) > Scleractinia (Order) > Merulinidae (Family)

Orbicula
     Orbicula Sowerby, 1822 accepted as Orbicula Sowerby, 1822 (unassessed) · Animalia (Kingdom) > Brachiopoda (Phylum) > Brachiopoda (awaiting allocation) (Class) > Brachiopoda (awaiting allocation) (Order) > Brachiopoda (awaiting allocation) (Family)
     Orbicula M.C. Cooke, 1871 · Fungi (Kingdom) > Ascomycota (Phylum) > Pezizomycetes (Class) > Pezizales (Order) > Pyronemataceae (Family)
     Orbicula Defrance, 1825 accepted as Orbicula Defrance, 1825 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)
 Orbicula Reeve, 1842 accepted as Orbicula Reeve, 1842 (Misspelling) · Chromista (Kingdom) > Retaria (Phylum) > Tubothalamea (Class) > Miliolida (Order) > Peneroplidae (Family)
 Orbicula Cuvier, 1798 accepted as Crania Retzius, 1781 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Craniata (Class) > Craniidida (Order) > Craniidae (Family)

Orbicularia
     Orbicularia Deshayes, 1850 · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Pharidae (Family)
 Orbicularia V.S. Maljavkina, 1949 † accepted as · Plantae (Kingdom) > Sporae dispersae (Phylum) > (Class) > (Order) > (Family)
 Orbicularia Baillon, 1858 accepted as Phyllanthus Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malpighiales (Order) > Phyllanthaceae (Family)

Orbiculina
     Orbiculina Reeve, 1842 accepted as Orbiculina Reeve, 1842 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)
 Orbiculina Lamarck, 1816 accepted as Archaias de Montfort, 1808 (Opinion of Loeblich & Tappan, 1987) · Chromista (Kingdom) > Retaria (Phylum) > Tubothalamea (Class) > Miliolida (Order) > Soritidae (Family)

Orbiculus
     Orbiculus Bagdasaryan, 1980 † accepted as Orbiculus Bagdasaryan, 1980 † (unassessed) · Protozoa (Kingdom) > Acritarcha (Phylum) > Acritarcha (awaiting allocation) (Class) > Acritarcha (awaiting allocation) (Order) > Acritarcha (awaiting allocation) (Family)
 Orbiculus Megerle von Mühlfeld, 1811 accepted as Dosinia Scopoli, 1777 · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Veneridae (Family)

Orbignya
     Orbignya Fischer, 1887 † · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Hippuritida (Order) > Hippuritidae (Family)
 Orbignya Bertero, 1829 accepted as Orbignya Bertero, 1829 (nomen rejiciendum) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Sapindales (Order) > Sapindaceae (Family)
 Orbignya C.F.P. Martius ex Endlicher, 1837 accepted as Attalea Kunth in Humboldt, Bonpland & Kunth, 1816 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Arecales (Order) > Arecaceae (Family)
     Orbignya von Hagenow, 1842 † · Chromista (Kingdom) > Retaria (Phylum) > Globothalamea (Class) > Lituolida (Order) > Ataxophragmiidae (Family)

Orbignyella
     Orbignyella Ulrich & Bassler, 1904 † · Animalia (Kingdom) > Bryozoa (Phylum) > Stenolaemata (Class) > Trepostomatida (Order) > Trepostomata (awaiting allocation) (Family)
     Orbignyella Saidova, 1975 accepted as Orbignyella Saidova, 1975 (unassessed) · Protozoa (Kingdom) > (Phylum) > (Class) > Sarcomastigota (awaiting allocation) (Order) > Sarcomastigota (awaiting allocation) (Family)

Orbignyiceras
     Orbignyiceras Gérard & Contaut, 1936 † accepted as Orbignyiceras Gérard & Contaut, 1936 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Orbignyiceras Royo y Gomez, 1945 † accepted as Veleziceras Wright, 1957 † · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Ammonitida (Order) > Ammonoidea (awaiting allocation) (Family)

Orbiliopsis
     Orbiliopsis Velenovský, 1934 · Fungi (Kingdom) > Ascomycota (Phylum) > Leotiomycetes (Class) > Helotiales (Order) > Helotiales incertae sedis (Family)
     Orbiliopsis (Saccardo) Sydow, 1924 · Fungi (Kingdom) > Ascomycota (Phylum) > Leotiomycetes (Class) > Helotiales (Order) > Helotiales incertae sedis (Family)
 Orbiliopsis F. von Höhnel in Weese, 1926 accepted as Parorbiliopsis B.M. Spooner & R.W.G. Dennis, 1986 · Fungi (Kingdom) > Ascomycota (Phylum) > Leotiomycetes (Class) > Helotiales (Order) > Helotiaceae (Family)

Orbis
 Orbis Müller, 1766 accepted as Orbis Müller, 1766 (Published in a rejected work (ICZN)) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Tetraodontiformes (Order) > Tetraodontidae (Family)
     Orbis Schröter, 1776 accepted as Orbis Schröter, 1776 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Orbis Lea, 1833 † accepted as Orbis Lea, 1833 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Orbis Catesby, 1771 accepted as Orbis Catesby, 1771 (Published in a rejected work (ICZN)) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Tetraodontiformes (Order) > Tetraodontidae (Family)
 Orbis Blainville, 1825 accepted as Acanthocardia J.E. Gray, 1851 (not available: not used as a valid name; and also invalid: junior homonym of Orbis Müller, 1767) · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Cardiidae (Family)
 Orbis Fischer, 1813 accepted as Tetraodon Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Tetraodontiformes (Order) > Tetraodontidae (Family)

Orbitella
     Orbitella Ma, 1938 accepted as Orbitella Ma, 1938 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
     Orbitella Douvillé, 1915 accepted as Orbitella Douvillé, 1915 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)

Orbitina
     Orbitina Risso, 1826 accepted as Orbitina Risso, 1826 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Orbitina Sellier de Civrieux, 1977 · Chromista (Kingdom) > Retaria (Phylum) > Globothalamea (Class) > Rotaliida (Order) > Discorbidae (Family)

Orbitremites
     Orbitremites Austin, 1842 † · Animalia (Kingdom) > Echinodermata (Phylum) > Blastoidea (Class) > Spiraculata (Order) > Spiraculata (awaiting allocation) (Family)
     Orbitremites Gray, 1840 † accepted as Orbitremites Austin, 1842 † · Animalia (Kingdom) > Echinodermata (Phylum) > Blastoidea (Class) > Spiraculata (Order) > Spiraculata (awaiting allocation) (Family)

Orbitulites
     Orbitulites Eichwald, 1829 accepted as Orbitulites Eichwald, 1829 (unassessed) · Animalia (Kingdom) > Bryozoa (Phylum) > Bryozoa (awaiting allocation) (Class) > Bryozoa (awaiting allocation) (Order) > Bryozoa (awaiting allocation) (Family)
     Orbitulites Bronn in Bronn & Roemer, 1854 accepted as Orbitulites Bronn in Bronn & Roemer, 1854 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)
 Orbitulites Griffith & Pidgeon, 1834 accepted as Orbitulites Griffith & Pidgeon, 1834 (Misspelling) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Orbitulites Berthold in Latreille, 1827 accepted as Orbitulites Berthold in Latreille, 1827 (Misspelling) · Animalia (Kingdom) > Bryozoa (Phylum) > Bryozoa (awaiting allocation) (Class) > Bryozoa (awaiting allocation) (Order) > Bryozoa (awaiting allocation) (Family)

Orbulinoides
     Orbulinoides Cordey, 1968 † · Chromista (Kingdom) > Retaria (Phylum) > Foraminifera incertae sedis (Class) > Foraminifera (awaiting allocation) (Order) > Foraminifera (awaiting allocation) (Family)
     Orbulinoides Blow & Saito, 1968 † accepted as Orbulinoides Blow & Saito, 1968 † (unassessed) · Protozoa (Kingdom) > (Phylum) > (Class) > (Order) > Protozoa (awaiting allocation) (Family)
 Orbulinoides Proto-Decima & Bolli, 1970 † accepted as Orbulinoides Cordey, 1968 † · Chromista (Kingdom) > Retaria (Phylum) > Foraminifera incertae sedis (Class) > Foraminifera (awaiting allocation) (Order) > Foraminifera (awaiting allocation) (Family)
 Orbulinoides Saidova, 1970 accepted as Orbulinelloides Saidova, 1975 · Chromista (Kingdom) > Retaria (Phylum) > Globothalamea (Class) > Globigerinida (Order) > Globigerinidae (Family)

Orbulites
     Orbulites Berthold in Latreille, 1827 accepted as Orbulites Berthold in Latreille, 1827 (unassessed) · Animalia (Kingdom) > Bryozoa (Phylum) > Bryozoa (awaiting allocation) (Class) > Bryozoa (awaiting allocation) (Order) > Bryozoa (awaiting allocation) (Family)
     Orbulites Lamarck, 1801 accepted as Orbulites Lamarck, 1801 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Orbulites Lamarck, 1816 · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)

Orca
     Orca Wagler, 1830 accepted as Orca Wagler, 1830 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Cetacea (Order) > Physeteridae (Family)
 Orca Gray, 1846 accepted as Orcinus Fitzinger, 1860 (preoccupied) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Cetacea (Order) > Delphinidae (Family)

Orcadia
     Orcadia G.K. Sutherland, 1915 · Fungi (Kingdom) > Ascomycota (Phylum) > Ascomycota incertae sedis (Class) > Ascomycota incertae sedis (Order) > Ascomycota incertae sedis (Family)
     Orcadia Boltovskoy & Watanabe, 1982 · Chromista (Kingdom) > Retaria (Phylum) > Globothalamea (Class) > Globigerinida (Order) > Hastigerinidae (Family)

Orcella
 Orcella Anderson, 1871 accepted as Orcaella Gray, 1866 (synonym) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Cetacea (Order) > Delphinidae (Family)
 Orcella Jordan & Evermann, 1896 accepted as Notropis Rafinesque, 1818 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cypriniformes (Order) > Cyprinidae (Family)
 Orcella O. Kuntze ex Earle, 1909 accepted as Clitopilus (E.M. Fries ex Rabenhorst) Kummer, 1871 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Agaricales (Order) > Entolomataceae (Family)

Orchamus
     Orchamus Stål, 1876 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Pamphagidae (Family)
     Orchamus Bolivar, 1906 accepted as Orchamus Bolivar, 1906 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tettigoniidae (Family)
 Orchamus Quaintance & Baker, 1917 accepted as Orchamoplatus Russell, 1958 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Aleyrodidae (Family)

Orchestes
     Orchestes Illiger in Kugelann, 1798 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Orchestes Tschudi, 1838 accepted as Philautus Gistl, 1848 · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Anura (Order) > Rhacophoridae (Family)
 Orchestes Leach, 1814 accepted as Orchestia Leach, 1814 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Amphipoda (Order) > Talitridae (Family)

Orchesticus
     Orchesticus Saussure, 1859 accepted as Orchesticus Saussure, 1859 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tettigoniidae (Family)
     Orchesticus Cabanis in Cabanis & Heine, 1851 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Fringillidae (Family)

Orchestris
 Orchestris Crotch, 1873 accepted as Phyllotreta Blanchard, 1845 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
 Orchestris Kirby in Richardson, 1837 accepted as Phyllotreta Chevrolat, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Orchiastrum
 Orchiastrum Lemaire, 1855 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Liliales (Order) > Liliaceae (Family)
 Orchiastrum Seguier, 1754 accepted as Spiranthes L.C. Richard, 1817 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Orchidium
 Orchidium O. Swartz in J.W. Palmstruch, 1816 accepted as Calypso R.A. Salisbury, 1807 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Orchidium Gray, 1821 accepted as Onchidium Buchannan, 1800 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Systellommatophora (Order) > Onchidiidae (Family)

Orchilus
     Orchilus Morris, 1837 accepted as Orchilus Morris, 1837 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Orchilus Tschudi, 1846 accepted as Orchilus Tschudi, 1846 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Orchiomys
     Orchiomys Ameghino, 1897 † accepted as Orchiomys Ameghino, 1897 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
     Orchiomys Ameghino, 1897 † accepted as Orchiomys Ameghino, 1897 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)

Orchipedum
     Orchipedum Braun, 1901 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Echinostomida (Order) > Orchipedidae (Family)
     Orchipedum Breda, 1829 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Orcula
     Orcula Held, 1837 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Orculidae (Family)
 Orcula Troschel, 1846 accepted as Ekmania Hansen & McKenzie, 1991 · Animalia (Kingdom) > Echinodermata (Phylum) > Holothuroidea (Class) > Dendrochirotida (Order) > Cucumariidae (Family)
 Orcula Jordan & Evermann, 1900 accepted as Notropis Rafinesque, 1818 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cypriniformes (Order) > Cyprinidae (Family)
     Orcula J.F. Weisse, 1846 accepted as Orcula J.F. Weisse, 1846 (unassessed) · Protozoa (Kingdom) > Euglenozoa (Phylum) > Euglenophyceae (Class) > Euglenida (Order) > Euglenidae (Family)

Orcus
     Orcus Mulsant, 1850 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coccinellidae (Family)
 Orcus Needham, 1897 accepted as Arigomphus Needham, 1897 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Odonata (Order) > Gomphidae (Family)
     Orcus Gailite, 1966 † · Animalia (Kingdom) > Arthropoda (Phylum) > Ostracoda (Class) > Palaeocopida (Order) > Palaeocopida (awaiting allocation) (Family)
 Orcus Uljanin, 1870 accepted as Trigonostomum Schmidt, 1852 (nomen oblitum) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Turbellaria (Class) > Neorhabdocoela (Order) > Trigonostomidae (Family)

Orcya
     Orcya Johnson, 1990 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lycaenidae (Family)
     Orcya Vellozo, 1829 accepted as Orcya Vellozo, 1829 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)

Orcynopsis
     Orcynopsis Carus, 1889-1893 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Scombridae (Family)
     Orcynopsis Gill, 1862 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Scombridae (Family)

Orcynus
 Orcynus Cuvier, 1816 accepted as Thunnus South, 1845 (synonym) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Scombridae (Family)
 Orcynus Rafinesque, 1815 accepted as Scomberoides Lacepède, 1801 (synonym) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Carangidae (Family)

Ordosia
     Ordosia Qi, 1988 † accepted as Ordosia Qi, 1988 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Ostracoda (Class) > Ostracoda (awaiting allocation) (Order) > Ostracoda (awaiting allocation) (Family)
     Ordosia Hou Lianhai, 1979 † accepted as Ordosia Hou Lianhai, 1979 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Synapsida (awaiting allocation) (Order) > Synapsida (awaiting allocation) (Family)
     Ordosia Lu, 1954 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Corynexochida (Order) > Shirakiellidae (Family)

Oreades
     Oreades Vandel, 1968 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Isopoda (Order) > Philosciidae (Family)
     Oreades Thompson & Brewer, 2000 accepted as Oreades Thompson & Brewer, 2000 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Stylommatophora (awaiting allocation) (Family)
 Oreades Schinz, 1845 accepted as Boselaphus de Blainville, 1816 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Artiodactyla (Order) > Bovidae (Family)

Oreamnus
 Oreamnus Elliot, 1901 accepted as Oreamnos Rafinesque, 1817 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Artiodactyla (Order) > Bovidae (Family)
 Oreamnus Agassiz, 1846 accepted as Oreamnos Rafinesque, 1817 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Artiodactyla (Order) > Bovidae (Family)

Oreas
 Oreas S.E. Bridel ex S.O. Lindberg, 1878 accepted as · Plantae (Kingdom) > Bryophyta (Phylum) > Bryopsida (Class) > Bryales (Order) > Bryaceae (Family)
     Oreas Felder, 1865 accepted as Oreas Felder, 1865 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Riodinidae (Family)
 Oreas Agassiz, 1846 accepted as Oreas Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Galliformes (Order) > Galliformes (awaiting allocation) (Family)
     Oreas S.E. Bridel, 1826 · Plantae (Kingdom) > Bryophyta (Phylum) > Bryopsida (Class) > Dicranales (Order) > Dicranaceae (Family)
 Oreas Chamisso & Schlechtendal, 1826 accepted as Aphragmus Andrzeiowski ex A.P. de Candolle, 1824 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Brassicales (Order) > Brassicaceae (Family)
 Oreas Hübner, 1807 accepted as Brintesia Fruhstorfer in Seitz, 1911 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Satyridae (Family)
 Oreas Desmarest, 1822 accepted as Taurotragus Wagner, 1855 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Artiodactyla (Order) > Bovidae (Family)
 Oreas de Montfort, 1808 accepted as Lenticulina Lamarck, 1804 (Opinion of Loeblich & Tappan, 1987) · Chromista (Kingdom) > Retaria (Phylum) > Globothalamea (Class) > Lagenida (Order) > Vaginulinidae (Family)

Orectis
     Orectis Lederer, 1857 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
 Orectis Spaeth, 1901 accepted as Parorectis Spaeth, 1901 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Orectochilus
     Orectochilus Lacordaire, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Gyrinidae (Family)
     Orectochilus Dejean, 1833 accepted as Orectochilus Lacordaire, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Gyrinidae (Family)

Oregostoma
     Oregostoma Dejean, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Oregostoma Audinet-Serville, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Oregostoma sensu Thomson, 1860 accepted as Ommata White, 1855 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Oreias
     Oreias Temminck in Temminck & Laugier, 1839 accepted as Oreias Temminck in Temminck & Laugier, 1839 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Passeriformes (awaiting allocation) (Family)
     Oreias Kaup, 1829 accepted as Oreias Kaup, 1829 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Galliformes (Order) > Galliformes (awaiting allocation) (Family)
 Oreias Sauvage, 1874 accepted as Schistura McClelland, 1838 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cypriniformes (Order) > Balitoridae (Family)

Oreina
     Oreina Westwood in Humphreys, 1841 accepted as Oreina Westwood in Humphreys, 1841 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Oreina Heer, 1847 accepted as Oreina Heer, 1847 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Oreina Dejean, 1835 accepted as Oreina Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Oreina Suffrian, 1851 accepted as Oreina Suffrian, 1851 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Oreina Chevrolat, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
 Oreina Monros & Bechyne, 1956 accepted as Chrysolina Motschoulsky in Schrenck, 1860 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
 Oreina Gistl, 1848 accepted as Schizothorax Heckel, 1838 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cypriniformes (Order) > Cyprinidae (Family)
 Oreina McNeil, 1897 accepted as Opeia McNeill, 1897 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Acrididae (Family)

Orellana
     Orellana Distant, 1905 accepted as Orellana Distant, 1905 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
 Orellana O. Kuntze, 1891 accepted as Bixa Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malvales (Order) > Bixaceae (Family)

Oreocalamus
     Oreocalamus Boulenger, 1899 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Colubridae (Family)
 Oreocalamus Y.L. Keng, 1940 accepted as Chimonobambusa Makino, 1914 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Poales (Order) > Poaceae (Family)

Oreocallis
     Oreocallis R. Brown, 1810 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Proteales (Order) > Proteaceae (Family)
 Oreocallis Small, 1914 accepted as Leucothoe D. Don, 1834 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Ericales (Order) > Ericaceae (Family)

Oreocalus
     Oreocalus Marshall, 1943 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Oreocalus May, 1993 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Oreocharis
     Oreocharis Salvadori, 1875 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Paramythiidae (Family)
     Oreocharis Bentham in Bentham & J.D. Hooker, 1876 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Gesneriaceae (Family)
 Oreocharis Broun, 1886 accepted as Oreocalus May, 1993 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Oreocharis (Decaisne) Lindley, 1846 accepted as Pseudomertensia H. Riedl in K.H. Rechinger, 1967 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Boraginales (Order) > Boraginaceae (Family)

Oreocyon
     Oreocyon Marsh, 1872 accepted as Oreocyon Marsh, 1872 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
     Oreocyon Hebauer, 2002 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Hydrophilidae (Family)
 Oreocyon Krumbiegel, 1949 accepted as Canis Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Canidae (Family)

Oreocyphon
 Oreocyphon Klausnitzer, 2008 accepted as Cyphon Paykull, 1799 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scirtidae (Family)
 Oreocyphon Klausnitzer, 2009 accepted as Dermestocyphon Pic, 1918 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scirtidae (Family)

Oreodoxites
     Oreodoxites Göppert, 1864 † accepted as Oreodoxites Göppert, 1864 † (unassessed) · Plantae (Kingdom) > Plantae (awaiting allocation) (Phylum) > Plantae (awaiting allocation) (Class) > Plantae (awaiting allocation) (Order) > Plantae (awaiting allocation) (Family)
 Oreodoxites L. Lesquereux, 1883 † accepted as Paloreodoxites Knowlton, 1930 † · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Arecales (Order) > Arecaceae (Family)

Oreoica
     Oreoica Gould, 1838 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Pachycephalidae (Family)
 Oreoica Bonaparte, 1854 accepted as Oreoica Bonaparte, 1854 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Oreokera
     Oreokera Stanisic, 1987 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Charopidae (Family)
     Oreokera Iredale, 1933 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Charopidae (Family)

Oreometra
     Oreometra Aurivillius in Sjöstedt, 1910 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
 Oreometra Clark, 1912 accepted as Reometra AH Clark, 1934 · Animalia (Kingdom) > Echinodermata (Phylum) > Crinoidea (Class) > Comatulida (Order) > Calometridae (Family)
 Oreometra AH Clark, 1912 accepted as Reometra AH Clark, 1934 (preoccupied by Oreometra Aurivillius, 1910 (Lepidoptera: Geometridae)) · Animalia (Kingdom) > Echinodermata (Phylum) > Crinoidea (Class) > Comatulida (Order) > Calometridae (Family)

Oreomyias
     Oreomyias Reichenow, 1902 accepted as Oreomyias Reichenow, 1902 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Oreomyias Berlepsch, 1907 accepted as Oreomyias Berlepsch, 1907 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Oreomys
 Oreomys Trouessart, 1881 accepted as Oreomys Trouessart, 1881 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
 Oreomys Heuglin, 1877 accepted as Otomys Cuvier, 1823 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Muridae (Family)
     Oreomys Heuglin, 1862 accepted as Otomys Cuvier, 1823 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Muridae (Family)

Oreomyza
     Oreomyza Pokorny, 1887 accepted as Oreomyza Pokorny, 1887 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Diptera (awaiting allocation) (Family)
 Oreomyza Stejneger, 1887 accepted as Oreomystis Stejneger, 1903 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Fringillidae (Family)

Oreonectes
     Oreonectes Günther, 1868 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cypriniformes (Order) > Nemacheilidae (Family)
     Oreonectes Falkenström, 1939 accepted as Oreonectes Falkenström, 1939 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)

Oreophila
     Oreophila Lackschewitz, 1935 accepted as Oreophila Lackschewitz, 1935 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Limoniidae (Family)
     Oreophila D. Don, 1830 accepted as Oreophila D. Don, 1830 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
 Oreophila Nuttall in Torrey & A. Gray, 1838 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Celastrales (Order) > Celastraceae (Family)

Oreophilus
     Oreophilus Walter, 1947 accepted as Oreophilus Walter, 1947 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Arachnida (awaiting allocation) (Order) > Arachnida (awaiting allocation) (Family)
 Oreophilus Chaudoir, 1838 accepted as Pterostichus Bonelli, 1810 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Oreophilus Gray, 1844 accepted as Oreopholus Jardine & Selby, 1835 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Charadriiformes (Order) > Charadriidae (Family)
 Oreophilus W.E. Higgins & F. Archila, 2009 accepted as Andinia (C.A. Luer) C.A. Luer, 2000 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Oreophis
     Oreophis Dugès, 1897 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Colubridae (Family)
     Oreophis Utiger, Helfenberger & Schätti in Utiger, Helfenberger, Schaetti, Schmidt, Ruf & Ziswiler, 2002 accepted as Oreophis Utiger, Helfenberger & Schätti in Utiger, Helfenberger, Schaetti, Schmidt, Ruf & Ziswiler, 2002 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Squamata (awaiting allocation) (Family)

Oreophryne
     Oreophryne Böttger, 1895 · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Anura (Order) > Microhylidae (Family)
 Oreophryne Boulenger, 1895 accepted as Oreophrynella Boulenger, 1895 · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Anura (Order) > Bufonidae (Family)

Oreophylax
     Oreophylax Hellmayr, 1925 accepted as Oreophylax Hellmayr, 1925 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Furnariidae (Family)
 Oreophylax (Endlicher) Kusnezow accepted as Gentiana Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Gentianaceae (Family)

Oreopoa
     Oreopoa H. Scholz & G. Parolly, 2004 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Poales (Order) > Poaceae (Family)
     Oreopoa M. Gandoger, 1891 accepted as Poa Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Poales (Order) > Poaceae (Family)

Oreopolus
     Oreopolus accepted as Oreopolus (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Oreopolus Schlechtendal, 1857 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Rubiaceae (Family)

Oreosaurus
     Oreosaurus Peters, 1862 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Gymnophthalmidae (Family)
     Oreosaurus Marsh, 1872 † accepted as Oreosaurus Marsh, 1872 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Anguidae (Family)

Oreoscopus
     Oreoscopus North, 1905 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Pardalotidae (Family)
 Oreoscopus Quate & Quate, 1967 accepted as Peripsychoda Enderlein, 1935 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Psychodidae (Family)

Oreospiza
     Oreospiza Keitel, 1857 accepted as Oreospiza Keitel, 1857 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Fringillidae (Family)
     Oreospiza Ridgway, 1896 accepted as Oreospiza Ridgway, 1896 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Fringillidae (Family)
 Oreospiza De Vis, 1897 accepted as Oreostruthus De Vis, 1898 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Passeridae (Family)

Oreothlypis
     Oreothlypis Stejneger, 1884 accepted as Oreothlypis Stejneger, 1884 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Oreothlypis Sangster, 2008 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Parulidae (Family)

Oresbia
     Oresbia G.V. Cron & R.B. Nordenstam, 2006 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
     Oresbia Robineau-Desvoidy, 1863 accepted as Oresbia Robineau-Desvoidy, 1863 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Tachinidae (Family)

Orescius
 Orescius Cabanis & Heine, 1863 accepted as Orescius Cabanis & Heine, 1863 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
 Orescius Bedel, 1879 accepted as Licinus Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Orestes
 Orestes Blakiston & Pryer, 1880 accepted as Orestes Blakiston & Pryer, 1880 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Paridae (Family)
     Orestes Redtenbacher in Brunner & Redtenbacher, 1906 accepted as Orestes Redtenbacher in Brunner & Redtenbacher, 1906 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Phasmatodea (Order) > Heteropterygidae (Family)
 Orestes Girty, 1911 † accepted as Phymatopleura Girty, 1939 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Vetigastropoda (Order) > Phymatopleuridae (Family)

Orestia
     Orestia Dejean, 1835 accepted as Orestia Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Orestia Redtenbacher, 1845 accepted as Orestia Redtenbacher, 1845 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Orestia Lupu, 1972 † · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Hippuritida (Order) > Hippuritida (awaiting allocation) (Family)
     Orestia Chevrolat in Dejean, 1836 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
 Orestia H.N. Ridley, 1887 accepted as Orestia H.N. Ridley, 1887 (Misspelling) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Orestia Bates, 1868 accepted as Cartea Kirby, 1871 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Riodinidae (Family)

Orestias
 Orestias Felder & Felder, 1862 accepted as Cartea Kirby, 1871 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Riodinidae (Family)
     Orestias Valenciennes, 1839 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cyprinodontiformes (Order) > Cyprinodontidae (Family)
     Orestias H.N. Ridley, 1887 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Orethelcus
     Orethelcus Reitter, 1916 accepted as Orethelcus Reitter, 1916 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
 Orethelcus Reitter, 1916 accepted as Ethelcus Reitter, 1916 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Orghidania
     Orghidania Ardoin, 1977 † accepted as Orghidania Ardoin, 1977 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)
     Orghidania Capuse, 1971 accepted as Orghidania Capuse, 1971 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Coleophoridae (Family)

Orgya
     Orgya Lefebvre, 1826 accepted as Orgya Lefebvre, 1826 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
 Orgya Zetterstedt, 1839 accepted as Orgyia Ochsenheimer, 1810 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lymantriidae (Family)

Orgyia
     Orgyia Ochsenheimer, 1810 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lymantriidae (Family)
 Orgyia Stackhouse, 1816 accepted as Alaria Greville, 1830 (synonym) · Chromista (Kingdom) > Ochrophyta (Phylum) > Phaeophyceae (Class) > Laminariales (Order) > Alariaceae (Family)

Oria
     Oria Hübner, 1821 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
     Oria Robineau-Desvoidy, 1863 accepted as Oria Robineau-Desvoidy, 1863 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Tachinidae (Family)
     Oria Distant, 1904 accepted as Oria Distant, 1904 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
 Oria Guenée, 1852 accepted as Adonisea Grote, 1875 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
     Oria Quatrefages, 1866 accepted as Oria Quatrefages, 1866 (junior homonym, invalid replacement name for Amphicorina) · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Sabellida (Order) > Sabellidae (Family)

Orias
 Orias Lydekker, 1894 accepted as Taurotragus Wagner, 1855 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Artiodactyla (Order) > Bovidae (Family)
 Orias Dode, 1909 accepted as Lagerstroemia Linnaeus, 1759 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Myrtales (Order) > Lythraceae (Family)

Oribasia
     Oribasia Duchassaing, 1850 accepted as Oribasia Duchassaing, 1850 (unassessed) · Animalia (Kingdom) > Rotifera (Phylum) > Rotifera (awaiting allocation) (Class) > Rotifera (awaiting allocation) (Order) > Rotifera (awaiting allocation) (Family)
 Oribasia Schreber, 1789 accepted as Palicourea Aublet, 1775 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Rubiaceae (Family)

Oribates
 Oribates Dugès, 1834 accepted as Lucoppia Berlese, 1908 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Oribatida (Order) > Damaeidae (Family)
 Oribates Edwards, 1881 accepted as Gyros Edwards, 1881 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Pyralidae (Family)

Oricia
     Oricia Walker, 1854 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Notodontidae (Family)
 Oricia Pierre, 1897 accepted as Vepris Commerson ex A.H.L. Jussieu, 1825 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Sapindales (Order) > Rutaceae (Family)

Oridia
     Oridia Gorham, 1895 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coccinellidae (Family)
 Oridia Rioja, 1917 accepted as Oriopsis Caullery & Mesnil, 1896 (subjective synonym) · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Sabellida (Order) > Fabriciidae (Family)

Orientalia
 Orientalia Radoman, 1972 † accepted as Radomaniola Szarowska, 2006 (invalid: junior homonym of Orientalia Bykova, 1947 [Foraminifera]; Orientalina and Radomaniola are replacement names) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Littorinimorpha (Order) > Hydrobiidae (Family)
 Orientalia Dang, 1975 accepted as Hainanpotamon Dai, 1995 (preoccupied) · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Potamidae (Family)
     Orientalia Bykova, 1947 † · Chromista (Kingdom) > Retaria (Phylum) > Globothalamea (Class) > Lituolida (Order) > Prolixoplectidae (Family)

Orientalina
     Orientalina Kolosnitsyna, 1973 † · Animalia (Kingdom) > Arthropoda (Phylum) > Ostracoda (Class) > Palaeocopida (Order) > Palaeocopida (awaiting allocation) (Family)
 Orientalina Radoman, 1978 † accepted as Radomaniola Szarowska, 2006 (invalid: junior homonym of Orientalina Kolosnitsyna, 1973 [Crustacea]; Radomaniola is a replacement name) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Littorinimorpha (Order) > Hydrobiidae (Family)

Orientis
 Orientis Huang in Huang & Boczek, 1996 accepted as Setoptus Keifer, 1944 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Actinedida (Order) > Phytoptidae (Family)
 Orientis Vats & Kashyap, 1992 accepted as Senodonia Laporte, 1836 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Elateridae (Family)

Orientolepis
     Orientolepis Pan & Wang, 1978 † accepted as Orientolepis Pan & Wang, 1978 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Chondrichthyes (Class) > Elasmobranchiomorphi (awaiting allocation) (Order) > Elasmobranchiomorphi (awaiting allocation) (Family)
 Orientolepis Spassky & Yurpalova, 1964 accepted as Microsomacanthus López-Neyra, 1942 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Cestoda (Class) > Cyclophyllidea (Order) > Hymenolepididae (Family)

Origostrophia
     Origostrophia Mitchell, 1972 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Strophomenata (Class) > Strophomenatida (Order) > Eopholidostrophiidae (Family)
     Origostrophia Imbrie, 1959 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Strophomenata (Class) > Strophomenatida (Order) > Schuchertellidae (Family)

Orina
 Orina Agassiz, 1846 accepted as Orina Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Orina Adams, 1870 accepted as Orina Adams, 1870 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Heterostropha (Order) > Pyramidellidae (Family)
 Orina Weise, 1884 accepted as Oreina Chevrolat, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
 Orina Gray, 1867 accepted as Haliclona Grant, 1841 (junior synonym) · Animalia (Kingdom) > Porifera (Phylum) > Demospongea (Class) > Haplosclerida (Order) > Chalinidae (Family)

Orinomus
     Orinomus Attems, 1895 accepted as Orinomus Attems, 1895 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Chilopoda (Class) > Geophilomorpha (Order) > Geophilidae (Family)
 Orinomus Chamberlin, 1916 accepted as Orinomana Strand, 1934 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Uloboridae (Family)

Orinus
     Orinus Nitzsch, 1833 accepted as Orinus Nitzsch, 1833 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Orinus Hitchcock, 1933 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Poales (Order) > Poaceae (Family)
 Orinus Agassiz, 1846 accepted as Schizothorax Heckel, 1838 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cypriniformes (Order) > Cyprinidae (Family)

Oriola
 Oriola Giebel, 1875 accepted as Oriolia Geoffroy, 1838 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Corvidae (Family)
 Oriola Baker, 1968 accepted as Proctotydaeus Berlese, 1911 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Actinedida (Order) > Iolinidae (Family)

Oriolus
     Oriolus Linnaeus, 1766 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Oriolidae (Family)
 Oriolus Brisson, 1760 accepted as Oriolus Linnaeus, 1766 (Suppressed name (ICZN)) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Oriolidae (Family)

Orion
     Orion Guérin-Ménéville, 1844 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Orion Dejean, 1835 accepted as Orion Guérin-Ménéville, 1844 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Orissus
     Orissus Pascoe, 1889 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Orissus A. Costa in O. Costa, 1860 accepted as Orussus Latreille, 1796 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Orussidae (Family)

Orites
     Orites Keyserling & Blasius, 1840 accepted as Orites Keyserling & Blasius, 1840 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Fringillidae (Family)
     Orites Gray, 1841 accepted as Orites Gray, 1841 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Paridae (Family)
 Orites Möhring, 1758 accepted as Orites Möhring, 1758 (Published in a rejected work (ICZN)) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Paridae (Family)
 Orites Agassiz, 1846 accepted as Orites Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Orites R. Brown, 1810 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Proteales (Order) > Proteaceae (Family)
 Orites Schaum in Erichson, 1858 accepted as Pterostichus Bonelli, 1810 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Orithya
 Orithya Risso, 1826 accepted as Orithya Risso, 1826 (Misspelling) · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Hydrozoa (awaiting allocation) (Order) > Hydrozoa (awaiting allocation) (Family)
 Orithya Bosc, 1802 accepted as Orithyia Fabricius, 1798 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Orithyiidae (Family)

Orithyia
     Orithyia Fabricius, 1798 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Orithyiidae (Family)
     Orithyia Blackwall, 1858 accepted as Orithyia Blackwall, 1858 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Arachnida (awaiting allocation) (Order) > Arachnida (awaiting allocation) (Family)
 Orithyia Agassiz, 1846 accepted as Orithyia Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Hydrozoa (awaiting allocation) (Order) > Hydrozoa (awaiting allocation) (Family)
 Orithyia Johnston, 1836 accepted as Phoxichilidium Milne Edwards, 1840 · Animalia (Kingdom) > Arthropoda (Phylum) > Pycnogonida (Class) > Pantopoda (Order) > Phoxichilidiidae (Family)
 Orithyia D. Don in Sweet, 1836 accepted as Tulipa Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Liliales (Order) > Liliaceae (Family)
     Orithyia Smith, 2011 † · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Iguanidae (Family)

Orithyja
 Orithyja Oken, 1815 accepted as Orithyja Oken, 1815 (Misspelling) · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Hydrozoa (awaiting allocation) (Order) > Hydrozoa (awaiting allocation) (Family)
 Orithyja Herbst, 1799 accepted as Orithyia Fabricius, 1798 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Orithyiidae (Family)

Oritiscus
     Oritiscus Bonaparte, 1854 accepted as Oritiscus Bonaparte, 1854 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Aegithalidae (Family)
 Oritiscus Gray, 1855 accepted as Oritiscus Gray, 1855 (Unjustified (?) emendation) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Aegithalidae (Family)

Orixa
     Orixa Thunberg, 1783 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Sapindales (Order) > Rutaceae (Family)
 Orixa Walker in Chapman, 1869 accepted as Xoria Nye, 1975 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
 Orixa Leach in Gray, 1852 accepted as Abra Lamarck, 1818 (synonym) · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Semelidae (Family)

Ormenis
     Ormenis Stål, 1860 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Flatidae (Family)
 Ormenis (Cassini) Cassini in F. Cuvier, 1823 accepted as Chamaemelum P. Miller, 1754 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)

Ormiscus
     Ormiscus Waterhouse, 1845 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Anthribidae (Family)
     Ormiscus (A.P. de Candolle) Ecklon & Zeyher, 1835 accepted as Ormiscus (A.P. de Candolle) Ecklon & Zeyher, 1835 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Brassicales (Order) > Brassicaceae (Family)

Ormistonia
     Ormistonia Maksimova, 1978 † accepted as Ormistonia Maksimova, 1978 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Trilobita (awaiting allocation) (Order) > Trilobita (awaiting allocation) (Family)
     Ormistonia Li, 1994 † accepted as Ormistonia Li, 1994 † (unassessed) · Protozoa (Kingdom) > (Phylum) > (Class) > Sarcomastigota (awaiting allocation) (Order) > Sarcomastigota (awaiting allocation) (Family)

Ormosia
     Ormosia Rondani, 1856 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Limoniidae (Family)
     Ormosia G. Jackson, 1811 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)

Ornatella
     Ornatella Canu, 1900 † accepted as Ornatella Canu, 1900 † (unassessed) · Animalia (Kingdom) > Bryozoa (Phylum) > Bryozoa (awaiting allocation) (Class) > Bryozoa (awaiting allocation) (Order) > Bryozoa (awaiting allocation) (Family)
     Ornatella Rozhdestvenskaya in Chibrikova & Rozhdestvenskaya, 1959 † accepted as Ornatella Rozhdestvenskaya in Chibrikova & Rozhdestvenskaya, 1959 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Ostracoda (Class) > Ostracoda (awaiting allocation) (Order) > Ostracoda (awaiting allocation) (Family)

Ornatisporites
     Ornatisporites M.G. Parsons & G. Norris, 1999 † · Fungi (Kingdom) > Fungi (awaiting allocation) (Phylum) > Fungi (awaiting allocation) (Class) > Fungi (awaiting allocation) (Order) > Fungi (awaiting allocation) (Family)
     Ornatisporites E. Nagy, 1963 † accepted as Ornatisporites E. Nagy, 1963 † (unassessed) · Plantae (Kingdom) > Sporae dispersae (Phylum) > (Class) > (Order) > (Family)

Ornatoptygmatis
     Ornatoptygmatis Lyssenko, 1981 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Neogastropoda (Order) > Neogastropoda (awaiting allocation) (Family)
     Ornatoptygmatis Lyssenko, 1990 † accepted as Ornatoptygmatis Lyssenko, 1990 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Gastropoda (awaiting allocation) (Order) > Gastropoda (awaiting allocation) (Family)

Ornatus
     Ornatus de Laubenfels in Moore, 1955 † · Animalia (Kingdom) > Porifera (Phylum) > Hexactinellida (Class) > Lychniscosida (Order) > Lychniscosa (awaiting allocation) (Family)
 Ornatus Korboot, 1964 accepted as Tanorus Neboiss, 1984 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Trichoptera (Order) > Hydrobiosidae (Family)

Orneates
     Orneates Godman & Salvin, 1894 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Hesperiidae (Family)
     Orneates Jacoby, 1899 accepted as Orneates Jacoby, 1899 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
 Orneates Sharp, 1899 accepted as Gabonia Jacoby, 1893 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Ornistomus
     Ornistomus Thomson, 1864 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Ornistomus Dejean, 1835 accepted as Ornistomus Thomson, 1864 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Ornithaptera
 Ornithaptera Bonaparte, 1856 accepted as Threskiornis Gray, 1842 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Ciconiiformes (Order) > Threskiornithidae (Family)
     Ornithaptera Bonaparte, 1854 accepted as Threskiornis Gray, 1842 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Ciconiiformes (Order) > Threskiornithidae (Family)

Ornithichnites
     Ornithichnites King, 1845 accepted as Ornithichnites King, 1845 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Amphibia (awaiting allocation) (Order) > Amphibia (awaiting allocation) (Family)
     Ornithichnites Portis, 1859 † accepted as Ornithichnites Portis, 1859 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)
     Ornithichnites Hitchcock, 1836 † accepted as Ornithichnites Hitchcock, 1836 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)

Ornithocephalus
     Ornithocephalus W.J. Hooker, 1824 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
 Ornithocephalus Sömmering, 1812 † accepted as Pterodactylus Cuvier, 1809 † · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Pterosauria (Order) > Pterodactylidae (Family)
 Ornithocephalus Semenov, 1887 accepted as Carabus Linnaeus, 1758 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Ornitholithus
     Ornitholithus Dughi & Sirugue, 1962 † accepted as Ornitholithus Dughi & Sirugue, 1962 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Diatrymiformes (Order) > Diatrymiformes (awaiting allocation) (Family)
     Ornitholithus Dughi & Sirugue, 1962 † accepted as Ornitholithus Dughi & Sirugue, 1962 † · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Diatrymiformes (Order) > Diatrymiformes (awaiting allocation) (Family)
 Ornitholithus Linnaeus, 1768 accepted as Ornitholithus Linnaeus, 1768 (Published in a rejected work (ICZN)) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Ornithomyia
     Ornithomyia Bonaparte, 1854 accepted as Ornithomyia Bonaparte, 1854 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
 Ornithomyia Latreille, 1805 accepted as Ornithomya Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Hippoboscidae (Family)

Ornithopsis
     Ornithopsis Seeley, 1870 † accepted as Ornithopsis Seeley, 1870 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Saurischia (Order) > Brachiosauridae (Family)
 Ornithopsis Cossmann, 1925 † accepted as Ornopsis Wade, 1916 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Neogastropoda (Order) > Fasciolariidae (Family)

Ornithopteris
 Ornithopteris Bernhardi, 1805 accepted as Anemia O. Swartz, 1806 · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Schizaeales (Order) > Anemiaceae (Family)
 Ornithopteris (J.G. Agardh) J. Smith, 1875 accepted as Pteridium Gleditsch ex Scopoli, 1760 · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Polypodiales (Order) > Dennstaedtiaceae (Family)

Ornithopterus
     Ornithopterus Meyer, 1838 accepted as Ornithopterus Meyer, 1838 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)
 Ornithopterus Westwood, 1839 accepted as Ornithoptera Boisduval in d'Urville, 1932 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Papilionidae (Family)

Ornithopus
     Ornithopus Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)
     Ornithopus Hitchcock, 1848 accepted as Ornithopus Hitchcock, 1848 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)
 Ornithopus J. S. Gardner, 1875 † accepted as Tessarolax Gabb, 1864 † (invalid: junior homonym of Ornithopus Hitchcock, 1848 [Reptilia]) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Littorinimorpha (Order) > Aporrhaidae (Family)

Ornithoramphus
     Ornithoramphus Natale, 1850 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Amphipoda (Order) > Oxycephalidae (Family)
     Ornithoramphus Cocco in Natale, 1850 accepted as Ornithoramphus Cocco in Natale, 1850 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Crustacea (awaiting allocation) (Class) > Crustacea (awaiting allocation) (Order) > Crustacea (awaiting allocation) (Family)

Ornithorinchus
 Ornithorinchus Rafinesque, 1815 accepted as Ornithorhynchus Blumenbach, 1800 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Monotremata (Order) > Ornithorhynchidae (Family)
 Ornithorinchus Artaud, 1803 accepted as Ornithorhynchus Blumenbach, 1800 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Monotremata (Order) > Ornithorhynchidae (Family)

Oroba
     Oroba Walker, 1863 accepted as Oroba Walker, 1863 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Oroba Medikus, 1787 accepted as Oroba Medikus, 1787 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)

Orobates
     Orobates Berman, Henrici, Kissel, Sumida & Martens, 2004 † accepted as Orobates Berman, Henrici, Kissel, Sumida & Martens, 2004 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Anthracosauria (Order) > Anthracosauria (awaiting allocation) (Family)
 Orobates Agassiz, 1846 accepted as Lucoppia Berlese, 1908 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Oribatida (Order) > Damaeidae (Family)

Orobia
     Orobia Stål, 1875 accepted as Orobia Stål, 1875 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Phasmatodea (Order) > Phasmatidae (Family)
     Orobia Martens, 1860 accepted as Orobia Martens, 1860 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Orobias
     Orobias Eichwald, 1860 accepted as Orobias Eichwald, 1860 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)
     Orobias Galloway & Harlton, 1928 † accepted as Orobias Galloway & Harlton, 1928 † (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)

Orobites
 Orobites Schoenherr, 1833 accepted as Orobitis Germar, 1817 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Orobites Billberg, 1820 accepted as Orobitis Germar, 1817 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Orodalus
     Orodalus Mulsant & Rey, 1870 accepted as Orodalus Mulsant & Rey, 1870 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Orodalus Balthasar, 1936 accepted as Aphodius Illiger in Kugelann, 1798 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Orodes
     Orodes Jacoby, 1891 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Orodes Geyer, 1990 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Ptychopariida (Order) > Ellipsocephalidae (Family)

Orodina
 Orodina Gistl, 1848 accepted as Orodina Gistl, 1848 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
 Orodina Calder, 1986 accepted as Arachnodima Candèze, 1893 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Elateridae (Family)

Orodinus
 Orodinus Dahl, 1823 accepted as Orodinus Dahl, 1823 (Published in a suppressed work (ICZN)) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Orodinus Gistl, 1848 accepted as Psuchocephalus Latreille, 1828 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Orodus
     Orodus Agassiz, 1838 † · Animalia (Kingdom) > Chordata (Phylum) > Chondrichthyes (Class) > Orodontiformes (Order) > Orodontidae (Family)
     Orodus Agassiz in Egerton, 1837 † accepted as Orodus Agassiz in Egerton, 1837 † · Animalia (Kingdom) > Chordata (Phylum) > Chondrichthyes (Class) > Orodontiformes (Order) > Orodontidae (Family)

Oroessa
     Oroessa Usinger & Matsuda, 1959 accepted as Oroessa Usinger & Matsuda, 1959 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Oroessa Kirichenko, 1959 accepted as Oroessa Kirichenko, 1959 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)

Orolestes
     Orolestes McLachlan, 1895 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Odonata (Order) > Chlorolestidae (Family)
 Orolestes Thomas, 1917 accepted as Lestoros Oehser, 1934 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Paucituberculata (Order) > Caenolestidae (Family)

Oromeryx
     Oromeryx Marsh, 1894 accepted as Oromeryx Marsh, 1894 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
     Oromeryx Marsh, 1878 accepted as Oromeryx Marsh, 1878 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)

Oromia
     Oromia Lopez-Colon, 1989 accepted as Oromia Lopez-Colon, 1989 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Oromia Alonso Zarazaga, 1987 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Oromys
     Oromys Leidy, 1853 accepted as Oromys Leidy, 1853 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
 Oromys Robinson & Kloss, 1916 accepted as Mus Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Muridae (Family)

Orona
     Orona Cameron in Baker, 1905 accepted as Orona Cameron in Baker, 1905 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
     Orona Haeckel, 1887 accepted as Orona Haeckel, 1887 (unassessed) · Chromista (Kingdom) > Retaria (Phylum) > Polycystinea (Class) > Polycystinea (awaiting allocation) (Order) > Radiolaria (awaiting allocation) (Family)

Oronotus
     Oronotus Wesmael, 1844 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Ichneumonidae (Family)
 Oronotus Gemminger & Harold, 1869 accepted as Oronotus Gemminger & Harold, 1869 (Unjustified (?) emendation) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Orontium
     Orontium Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Alismatales (Order) > Araceae (Family)
 Orontium Persoon, 1806 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Scrophulariaceae (Family)

Orophia
     Orophia Hübner, 1825 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Oecophoridae (Family)
 Orophia Meyrick, 1883 accepted as Philobota Meyrick, 1883 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Oecophoridae (Family)

Orophila
     Orophila Staudinger in Staudinger & Schatz, 1886 accepted as Orophila Staudinger in Staudinger & Schatz, 1886 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
 Orophila Krauss, 1892 accepted as Canariola Uvarov, 1940 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tettigoniidae (Family)

Orosphaera
     Orosphaera Haeckel, 1887 · Chromista (Kingdom) > Retaria (Phylum) > Polycystinea (Class) > Spumellaria (Order) > Orosphaeridae (Family)
     Orosphaera Haeckel, 1881 accepted as Orosphaera Haeckel, 1881 · Chromista (Kingdom) > Cercozoa (Phylum) > Thecofilosea (Class) > Phaeodaria (awaiting allocation) (Order) > Phaeodaria (awaiting allocation) (Family)

Orospina
     Orospina Kaup, 1829 accepted as Orospina Kaup, 1829 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Orospina Cabanis, 1883 accepted as Orospina Cabanis, 1883 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Orostachys
     Orostachys F.E.L. Fischer, 1809 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Saxifragales (Order) > Crassulaceae (Family)
 Orostachys E.G. von Steudel, 1841 accepted as Hordelymus (Jessen) Harz, 1885 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Poales (Order) > Poaceae (Family)

Orothamnus
     Orothamnus Pappe ex W.J. Hooker, 1848 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Proteales (Order) > Proteaceae (Family)
     Orothamnus Haeckel, 1887 accepted as Orothamnus Haeckel, 1887 (unassessed) · Chromista (Kingdom) > Retaria (Phylum) > Polycystinea (Class) > Polycystinea (awaiting allocation) (Order) > Radiolaria (awaiting allocation) (Family)

Orotherium
     Orotherium Marsh, 1872 accepted as Orotherium Marsh, 1872 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Perissodactyla (Order) > Equidae (Family)
     Orotherium Aymard, 1850 accepted as Orotherium Aymard, 1850 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Artiodactyla (Order) > Cervidae (Family)

Oroya
     Oroya Miller, 1994 accepted as Oroya Miller, 1994 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Dalceridae (Family)
     Oroya N.L. Britton & J.N. Rose, 1922 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Caryophyllales (Order) > Cactaceae (Family)

Orphania
     Orphania Fischer, 1853 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tettigoniidae (Family)
 Orphania Spence Bate, 1888 accepted as Parapasiphae Smith, 1884 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Pasiphaeidae (Family)

Orphanus
 Orphanus Agassiz, 1846 accepted as Orphanus Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
 Orphanus Herrich-Schäffer, ? 1853 accepted as Orphanus Herrich-Schäffer, ? 1853 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)

Orpheus
     Orpheus Temminck & Schlegel in Siebold, 1848 accepted as Orpheus Temminck & Schlegel in Siebold, 1848 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Orpheus Swainson, 1827 accepted as Orpheus Swainson, 1827 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Orphne
     Orphne Hübner, 1825 accepted as Orphne Hübner, 1825 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Orphne Hagen, 1866 accepted as Orphne Hagen, 1866 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Neuroptera (Order) > Neuroptera (awaiting allocation) (Family)

Orphnus
     Orphnus Macleay, 1819 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Orphnus Agassiz, 1844 accepted as Orphnus Agassiz, 1844 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Neuroptera (Order) > Neuroptera (awaiting allocation) (Family)
     Orphnus Albers, 1850 accepted as Orphnus Albers, 1850 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Orsa
     Orsa Walker, 1865 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
     Orsa Silhavy, 1979 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Opiliones (Order) > Samoidae (Family)

Orsilochus
     Orsilochus Burmeister, 1847 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Orsilochus Stål, 1867 accepted as Orsilochus Stål, 1867 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
 Orsilochus Attems, 1900 accepted as Rhinotus Cook, 1896 · Animalia (Kingdom) > Arthropoda (Phylum) > Diplopoda (Class) > Polyzoniida (Order) > Siphonotidae (Family)

Ortalis
     Ortalis Merrem, 1786 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Galliformes (Order) > Cracidae (Family)
     Ortalis Fallén, 1810 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Ulidiidae (Family)

Ortega
     Ortega Melichar, 1924 accepted as Ortega Melichar, 1924 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
 Ortega Linnaeus, 1753 accepted as Ortegia Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Caryophyllales (Order) > Caryophyllaceae (Family)

Orthacanthus
     Orthacanthus Agassiz, 1843 † accepted as Orthacanthus Agassiz, 1843 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Chondrichthyes (Class) > Xenacanthiformes (Order) > Xenacanthidae (Family)
     Orthacanthus P.M. Peterson & K. Romaschenko, 2016 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Poales (Order) > Poaceae (Family)

Orthaea
     Orthaea Dallas, 1852 accepted as Orthaea Dallas, 1852 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Rhyparochromidae (Family)
     Orthaea Klotzsch, 1851 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Ericales (Order) > Ericaceae (Family)
 Orthaea Jacoby, 1889 accepted as Euphitrea Baly, 1875 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Orthagoriscus
     Orthagoriscus Schneider, 1801 accepted as Orthagoriscus Schneider, 1801 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Pisces (awaiting allocation) (Class) > Pisces (awaiting allocation) (Order) > Pisces (awaiting allocation) (Family)
 Orthagoriscus Cuvier, 1816 accepted as Mola Koelreuter, 1766 (synonym) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Tetraodontiformes (Order) > Molidae (Family)

Orthandra
 Orthandra Pichon, 1953 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Apocynaceae (Family)
 Orthandra Burret, 1940 accepted as Mortoniodendron Standley & Steyermark, 1938 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malvales (Order) > Malvaceae (Family)

Orthanthus
 Orthanthus Mortensen, 1948 accepted as Clypeaster Lamarck, 1801 ((sub)generic subdivision of Clypeaster not accepted by scientific community) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Clypeasteroida (Order) > Clypeasteridae (Family)
 Orthanthus H.L. Clark, 1941 accepted as Clypeaster Lamarck, 1801 · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Clypeasteroida (Order) > Clypeasteridae (Family)

Orthezia
     Orthezia Bosc, 1784 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Ortheziidae (Family)
 Orthezia Kriechbaumer, 1898 accepted as Ortezia Cresson, 1873 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Ichneumonidae (Family)

Orthia
     Orthia Herrich-Schäffer, 1856 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
     Orthia Reichenbach, 1863 accepted as Orthia Reichenbach, 1863 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)

Orthobracon
     Orthobracon Fahringer, 1927 accepted as Orthobracon Fahringer, 1927 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
     Orthobracon Tobias, 1957 accepted as Orthobracon Tobias, 1957 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Braconidae (Family)

Orthocarpus
     Orthocarpus Hoek, 1879 accepted as Orthocarpus Hoek, 1879 · Animalia (Kingdom) > Arthropoda (Phylum) > Crustacea (awaiting allocation) (Class) > Crustacea (awaiting allocation) (Order) > Crustacea (awaiting allocation) (Family)
     Orthocarpus Nuttall, 1818 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Orobanchaceae (Family)

Orthocentrus
     Orthocentrus Gravenhorst, 1829 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Ichneumonidae (Family)
     Orthocentrus Scudder, 1882 accepted as Orthocentrus Scudder, 1882 · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Orthocephalus
     Orthocephalus Fieber, 1858 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Miridae (Family)
 Orthocephalus Pascoe, 1862 accepted as Pseudocephalus Newman, 1842 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Orthocera
 Orthocera Lamarck, 1799 † accepted as Orthocera Lamarck, 1799 † (Misspelling) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Orthocerida (Order) > Orthoceratidae (Family)
     Orthocera Modeer in Soldani, 1789 accepted as Orthocera Modeer in Soldani, 1789 · Chromista (Kingdom) > Retaria (Phylum) > Globothalamea (Class) > Textulariida (Order) > Textulariidae (Family)

Orthoceras
     Orthoceras Schrank, 1796 accepted as Orthoceras Schrank, 1796 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Dolichopodidae (Family)
     Orthoceras Bruguière, 1789 † · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Orthocerida (Order) > Orthoceratidae (Family)
     Orthoceras R. Brown, 1810 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
     Orthoceras Blainville, 1825 accepted as Orthoceras Blainville, 1825 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)

Orthoceratites
 Orthoceratites Gesner, 1758 † accepted as (unavailable name (suppressed work)) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Orthocerida (Order) > Orthoceratidae (Family)
 Orthoceratites Lamarck, 1799 † accepted as Hippurites Lamarck, 1801 † (unavailable name (suppressed by ICZN Opinion)) · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Hippuritida (Order) > Hippuritidae (Family)

Orthoceros
     Orthoceros Brünnich, 1771 accepted as Orthoceros Brünnich, 1771 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Orthoceros Da Costa, 1776 accepted as Orthoceros Da Costa, 1776 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)

Orthocerus
     Orthocerus Latreille, 1796 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Zopheridae (Family)
 Orthocerus King, 1844 † accepted as Orthocerus King, 1844 † (Misspelling) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Orthocerida (Order) > Orthoceratidae (Family)

Orthochaeta
 Orthochaeta Hendel, 1930 accepted as Orthacheta Becker, 1894 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Scathophagidae (Family)
 Orthochaeta Sawada, 1943 accepted as Erysiphe R. Hedwig ex A.P. de Candolle, 1805 · Fungi (Kingdom) > Ascomycota (Phylum) > Leotiomycetes (Class) > Erysiphales (Order) > Erysiphaceae (Family)

Orthochilus
     Orthochilus Cossmann, 1889 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Sorbeoconcha (Order) > Planaxidae (Family)
 Orthochilus Hochstetter ex A. Richard, 1850 accepted as Eulophia R. Brown, 1821 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Orthochtha
     Orthochtha Karsch, 1891 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Acrididae (Family)
     Orthochtha Meyrick, 1928 accepted as Orthochtha Meyrick, 1928 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)

Orthocidaris
     Orthocidaris Cotteau in d'Orbigny, 1862 † · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Pedinoida (Order) > Pedinidae (Family)
 Orthocidaris A. Agassiz, 1863 accepted as Cidaris Leske, 1778 (preoccupied (non Cotteau, 1862); subjective junior synonym of Cidaris) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Cidaroida (Order) > Cidaridae (Family)

Orthocnemus
     Orthocnemus Milne-Edwards, 1892 † accepted as Orthocnemus Milne-Edwards, 1892 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Gruiformes (Order) > Idiornithidae (Family)
     Orthocnemus Jekel, 1854 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Orthoconchoecia
     Orthoconchoecia Martens, 1979 · Animalia (Kingdom) > Arthropoda (Phylum) > Ostracoda (Class) > Halocyprida (Order) > Halocyprididae (Family)
     Orthoconchoecia Granata & Caporiacco, 1949 · Animalia (Kingdom) > Arthropoda (Phylum) > Ostracoda (Class) > Halocyprida (Order) > Halocyprididae (Family)

Orthocosta
     Orthocosta Fritsch, 1879 † accepted as Orthocosta Fritsch, 1879 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Microsauria (Order) > Microbrachidae (Family)
     Orthocosta Bolton, 1912 † accepted as Orthocosta Bolton, 1912 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Palaeodictyoptera (Order) > Palaeodictyoptera (awaiting allocation) (Family)

Orthocraspeda
     Orthocraspeda Hampson, 1893 accepted as Orthocraspeda Hampson, 1893 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Limacodidae (Family)
 Orthocraspeda Prout, 1912 accepted as Orthorisma Prout, 1912 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)

Orthocyathus
     Orthocyathus Vologdin, 1977 † accepted as Orthocyathus Vologdin, 1977 † (unassessed) · Animalia (Kingdom) > Archaeocyatha (Phylum) > Regulares (Class) > Regulares (awaiting allocation) (Order) > Regulares (awaiting allocation) (Family)
     Orthocyathus Merriam, 1973 † · Animalia (Kingdom) > Cnidaria (Phylum) > Anthozoa (Class) > Rugosa (Order) > Cyathophyllidae (Family)

Orthodactylus
 Orthodactylus Karsch, 1881 accepted as Orthochirus Karsch, 1892 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Scorpiones (Order) > Buthidae (Family)
 Orthodactylus Hitchcock, 1858 † accepted as Batrachopus Hitchcock, 1845 † · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Crocodylia (Order) > Batrachopodidae (Family)

Orthodon
     Orthodon Rafinesque, 1815 accepted as Orthodon Rafinesque, 1815 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
     Orthodon Girard, 1856 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Cypriniformes (Order) > Cyprinidae (Family)
     Orthodon Coquand, 1860 accepted as Orthodon Coquand, 1860 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Pisces (awaiting allocation) (Class) > Pisces (awaiting allocation) (Order) > Pisces (awaiting allocation) (Family)
     Orthodon R. Brown, 1819 accepted as Orthodon R. Brown, 1819 (unassessed) · Plantae (Kingdom) > Bryophyta (Phylum) > Bryopsida (Class) > Splachnales (Order) > Splachnaceae (Family)
 Orthodon Gruber, 1884 accepted as Orthodonella Bhatia, 1936 · Chromista (Kingdom) > Ciliophora (Phylum) > Nassophorea (Class) > Synhymeniida (Order) > Orthodonellidae (Family)
 Orthodon Bentham in Oliver, 1865 accepted as Mosla (Bentham) F. [Buchanan] Hamilton ex Maximowicz, 1875 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Lamiaceae (Family)

Orthogenium
     Orthogenium Chaudoir, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Orthogenium Roth, 1901 † accepted as Orthogeniops Ameghino, 1902 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Notoungulata (Order) > Acoelodidae (Family)

Orthognathus
     Orthognathus Buquet, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Dryophthoridae (Family)
     Orthognathus Schönherr, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Orthognathus Barkas, 1873 accepted as Orthognathus Barkas, 1873 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Pisces (awaiting allocation) (Class) > Pisces (awaiting allocation) (Order) > Pisces (awaiting allocation) (Family)
 Orthognathus Dejean, 1837 accepted as Sphenognathus Buquet, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Lucanidae (Family)
     Orthognathus Folkmanova, 1958 accepted as Orthognathus Folkmanova, 1958 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Chilopoda (Class) > Chilopoda (awaiting allocation) (Order) > Chilopoda (awaiting allocation) (Family)

Orthogonoderus
 Orthogonoderus Germain, 1855 accepted as Orthogonoderus Germain, 1855 (Unjustified (?) emendation) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
 Orthogonoderus Solier in Gay, 1851 accepted as Praocis Eschscholtz, 1829 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Orthogramma
     Orthogramma Guenée, 1852 accepted as Orthogramma Guenée, 1852 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
     Orthogramma Reichenbach, 1817 accepted as Orthogramma Reichenbach, 1817 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
 Orthogramma K.B. Presl, 1851 accepted as Blechnum Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Polypodiales (Order) > Blechnaceae (Family)
 Orthogramma Murray, 1864 accepted as Platynema Ritsema, 1885 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Nitidulidae (Family)

Ortholophus
     Ortholophus Ogilvie-Grant, 1892 accepted as Ortholophus Ogilvie-Grant, 1892 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Coraciiformes (Order) > Bucerotidae (Family)
     Ortholophus Duncan, 1887 † · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Camarodonta (Order) > Trigonocidaridae (Family)
     Ortholophus Bigot, 1882 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Syrphidae (Family)
     Ortholophus Walsingham, 1887 accepted as Ortholophus Walsingham, 1887 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)

Orthomerus
     Orthomerus Seeley, 1883 † · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Ornithischia (Order) > Hadrosauridae (Family)
 Orthomerus Campion, 1908 accepted as Orthomerinus Champion, 1908 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Orthomorphina
     Orthomorphina Stainforth, 1952 † · Chromista (Kingdom) > Retaria (Phylum) > Globothalamea (Class) > Lagenida (Order) > Glandulonodosariidae (Family)
 Orthomorphina Kraus, 1958 † accepted as Orthomorphina Stainforth, 1952 † · Chromista (Kingdom) > Retaria (Phylum) > Globothalamea (Class) > Lagenida (Order) > Nodosariidae (Family)

Orthomus
     Orthomus Chaudoir, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Orthomus Motschulsky, 1850 accepted as Pterostichus Bonelli, 1810 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Orthonata
 Orthonata Hall, 1843 † accepted as Orthonata Hall, 1843 † (Misspelling) · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Unionoida (Order) > Iridinidae (Family)
 Orthonata Herrmannsen, 1842 † accepted as Orthonata Herrmannsen, 1842 † (Misspelling) · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Unionoida (Order) > Iridinidae (Family)

Orthoneura
 Orthoneura Loew, 1843 accepted as Orthonevra Macquart, 1829 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Syrphidae (Family)
 Orthoneura Blood & Kryger, 1928 accepted as Tumidiclava Girault, 1911 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Trichogrammatidae (Family)

Orthonotus
     Orthonotus Westwood in Stephens, 1829 accepted as Orthonotus Westwood in Stephens, 1829 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Orthonotus Ashmead, 1905 accepted as Orthonotus Ashmead, 1905 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)

Orthoplana
     Orthoplana Kohler, 1933 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Turbellaria (Class) > Proseriata (Order) > Otoplanidae (Family)
     Orthoplana Steinböck, 1932 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Turbellaria (Class) > Proseriata (Order) > Otoplanidae (Family)

Orthopleura
     Orthopleura Imbrie, 1959 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Strophomenata (Class) > Orthotetida (Order) > Areostrophiidae (Family)
 Orthopleura Spinola, 1844 accepted as Dermestoides Schaeffer, 1771 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cleridae (Family)

Orthopora
     Orthopora Hall, 1886 † · Animalia (Kingdom) > Bryozoa (Phylum) > Stenolaemata (Class) > Cryptostomida (Order) > Rhabdomesidae (Family)
 Orthopora Waters, 1904 † accepted as Orthoporidra Canu & Bassler, 1927 · Animalia (Kingdom) > Bryozoa (Phylum) > Gymnolaemata (Class) > Cheilostomatida (Order) > Lekythoporidae (Family)

Orthops
     Orthops Franganillo, 1926 accepted as Orthops Franganillo, 1926 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Arachnida (awaiting allocation) (Order) > Arachnida (awaiting allocation) (Family)
     Orthops Fieber, 1858 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Miridae (Family)

Orthopus
     Orthopus Wulfsberg, 1876 accepted as Orthopus Wulfsberg, 1876 (unassessed) · Plantae (Kingdom) > Bryophyta (Phylum) > Bryopsida (Class) > Dicranales (Order) > Dicranaceae (Family)
     Orthopus Kutorga, 1838 accepted as Orthopus Kutorga, 1838 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)

Orthopyxis
     Orthopyxis Palisot de Beauvois, 1805 accepted as Orthopyxis Palisot de Beauvois, 1805 (unassessed) · Plantae (Kingdom) > Bryophyta (Phylum) > Bryopsida (Class) > Bryales (Order) > Aulacomniaceae (Family)
     Orthopyxis L. Agassiz, 1862 · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Leptothecata (Order) > Campanulariidae (Family)

Orthorchis
     Orthorchis Mödlinger, 1925 accepted as Orthorchis Mödlinger, 1925 (unassessed) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Trematoda (awaiting allocation) (Order) > Trematoda (awaiting allocation) (Family)
     Orthorchis Travassos, 1944 accepted as Orthorchis Travassos, 1944 (unassessed) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Trematoda (awaiting allocation) (Order) > Trematoda (awaiting allocation) (Family)

Orthorhinus
     Orthorhinus Blyth, 1844 accepted as Orthorhinus Blyth, 1844 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Orthorhinus Schönherr, 1825 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Orthorhynchus
     Orthorhynchus Swainson, 1820 accepted as Orthorhynchus Swainson, 1820 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Sittidae (Family)
     Orthorhynchus Kirby, 1819 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Belidae (Family)
 Orthorhynchus MacLeay in King, 1826 accepted as Orthorhynchoides Legalov, 2007 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Belidae (Family)
 Orthorhynchus Schoenherr, 1836 accepted as Trypetes Schönherr, 1836 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Orthorhynchus Lacepède, 1801 accepted as Orthorhyncus Lacepède, 1799 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Apodiformes (Order) > Trochilidae (Family)

Orthosaurus
     Orthosaurus Barkas, 1871 † accepted as Orthosaurus Barkas, 1871 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Amphibia (awaiting allocation) (Order) > Amphibia (awaiting allocation) (Family)
     Orthosaurus Geoffroy St Hilaire, 1835 accepted as Orthosaurus Geoffroy St Hilaire, 1835 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)

Orthoserica
     Orthoserica Warren, 1896 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
     Orthoserica Brenske, 1900 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Orthosia
     Orthosia Ochsenheimer, 1816 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
     Orthosia Decaisne in Alph. de Candolle, 1844 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Apocynaceae (Family)
 Orthosia Reinhard, 1944 accepted as Orthosimyia Reinhard, 1944 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Tachinidae (Family)

Orthosoma
     Orthosoma Audinet-Serville, 1832 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Orthosoma Felder, 1874 accepted as Orthosoma Felder, 1874 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
 Orthosoma E.U. Canning, P.J. Wigley & R.J. Baker accepted as Orthosomella E.U. Canning, Wigley & R.J. Barker, 1991 · Protozoa (Kingdom) > Microsporidia (Phylum) > Minisporea (Class) > Microsporida (Order) > Unikaryonidae (Family)

Orthostachys
 Orthostachys Fourreau, 1869 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Lamiaceae (Family)
     Orthostachys (R. Brown) Spach, 1840 accepted as Orthostachys (R. Brown) Spach, 1840 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Boraginales (Order) > Boraginaceae (Family)

Orthostemon
     Orthostemon R. Brown, 1810 accepted as Orthostemon R. Brown, 1810 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Gentianaceae (Family)
 Orthostemon O.C. Berg, 1856 accepted as Acca O.C. Berg, 1856 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Myrtales (Order) > Myrtaceae (Family)

Orthostoma
     Orthostoma Audinet-Serville, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Orthostoma Conrad, 1838 † accepted as Orthostoma Conrad, 1838 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Orthostoma Ehrenberg, 1831 accepted as Orthostoma Ehrenberg, 1831 (unassessed) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Turbellaria (Class) > Turbellaria (awaiting allocation) (Order) > Turbellaria (awaiting allocation) (Family)
 Orthostoma Deshayes, 1853 † accepted as Euactaeonina Wenz, 1947 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Cephalaspidea (Order) > Cephalaspidea (awaiting allocation) (Family)
 Orthostoma Randall, 1840 accepted as Poppiana Bott, 1969 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Trichodactylidae (Family)

Orthostomum
 Orthostomum Grube, 1840 accepted as Orthostomum Grube, 1840 (Misspelling) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Turbellaria (Class) > Turbellaria (awaiting allocation) (Order) > Turbellaria (awaiting allocation) (Family)
     Orthostomum Schmidt, 1852 accepted as Orthostomum Schmidt, 1852 (unassessed) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Turbellaria (Class) > Turbellaria (awaiting allocation) (Order) > Turbellaria (awaiting allocation) (Family)
 Orthostomum Ehrenberg, 1831 accepted as (nomen oblitum) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Platyhelminthes incertae sedis (Class) > Platyhelminthes incertae sedis (Order) > Platyhelminthes incertae sedis (Family)

Orthostylus
     Orthostylus Lutz & Neiva, 1914 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Tabanidae (Family)
     Orthostylus Beck, 1837 accepted as Orthostylus Beck, 1837 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Orthostylus Kittl, 1894 † accepted as Euthystylus Cossmann, 1895 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Neotaenioglossa (Order) > Neotaenioglossa (awaiting allocation) (Family)

Orthotaenia
     Orthotaenia Curtis, 1831 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Tortricidae (Family)
     Orthotaenia Stephens, 1829 accepted as Orthotaenia Curtis, 1831 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Tortricidae (Family)

Orthotheca
     Orthotheca Novák, 1887 † · Animalia (Kingdom) > Hyolitha (Phylum) > (Class) > Orthothecida (Order) > Orthothecida (awaiting allocation) (Family)
     Orthotheca Holm, 1893 † accepted as Orthotheca Holm, 1893 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Orthotheca S.E. Bridel, 1827 accepted as Orthotheca S.E. Bridel, 1827 (unassessed) · Plantae (Kingdom) > Bryophyta (Phylum) > Bryopsida (Class) > Pottiales (Order) > Calymperaceae (Family)
 Orthotheca P. Corsin, 1951 † accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Marattiales (Order) > Marattiales (awaiting allocation) (Family)
 Orthotheca Pichon, 1946 accepted as Cuspidaria A.P. de Candolle, 1838 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Bignoniaceae (Family)

Orthothecium
     Orthothecium W.P. Schimper in Bruch et al., 1851 · Plantae (Kingdom) > Bryophyta (Phylum) > Bryopsida (Class) > Hypnobryales (Order) > Brachytheciaceae (Family)
 Orthothecium H.W. Schott & Endlicher, 1832 accepted as Orthothecium H.W. Schott & Endlicher, 1832 (nomen rejiciendum) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malvales (Order) > Malvaceae (Family)

Orthotomicus
     Orthotomicus Hagedorn, 1910 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Orthotomicus Ferrari, 1867 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Orthotrichia
     Orthotrichia Eaton, 1873 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Trichoptera (Order) > Hydroptilidae (Family)
 Orthotrichia Wehrli in Bang-Haas, 1927 accepted as Autotrichia Prout in Seitz, 1935 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
 Orthotrichia Wingate in Saccardo, 1888 accepted as Clastoderma A. Blytt, 1880 · Protozoa (Kingdom) > Amoebozoa (Phylum) > Myxogastrea (Class) > Echinosteliida (Order) > Clastodermidae (Family)

Orthotrichus
 Orthotrichus Simon, 1889 accepted as Orthotrichus Simon, 1889 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Theraphosidae (Family)
     Orthotrichus Peyron, 1856 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Orthotrochilia
     Orthotrochilia Song, 2003 · Chromista (Kingdom) > Ciliophora (Phylum) > Phyllopharyngea (Class) > Cyrtophorida (Order) > Dysteriidae (Family)
     Orthotrochilia Deroux, 1976 accepted as Orthotrochilia Song, 2003 · Chromista (Kingdom) > Ciliophora (Phylum) > Phyllopharyngea (Class) > Cyrtophorida (Order) > Dysteriidae (Family)

Orthotropis
     Orthotropis Jordan, 1904 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Anthribidae (Family)
     Orthotropis Bentham ex Lindley, 1839 accepted as Orthotropis Bentham ex Lindley, 1839 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)
     Orthotropis Cleve, 1891 · Chromista (Kingdom) > Ochrophyta (Phylum) > Bacillariophyceae (Class) > (Order) > Bacillariophyceae incertae sedis (Family)

Orthotydeus
     Orthotydeus André, 1979 accepted as Tydeus Koch, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Actinedida (Order) > Tydeidae (Family)
 Orthotydeus André, 1980 accepted as Tydeus Koch, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Actinedida (Order) > Tydeidae (Family)

Orthoxiphus
     Orthoxiphus Saussure, 1899 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Podoscirtidae (Family)
 Orthoxiphus Dohrn, 1905 accepted as Habetia Kirby, 1906 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tettigoniidae (Family)

Orthurus
     Orthurus S.V. Juzepczuk in B.K. Schischkin & S.V. Juzepczuk, 1941 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Rosales (Order) > Rosaceae (Family)
     Orthurus Kner, 1866 † · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Amiiformes (Order) > Macrosemiidae (Family)

Orthygia
 Orthygia Mörch, 1853 accepted as Orthygia Mörch, 1853 (Misspelling) · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Veneridae (Family)
 Orthygia Jacoby, 1891 accepted as Pseudorthygia Csiki, 1940 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Ortmannia
     Ortmannia Chiesa, Parma & Camacho, 1995 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Neogastropoda (Order) > Volutidae (Family)
     Ortmannia Schrammen, 1924 † · Animalia (Kingdom) > Porifera (Phylum) > Demospongea (Class) > Astrophorida (Order) > Astrophorida (awaiting allocation) (Family)
 Ortmannia de Loriol, 1906 accepted as Poraniopsis Perrier, 1891 (Synonym according to Fisher (1911)) · Animalia (Kingdom) > Echinodermata (Phylum) > Asteroidea (Class) > Spinulosida (Order) > Poraniidae (Family)
 Ortmannia Rathbun, 1901 accepted as Atyoida Randall, 1840 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Atyidae (Family)
 Ortmannia Opiz, 1834 accepted as Geodorum G. Jackson in H.C. Andrews, 1811 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Ortonella
     Ortonella E.J. Garwood, 1914 † · Bacteria (Kingdom) > Cyanobacteria (Phylum) > Cyanophyceae (Class) > Cyanophyceae (awaiting allocation) (Order) > Porostromata (awaiting allocation) (Family)
     Ortonella Ulrich, 1893 † · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Tuarangiida (Order) > Cyrtodontidae (Family)

Ortonia
     Ortonia Nicholson, 1872 † accepted as Ortonia Nicholson, 1872 † (unassessed) · Animalia (Kingdom) > Annelida (Phylum) > Annelida (awaiting allocation) (Class) > Annelida (awaiting allocation) (Order) > Annelida (awaiting allocation) (Family)
     Ortonia Wood, 1869 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Opiliones (Order) > Stygnidae (Family)
     Ortonia Signoret, 1875 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Margarodidae (Family)

Ortygia
     Ortygia Boie, 1826 accepted as Ortygia Boie, 1826 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Ortygia Pranskevichius, 1972 † accepted as Ortygia Pranskevichius, 1972 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Ostracoda (Class) > Ostracoda (awaiting allocation) (Order) > Ostracoda (awaiting allocation) (Family)
 Ortygia T. Brown, 1827 accepted as Chamelea Mörch, 1853 (Invalid: junior homonym of Ortygia Boie, 1826 [Aves]) · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Veneridae (Family)

Ortygometra
     Ortygometra Leach, 1816 accepted as Ortygometra Leach, 1816 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
 Ortygometra Möhring, 1758 accepted as Ortygometra Möhring, 1758 (Published in a rejected work (ICZN)) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Ortyx
 Ortyx Oken, 1816 accepted as Ortyx Oken, 1816 (Published in a rejected work (ICZN)) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Grallinidae (Family)
 Ortyx Billberg, 1828 accepted as Ortyx Billberg, 1828 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
 Ortyx Chenu & Des Murs in Chenu, 1854 accepted as Ortyx Chenu & Des Murs in Chenu, 1854 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Ortyx Stephens in Shaw, 1819 accepted as Ortyx Stephens in Shaw, 1819 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Galliformes (Order) > Galliformes (awaiting allocation) (Family)

Orus
     Orus Thorell, 1891 accepted as Orus Thorell, 1891 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Arachnida (awaiting allocation) (Order) > Arachnida (awaiting allocation) (Family)
     Orus Casey, 1885 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)

Orvillea
 Orvillea O. Barbosa, 1949 † accepted as · Plantae (Kingdom) > Chlorophyta (Phylum) > Ulvophyceae (Class) > Bryopsidales (Order) > Bryopsidales (awaiting allocation) (Family)
 Orvillea W.H. Lang, 1945 † accepted as Protosalvinia J.W. Dawson, 1886 † (junior synonym, by lectotypification) · Plantae (Kingdom) > Plantae (awaiting allocation) (Phylum) > Plantae (awaiting allocation) (Class) > Plantae (awaiting allocation) (Order) > Plantae incertae sedis (Family)

Oryba
     Oryba Walker, 1856 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Sphingidae (Family)
 Oryba Walker, 1863 accepted as Orybina Snellen, 1895 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Pyralidae (Family)

Orychodes
     Orychodes Pascoe, 1862 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Brentidae (Family)
 Orychodes Kleine, 1921 accepted as Damoisiella Alonso-Zarazaga, Lyal, Bartolozzi & Sforzi in Alonso-Zarazaga & Lyal, 1999 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Brentidae (Family)

Orycteromys
     Orycteromys Pictet, 1842 accepted as Orycteromys Pictet, 1842 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
 Orycteromys Agassiz, 1846 accepted as Orycteromys Agassiz, 1846 (Unjustified (?) emendation) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)

Orycteropus
     Orycteropus G. Cuvier, 1798 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Tubulidentata (Order) > Orycteropodidae (Family)
 Orycteropus Geoffroy, 1796 accepted as Orycteropus G. Cuvier, 1798 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Tubulidentata (Order) > Orycteropodidae (Family)

Orycterotherium
     Orycterotherium Harlan, 1841 † accepted as Orycterotherium Harlan, 1841 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Pilosa (Order) > Megatheriidae (Family)
     Orycterotherium Bronn, 1838 † accepted as Orycterotherium Bronn, 1838 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Cingulata (Order) > Glyptodontidae (Family)

Orycterus
     Orycterus Rafinesque, 1815 accepted as Orycterus Rafinesque, 1815 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
     Orycterus Lesson, 1827 accepted as Orycterus Lesson, 1827 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
 Orycterus Cuvier, 1829 accepted as Bathyergus Illiger, 1811 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Bathyergidae (Family)

Oryctes
     Oryctes Illiger, 1798 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Oryctes S. Watson, 1871 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Solanales (Order) > Solanaceae (Family)

Oryctocephaloides
     Oryctocephaloides Yuan in Zhang, Lu, Zhu, Qian, Lin, Zhou, Zhang & Yuan, 1980 † accepted as Oryctocephaloides Yuan in Zhang, Lu, Zhu, Qian, Lin, Zhou, Zhang & Yuan, 1980 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Trilobita (awaiting allocation) (Order) > Trilobita (awaiting allocation) (Family)
     Oryctocephaloides Chien & Yuan, 1978 † accepted as Oryctocephaloides Chien & Yuan, 1978 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Trilobita (awaiting allocation) (Order) > Trilobita (awaiting allocation) (Family)

Oryctomorphus
     Oryctomorphus Guérin-Ménéville in Duperry, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Oryctomorphus Guérin-Méneville, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Oryctopterus
     Oryctopterus Karny, 1937 accepted as Oryctopterus Karny, 1937 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Orthoptera (awaiting allocation) (Family)
     Oryctopterus Rasnitsyn, 1975 † accepted as Oryctopterus Rasnitsyn, 1975 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)

Oryctopus
     Oryctopus Brunner, 1888 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Stenopelmatidae (Family)
 Oryctopus Rafinesque, 1815 accepted as Orycteropus G. Cuvier, 1798 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Tubulidentata (Order) > Orycteropodidae (Family)

Orygma
     Orygma Meigen, 1830 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Sepsidae (Family)
 Orygma Agassiz, 1846 accepted as Origma Gould, 1838 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Pardalotidae (Family)

Orygocera
     Orygocera Walsingham, 1897 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Oecophoridae (Family)
     Orygocera Schmidt, 1922 accepted as Orygocera Schmidt, 1922 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Orygoceras
 Orygoceras Ruedemann, 1906 † accepted as Rudolfoceras Ulrich, Foerste, Miller & Unklesbay, 1944 † · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Ellesmerocerida (Order) > Protocycloceratidae (Family)
     Orygoceras Brusina, 1882 † · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Hygrophila (Order) > Planorbidae (Family)

Oryssus
 Oryssus Fabricius, 1798 accepted as Orussus Latreille, 1796 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Orussidae (Family)
 Oryssus Hustache, 1949 accepted as Orissus Pascoe, 1889 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Orythia
     Orythia Péron & Lesueur, 1810 accepted as Orythia Péron & Lesueur, 1810 (unassessed) · Animalia (Kingdom) > Cnidaria (Phylum) > Hydrozoa (Class) > Hydrozoa (awaiting allocation) (Order) > Hydrozoa (awaiting allocation) (Family)
     Orythia Lamarck, 1816 accepted as Orythia Lamarck, 1816 (unassessed) · Animalia (Kingdom) > Cnidaria (Phylum) > Scyphozoa (Class) > Scyphozoa (awaiting allocation) (Order) > Scyphozoa (awaiting allocation) (Family)
 Orythia Johnston, 1837 accepted as Phoxichilidium Milne Edwards, 1840 · Animalia (Kingdom) > Arthropoda (Phylum) > Pycnogonida (Class) > Pantopoda (Order) > Phoxichilidiidae (Family)

Orythyia
 Orythyia Goodsir, 1842 accepted as Phoxichilidium Milne Edwards, 1840 · Animalia (Kingdom) > Arthropoda (Phylum) > Pycnogonida (Class) > Pantopoda (Order) > Phoxichilidiidae (Family)
 Orythyia Latreille, 1804 accepted as Orithyia Fabricius, 1798 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Orithyiidae (Family)

Oryx
     Oryx Blainville, 1816 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Artiodactyla (Order) > Bovidae (Family)
     Oryx Lesson, 1831 accepted as Oryx Lesson, 1831 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Oryx Guérin-Ménéville, 1838 accepted as Oryx Guérin-Ménéville, 1838 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Oryx Oken, 1816 accepted as Oryx Oken, 1816 (Published in a rejected work (ICZN)) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Cetacea (Order) > Delphinidae (Family)
 Oryx Tournier, 1874 accepted as Paroryx Reitter, 1913 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Oryzaria
 Oryzaria Agassiz, 1846 accepted as Oryzaria Agassiz, 1846 (Unjustified (?) emendation) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)
 Oryzaria Defrance, 1825 † accepted as Alveolina d'Orbigny, 1826 † (Nom rejected ICZN ZN 2356) · Chromista (Kingdom) > Retaria (Phylum) > Tubothalamea (Class) > Miliolida (Order) > Alveolinidae (Family)

Oryzivora
     Oryzivora Agassiz, 1846 accepted as Oryzivora Agassiz, 1846 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Oryzivora Horsfield & Moore, 1858 accepted as Oryzivora Horsfield & Moore, 1858 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Orzeliscus
     Orzeliscus du Bois-Reymond Marcus, 1952 · Animalia (Kingdom) > Tardigrada (Phylum) > Heterotardigrada (Class) > Arthrotardigrada (Order) > Orzeliscidae (Family)
     Orzeliscus du Bois-Reymond Marcus, 1952 · Animalia (Kingdom) > Tardigrada (Phylum) > Heterotardigrada (Class) > Arthrotardigrada (Order) > Halechiniscidae (Family)

Osa
     Osa Paramonov, 1958 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Pyrgotidae (Family)
     Osa A. Aiello, 1979 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Rubiaceae (Family)

Osaka
     Osaka Kondô, 1936 accepted as Osaka Kondô, 1936 (unassessed) · Animalia (Kingdom) > Annelida (Phylum) > Oligochaeta (Class) > Oligochaeta (awaiting allocation) (Order) > Oligochaeta (awaiting allocation) (Family)
     Osaka Distant, 1909 accepted as Osaka Distant, 1909 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Nogodinidae (Family)

Osbeckia
     Osbeckia Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Myrtales (Order) > Melastomataceae (Family)
 Osbeckia Jordan & Evermann, 1896 accepted as Aluterus Cloquet, 1816 (synonym) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Tetraodontiformes (Order) > Monacanthidae (Family)

Osbornia
     Osbornia F. von Mueller, 1862 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Myrtales (Order) > Myrtaceae (Family)
     Osbornia Ball, 1910 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Issidae (Family)

Osca
     Osca Walker, 1863 accepted as Osca Walker, 1863 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Osca Stål, 1870 accepted as Osca Stål, 1870 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Osca Walker in Saunders, 1850 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Tabanidae (Family)

Oscabrella
     Oscabrella Broderip, 1836 · Animalia (Kingdom) > Mollusca (Phylum) > Polyplacophora (Class) > Chitonida (Order) > Cryptoplacidae (Family)
     Oscabrella Partington, 1835 accepted as Oscabrella Partington, 1835 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Oscanius
     Oscanius Winckworth, 1932 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Pleurobranchomorpha (Order) > Pleurobranchidae (Family)
 Oscanius Leach in Gray, 1847 accepted as Pleurobranchus Cuvier, 1804 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Pleurobranchomorpha (Order) > Pleurobranchidae (Family)

Oscaria
     Oscaria Lilja, 1839 accepted as Oscaria Lilja, 1839 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Ericales (Order) > Primulaceae (Family)
     Oscaria Gray, 1873 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Testudines (Order) > Trionychidae (Family)
 Oscaria Vosmaer, 1881 accepted as Oscarella Vosmaer in Bronn, 1884 (preoccupied) · Animalia (Kingdom) > Porifera (Phylum) > Demospongea (Class) > Homosclerophorida (Order) > Oscarellidae (Family)

Osceola
     Osceola Baird & Girard, 1853 accepted as Osceola Baird & Girard, 1853 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)
     Osceola Hulst in Smith, 1891 accepted as Osceola Hulst in Smith, 1891 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)

Oscillaria
     Oscillaria C. Pollini, 1816 · Chromista (Kingdom) > Ochrophyta (Phylum) > Bacillariophyceae (Class) > (Order) > Bacillariophyceae incertae sedis (Family)
 Oscillaria Laveran in Richard, 1883 accepted as Plasmodium Marchiafava & Celli, 1885 · Chromista (Kingdom) > Miozoa (Phylum) > Coccidiomorphea (Class) > Haemosporida (Order) > Plasmodiidae (Family)

Osculatia
     Osculatia De Notaris, 1859 accepted as Osculatia De Notaris, 1859 (unassessed) · Plantae (Kingdom) > Bryophyta (Phylum) > Bryopsida (Class) > Bryales (Order) > Bryaceae (Family)
     Osculatia Bonaparte, 1855 accepted as Osculatia Bonaparte, 1855 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Columbiformes (Order) > Columbidae (Family)

Osdara
     Osdara Walker, 1858 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)
 Osdara Walker, 1865 accepted as Radosa Nye, 1975 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)

Osdaroides
     Osdaroides Kaszab, 1979 accepted as Osdaroides Kaszab, 1979 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Osdaroides Kaszab, 1980 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Oshia
     Oshia Sytchevskaya, 1999 † accepted as Oshia Sytchevskaya, 1999 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Scanilepiformes (Order) > Evenkiidae (Family)
 Oshia accepted as Oschia Sæther, 1983 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Chironomidae (Family)

Osimus
     Osimus Steven or Fischer Waldheim, 1829 accepted as Osimus Steven or Fischer Waldheim, 1829 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
     Osimus Motschulsky, 1850 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Oskampia
     Oskampia Moench, 1794 accepted as Oskampia Moench, 1794 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Boraginales (Order) > Boraginaceae (Family)
 Oskampia Rafinesque, 1838 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Boraginales (Order) > Boraginaceae (Family)
 Oskampia Baillon, 1890 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Boraginales (Order) > Boraginaceae (Family)

Osmerus
     Osmerus Forsskål, 1775 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Osmeriformes (Order) > Osmeridae (Family)
     Osmerus Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Osmeriformes (Order) > Osmeridae (Family)
 Osmerus Lacepède, 1803 accepted as Osmerus Linnaeus, 1758 (synonym) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Osmeriformes (Order) > Osmeridae (Family)

Osmia
     Osmia Panzer, 1806 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Megachilidae (Family)
     Osmia C.H. Schultz-Bipontinus, 1866 accepted as Osmia C.H. Schultz-Bipontinus, 1866 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)

Osmotherium
     Osmotherium Cope, 1896 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Mustelidae (Family)
     Osmotherium Cope, 1896 † accepted as Osmotherium Cope, 1896 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Mustelidae (Family)

Osmundites
     Osmundites Jaeger, 1827 † accepted as Osmundites Jaeger, 1827 † (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Cycadopsida (Class) > Cycadales (Order) > Cycadales (awaiting allocation) (Family)
 Osmundites F.J.A.N. Unger, 1854 † accepted as Osmundacaulis C.N. Miller, 1967 † (junior homonym) · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Osmundales (Order) > Osmundaceae (Family)

Osmylus
     Osmylus Latreille, 1802 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Neuroptera (Order) > Osmylidae (Family)
     Osmylus Blainville, 1825 accepted as Osmylus Blainville, 1825 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Osorius
     Osorius Berthold in Latreille, 1827 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
     Osorius Guérin-Méneville, 1829 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
 Osorius Latreille, 1825 accepted as Osorius Guérin-Méneville, 1829 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
     Osorius Dejean, 1821 accepted as Osorius Guérin-Méneville, 1829 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)

Osphromenus
 Osphromenus Günther, 1861 accepted as Osphronemus Lacepède, 1801 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Osphronemidae (Family)
 Osphromenus Cuvier, 1829 accepted as Osphronemus Lacepède, 1801 (misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Osphronemidae (Family)

Ossa
     Ossa Giglio-Tos, 1894 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Ommexechidae (Family)
 Ossa Motschoulsky, 1863 accepted as Tambinia Stål, 1859 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Tropiduchidae (Family)

Ossiannilssonia
     Ossiannilssonia Hille Ris Lambers, 1952 accepted as Ossiannilssonia Hille Ris Lambers, 1952 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
 Ossiannilssonia Young & Christian in Young, 1952 accepted as Ossiannilssonola Christian, 1953 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Cicadellidae (Family)

Ossiculum
     Ossiculum P.J. Cribb & F.M. van der Laan in F.M. van der Laan & P.J. Cribb, 1986 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
     Ossiculum Bigsby, 1868 accepted as Ossiculum Bigsby, 1868 · Animalia (Kingdom) > Cnidaria (Phylum) > Cnidaria (awaiting allocation) (Class) > Cnidaria (awaiting allocation) (Order) > Cnidaria (awaiting allocation) (Family)

Ossifraga
     Ossifraga Wood, 1835 accepted as Ossifraga Wood, 1835 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
 Ossifraga Rumph. accepted as Euphorbia Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malpighiales (Order) > Euphorbiaceae (Family)
 Ossifraga Hombron & Jacquinot, 1844 accepted as Macronectes Richmond, 1905 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Procellariiformes (Order) > Procellariidae (Family)

Ostenia
     Ostenia Hutton, 1901 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Dolichopodidae (Family)
 Ostenia Buchenau, 1906 accepted as Hydrocleys L.C. Richard, 1815 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Alismatales (Order) > Alismataceae (Family)
 Ostenia Arduini, Pinna & Terazzi, 1980 † accepted as Ostenocaris Arduini, Pinna & Teruzzi, 1984 † · Animalia (Kingdom) > Arthropoda (Phylum) > Conchyliocarida (Class) > Conchyliocarida (awaiting allocation) (Order) > Conchyliocarida (awaiting allocation) (Family)

Osteoborus
     Osteoborus Stirton & Vanderhoof, 1933 † accepted as Osteoborus Stirton & Vanderhoof, 1933 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Canidae (Family)
 Osteoborus Gregory, 1942 † accepted as Osteoborus Stirton & Vanderhoof, 1933 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Canidae (Family)

Osteocephalus
     Osteocephalus Steindachner, 1862 · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Anura (Order) > Hylidae (Family)
     Osteocephalus Fitzinger, 1843 accepted as Osteocephalus Steindachner, 1862 · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Anura (Order) > Hylidae (Family)

Osteodes
     Osteodes Guenée, 1857 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
     Osteodes Paetel, 1887 accepted as Osteodes Paetel, 1887 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Neogastropoda (Order) > Melongenidae (Family)
 Osteodes Conrad, 1855 accepted as Balanophyllia Wood, 1844 · Animalia (Kingdom) > Cnidaria (Phylum) > Anthozoa (Class) > Scleractinia (Order) > Dendrophylliidae (Family)

Osteoglossum
     Osteoglossum Cuvier, 1829 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Osteoglossiformes (Order) > Osteoglossidae (Family)
 Osteoglossum Basilewsky, 1855 accepted as Coilia Gray, 1830 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Clupeiformes (Order) > Engraulidae (Family)
 Osteoglossum Agassiz in Spix & Agassiz, 1829 accepted as Osteoglossum Cuvier, 1829 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Osteoglossiformes (Order) > Osteoglossidae (Family)

Osteophorus
     Osteophorus Meyer, 1857 † accepted as Osteophorus Meyer, 1857 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Temnospondyli (Order) > Eryopidae (Family)
     Osteophorus Philippi, 1893 accepted as Osteophorus Philippi, 1893 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Osteorophea
     Osteorophea Hodgson, 1844 accepted as Osteorophea Hodgson, 1844 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Osteorophea Gray in J.L.G. Gray, 1846 accepted as Osteorophea Gray in J.L.G. Gray, 1846 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Ostichthys
     Ostichthys Cuvier in Cuvier & Valenciennes, 1829 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Beryciformes (Order) > Holocentridae (Family)
 Ostichthys Jordan & Evermann, 1896 accepted as Ostichthys Cuvier in Cuvier & Valenciennes, 1829 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Beryciformes (Order) > Holocentridae (Family)

Ostodes
     Ostodes Gould, 1862 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Architaenioglossa (Order) > Neocyclotidae (Family)
     Ostodes Blume, 1826 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malpighiales (Order) > Euphorbiaceae (Family)

Ostracion
     Ostracion Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Tetraodontiformes (Order) > Ostraciidae (Family)
     Ostracion Walch accepted as Ostracion Walch (unassessed) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinodermata (awaiting allocation) (Class) > Echinodermata (awaiting allocation) (Order) > Echinodermata (awaiting allocation) (Family)

Ostracoderma
 Ostracoderma E.M. Fries, 1829 accepted as · Fungi (Kingdom) > Ascomycota (Phylum) > Pezizomycetes (Class) > Pezizales (Order) > Pezizaceae (Family)
     Ostracoderma E.M. Fries, 1825 · Fungi (Kingdom) > Ascomycota (Phylum) > Pezizomycetes (Class) > Pezizales (Order) > Pezizaceae (Family)

Ostralegus
 Ostralegus Lesson, 1839 accepted as Ostralegus Lesson, 1839 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
 Ostralegus Reichenbach, 1853 accepted as Haematopus Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Charadriiformes (Order) > Charadriidae (Family)

Ostreola
     Ostreola G.D. Darker, 1963 · Fungi (Kingdom) > Ascomycota (Phylum) > Dothideomycetes (Class) > Mytilinidiales (Order) > Mytilinidiaceae (Family)
 Ostreola Monterosato, 1884 accepted as Ostrea Linnaeus, 1758 · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Ostreida (Order) > Ostreidae (Family)

Ostrya
 Ostrya J. Hill, 1757 accepted as Ostrya J. Hill, 1757 (nomen rejiciendum) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fagales (Order) > Betulaceae (Family)
     Ostrya Scopoli, 1760 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fagales (Order) > Betulaceae (Family)

Oswaldia
     Oswaldia Robineau-Desvoidy, 1863 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Tachinidae (Family)
 Oswaldia Rangel, 1921 accepted as Apiosphaeria F. von Höhnel, 1909 · Fungi (Kingdom) > Ascomycota (Phylum) > Sordariomycetes (Class) > Phyllachorales (Order) > Phyllachoraceae (Family)

Otagoa
     Otagoa Forster, 1970 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Desidae (Family)
     Otagoa Lloyd, 1922 · Fungi (Kingdom) > Fungi (awaiting allocation) (Phylum) > Fungi (awaiting allocation) (Class) > Fungi (awaiting allocation) (Order) > Fungi (awaiting allocation) (Family)

Otaria
     Otaria Zhdanko, 1984 accepted as Otaria Zhdanko, 1984 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lycaenidae (Family)
     Otaria Péron in Péron & Lesueur, 1816 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Otariidae (Family)
     Otaria Kunth ex G. Don, 1837 accepted as Otaria Kunth ex G. Don, 1837 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Apocynaceae (Family)
     Otaria Shaw, 1800 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Otariidae (Family)

Otariella
     Otariella Waterhouse, 1978 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Strophomenata (Class) > Strophomenatida (Order) > Strophomenida (awaiting allocation) (Family)
     Otariella Popov & Holmer, 1994 † accepted as Otariella Popov & Holmer, 1994 † (unassessed) · Animalia (Kingdom) > Brachiopoda (Phylum) > Brachiopoda (awaiting allocation) (Class) > Brachiopoda (awaiting allocation) (Order) > Brachiopoda (awaiting allocation) (Family)

Otarionella
     Otarionella Koroleva, 1977 † accepted as Otarionella Koroleva, 1977 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Trilobita (awaiting allocation) (Order) > Trilobita (awaiting allocation) (Family)
     Otarionella Weyber, 1965 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Proetida (Order) > Proetida (awaiting allocation) (Family)

Otavia
 Otavia Risso, 1826 accepted as Clanculus Montfort, 1810 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Vetigastropoda (Order) > Trochidae (Family)
     Otavia Brain, Prave, Hoffmann, Fallick, Botha, Herd, Sturrock, Young, Condon & Allison, 2012 † · Animalia (Kingdom) > Animalia incertae sedis (Phylum) > (Class) > (Order) > (Family)

Othius
     Othius Stephens, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
 Othius Stephens, 1829 accepted as Othius Stephens, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)

Otho
     Otho Lacordaire, 1857 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Eucnemidae (Family)
 Otho Kiesenwetter in Erichson, 1858 accepted as Otho Lacordaire, 1857 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Eucnemidae (Family)

Othonia
 Othonia Johnston, 1835 accepted as Fabricia Blainville, 1828 (discarded replacement name) · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Sabellida (Order) > Fabriciidae (Family)
 Othonia Bell, 1836 accepted as Pitho Bell, 1836 (name pre-occupied by Othonia Johnston, 1835 [Polychaeta]) · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Majidae (Family)

Otideres
     Otideres Dejean, 1835 accepted as Cylydrorhinus Guérin-Ménéville in Duperry, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Otideres Chevrolat, 1847 accepted as Cylydrorhinus Guérin-Ménéville in Duperry, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
     Otideres Dejean, 1836 accepted as Cylydrorhinus Guérin-Ménéville in Duperry, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Otina
     Otina Gray, 1847 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Eupulmonata incertae sedis (Order) > Otinidae (Family)
     Otina Whitfield, 1865 accepted as Otina Whitfield, 1865 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Otinia
     Otinia Antoine, 1942 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)
 Otinia Sowerby, 1923 accepted as Otina Gray, 1847 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Eupulmonata incertae sedis (Order) > Otinidae (Family)

Otiophora
     Otiophora Turner, 1908 accepted as Otiophora Turner, 1908 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Otiophora Zuccarini, 1832 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Rubiaceae (Family)

Otiorcossonus
 Otiorcossonus Voss, 1934 accepted as Cossonus Schellenberg, 1798 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Otiorcossonus Voss, 1956 accepted as Cossonus Schellenberg, 1798 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Otiorrhynchites
     Otiorrhynchites Haupt, 1956 † · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera incertae sedis (Family)
 Otiorrhynchites Handlirsch, 1925 † accepted as Otiorhynchites Fritsch, 1882 † · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Otites
     Otites Latreille, 1804 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Otitidae (Family)
     Otites Adanson, 1763 accepted as Otites Adanson, 1763 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Caryophyllales (Order) > Caryophyllaceae (Family)

Otoclinus
     Otoclinus Brenske, 1896 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Otoclinus Gervais, 1845 accepted as Galago Geoffroy, 1796 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Primates (Order) > Galagonidae (Family)

Otocolobus
 Otocolobus Severtzov, 1858 accepted as Felis Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Felidae (Family)
 Otocolobus Brandt, 1844 accepted as Spermophilus Cuvier, 1824 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Sciuridae (Family)
 Otocolobus Brandt, 1842 accepted as Felis Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Felidae (Family)

Otolelus
     Otolelus Klinger, 2000 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Aderidae (Family)
 Otolelus Burakowski, Mroczkowski & Stefańska, 1987 accepted as Otolelus Klinger, 2000 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Aderidae (Family)

Otolepis
     Otolepis Strauch, 1866 accepted as Otolepis Strauch, 1866 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)
     Otolepis Turczaninow, 1848 accepted as Otolepis Turczaninow, 1848 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Sapindales (Order) > Sapindaceae (Family)

Otolicnus
     Otolicnus Fischer, 1813 accepted as Otolicnus Fischer, 1813 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Canidae (Family)
 Otolicnus Illiger, 1811 accepted as Galago Geoffroy, 1796 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Primates (Order) > Galagonidae (Family)

Otolithus
     Otolithus Koken, 1884 † accepted as Otolithus Koken, 1884 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Pisces (awaiting allocation) (Class) > Pisces (awaiting allocation) (Order) > Pisces (awaiting allocation) (Family)
 Otolithus Cuvier, 1829 accepted as Otolithes Oken, 1817 (misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Sciaenidae (Family)

Otomyces
     Otomyces E.H. Hallier, 1869 · Fungi (Kingdom) > Ascomycota (Phylum) > Ascomycota incertae sedis (Class) > Ascomycota incertae sedis (Order) > Ascomycota incertae sedis (Family)
 Otomyces Wreden, 1874 accepted as Aspergillus Micheli ex Link, 1809 · Fungi (Kingdom) > Ascomycota (Phylum) > Eurotiomycetes (Class) > Eurotiales (Order) > Trichocomaceae (Family)

Otomys
     Otomys Cuvier, 1823 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Muridae (Family)
 Otomys Smith, 1834 accepted as Malacothrix Wagner in Schreber, 1843 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Rodentia (Order) > Nesomyidae (Family)

Otopetalum
     Otopetalum Miquel, 1857 accepted as Otopetalum Miquel, 1857 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Apocynaceae (Family)
 Otopetalum Lehmann & Kraenzlin, 1899 accepted as Pleurothallis R. Brown in W.T. Aiton, 1813 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)

Otopsis
     Otopsis Ditlevsen, 1917 · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Phyllodocida (Order) > Pilargidae (Family)
     Otopsis Rafinesque, 1815 accepted as Otopsis Rafinesque, 1815 · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)

Otopteris
     Otopteris Lindley & W. Hutton, 1834 † accepted as Otopteris Lindley & W. Hutton, 1834 † (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Cycadopsida (Class) > Cycadales (Order) > Cycadales (awaiting allocation) (Family)
 Otopteris J.J.D. Sauveur, 1848 † accepted as · Plantae (Kingdom) > Plantae (awaiting allocation) (Phylum) > Plantae (awaiting allocation) (Class) > Plantae (awaiting allocation) (Order) > Plantae (awaiting allocation) (Family)

Otopterus
 Otopterus Lydekker in Flower & Lydekker, 1891 accepted as Macrotus Gray, 1843 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Chiroptera (Order) > Phyllostomidae (Family)
 Otopterus Sokolov, 1973 accepted as Otopteropus Kock, 1969 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Chiroptera (Order) > Pteropodidae (Family)

Otosema
     Otosema Hübner, 1823 accepted as Otosema Hübner, 1823 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
 Otosema Bentham in Miquel, 1852 accepted as Millettia R. Wight & Arnott, 1834 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)

Otosphinctes
     Otosphinctes Beznosov in Benzosov & Mikhaylova, 1981 † accepted as Otosphinctes Beznosov in Benzosov & Mikhaylova, 1981 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Cephalopoda (awaiting allocation) (Order) > Cephalopoda (awaiting allocation) (Family)
     Otosphinctes Buckman, 1926 † accepted as Otosphinctes Buckman, 1926 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Otostylis
     Otostylis Schlechter, 1918 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Orchidaceae (Family)
     Otostylis Gloger, 1841 accepted as Otostylis Gloger, 1841 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)

Ototettix
     Ototettix Oshanin, 1913 accepted as Ototettix Oshanin, 1913 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Ototettix Oshanin, 1912 accepted as Ototettix Oshanin, 1912 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)

Ottelia
     Ottelia Persoon, 1805 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Alismatales (Order) > Hydrocharitaceae (Family)
 Ottelia R.A. Hedwig, 1806 accepted as Stratiotes Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Alismatales (Order) > Hydrocharitaceae (Family)

Ottonia
     Ottonia Simroth, 1920 accepted as Ottonia Simroth, 1920 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
 Ottonia J. Schiller, 1925 accepted as · Protozoa (Kingdom) > Euglenozoa (Phylum) > Euglenophyceae (Class) > Euglenophyceae (awaiting allocation) (Order) > Euglenophyceae (awaiting allocation) (Family)
 Ottonia K.P.J. Sprengel, 1820 accepted as Piper Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Piperales (Order) > Piperaceae (Family)
 Ottonia Kramer, 1877 accepted as Camerotrombidium Thor, 1936 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Actinedida (Order) > Microtrombidiidae (Family)
 Ottonia Gistl, 1848 accepted as Pitho Bell, 1836 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Majidae (Family)
 Ottonia (Malm, 1874) accepted as Malmiana (Strand, 1942) (preoccupied) · Animalia (Kingdom) > Annelida (Phylum) > Hirudinea (Class) > Rhynchobdellida (Order) > Piscicolidae (Family)

Otus
     Otus Pennant, 1769 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Strigiformes (Order) > Strigidae (Family)
     Otus Gray, 1871 accepted as Otus Gray, 1871 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Ciconiiformes (Order) > Ciconiiformes (awaiting allocation) (Family)
     Otus Hübner, 1819 accepted as Otus Hübner, 1819 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
 Otus Bate, 1862 accepted as Odius Liljeborg, 1865 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Amphipoda (Order) > Odiidae (Family)
     Otus Dejean, 1821 accepted as Brachyderes Schönherr, 1823 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Otus Cuvier, 1800 accepted as Otis Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Gruiformes (Order) > Otididae (Family)
 Otus Risso, 1826 accepted as Ficus Röding, 1798 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Littorinimorpha (Order) > Ficidae (Family)

Otwayia
     Otwayia Richards, 1973 accepted as Otwayia Richards, 1973 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Diptera (awaiting allocation) (Family)
     Otwayia Pole, 2000 † accepted as Otwayia Pole, 2000 † (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Pinopsida (Class) > Pinales (Order) > Cheirolepidiaceae (Family)

Oudemansia
     Oudemansia Schött, 1893 · Animalia (Kingdom) > Arthropoda (Phylum) > Collembola (Class) > Poduromorpha (Order) > Hypogastruridae (Family)
     Oudemansia Miquel, 1854 accepted as Oudemansia Miquel, 1854 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malvales (Order) > Malvaceae (Family)
 Oudemansia Spegazzini, 1880 accepted as Oudemansiella Spegazzini, 1881 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Agaricales (Order) > Physalacriaceae (Family)

Oudemansiella
     Oudemansiella Spegazzini, 1881 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Agaricales (Order) > Physalacriaceae (Family)
     Oudemansiella Fonseca, 1948 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Mesostigmata (Order) > Macronyssidae (Family)

Oudhia
     Oudhia Gupta, 1955 accepted as Oudhia Gupta, 1955 (unassessed) · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Trematoda (awaiting allocation) (Order) > Trematoda (awaiting allocation) (Family)
     Oudhia Dayal & Gupta, 1953 · Animalia (Kingdom) > Platyhelminthes (Phylum) > Trematoda (Class) > Plagiorchiida (Order) > Cephalogonimidae (Family)

Ouijjania
     Ouijjania Hupé, 1953 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Ptychopariida (Order) > Ptychopariida (awaiting allocation) (Family)
     Ouijjania Hupé in Piveteau, 1953 † accepted as Ouijjania Hupé, 1953 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Ptychopariida (Order) > Ptychopariida (awaiting allocation) (Family)

Ouracoccus
     Ouracoccus (A.H. Hassall) J. Lindley, 1846 accepted as Ouracoccus (A.H. Hassall) J. Lindley, 1846 (unassessed) · Plantae (Kingdom) > Chlorophyta (Phylum) > Chlorophyceae (Class) > Chlamydomonadales (Order) > Coccomyxaceae (Family)
 Ouracoccus Loeblich Jr. & Loeblich III, 1966 accepted as Rufusiella A.R. Loeblich III in T. Christensen, 1978 · Chromista (Kingdom) > Miozoa (Phylum) > Dinophyceae (Class) > Phytodiniales (Order) > Dinocloniaceae (Family)

Ourococcus
     Ourococcus Fuller, 1899 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Eriococcidae (Family)
     Ourococcus Grobéty, 1909 · Plantae (Kingdom) > Chlorophyta (Phylum) > Chlorophyceae (Class) > Chlamydomonadales (Order) > Coccomyxaceae (Family)
     Ourococcus Fuller, 1897 accepted as Ourococcus Fuller, 1899 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Eriococcidae (Family)

Oustaletia
     Oustaletia Brongniart, 1885 † accepted as Oustaletia Brongniart, 1885 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Palaeodictyoptera (Order) > Palaeodictyoptera (awaiting allocation) (Family)
     Oustaletia Trouessart, 1885 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Astigmata (Order) > Vexillariidae (Family)

Ova
     Ova Gray, 1825 · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Spatangoida (Order) > Schizasteridae (Family)
     Ova Pomel, 1887 † accepted as Ova Pomel, 1887 † (unassessed) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinodermata (awaiting allocation) (Class) > Echinodermata (awaiting allocation) (Order) > Echinodermata (awaiting allocation) (Family)
 Ova † accepted as Ovum A. Eisenack, 1931 † · Protozoa (Kingdom) > Acritarcha (Phylum) > Acritarcha (awaiting allocation) (Class) > Acritarcha (awaiting allocation) (Order) > Acritarcha (awaiting allocation) (Family)

Ovacarus
     Ovacarus Stannard & Vaishampayan, 1971 † · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Actinedida (Order) > Podapolipidae (Family)
 Ovacarus Gaud & Atyeo, 1975 † accepted as Apionacarus Gaud & Atyeo, 1977 † · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Astigmata (Order) > Apionacaridae (Family)

Ovalia
     Ovalia González-Sponga, 1999 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Opiliones (Order) > Zalmoxidae (Family)
     Ovalia Latreille in Cuvier, 1833 accepted as Ovalia Latreille in Cuvier, 1833 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Crustacea (awaiting allocation) (Class) > Crustacea (awaiting allocation) (Order) > Crustacea (awaiting allocation) (Family)
 Ovalia Nalivkin, 1937 † accepted as Brachythyris M'Coy in Griffith, 1844 † · Animalia (Kingdom) > Brachiopoda (Phylum) > Rhynchonellata (Class) > Spiriferida (Order) > Brachythyrididae (Family)

Ovalveolina
     Ovalveolina Reichel, 1935 † accepted as Ovalveolina Reichel, 1935 † (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)
     Ovalveolina Reichel, 1936 † · Chromista (Kingdom) > Retaria (Phylum) > Tubothalamea (Class) > Miliolida (Order) > Alveolinidae (Family)

Ovatella
     Ovatella Bivona-Bernardi, 1832 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Ellobiida (Order) > Ellobiidae (Family)
     Ovatella Solovieva, 1996 † accepted as Ovatella Solovieva, 1996 † (unassessed) · Chromista (Kingdom) > Retaria (Phylum) > Foraminifera incertae sedis (Class) > Foraminifera (awaiting allocation) (Order) > Foraminifera (awaiting allocation) (Family)

Overlaetia
     Overlaetia Kiriakoff, 1954 accepted as Overlaetia Kiriakoff, 1954 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Lepidoptera (awaiting allocation) (Family)
     Overlaetia Schouteden, 1932 accepted as Overlaetia Schouteden, 1932 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Overlaetia Pic, 1937 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Ovidia
 Ovidia Rafinesque, 1837 accepted as Ovidia Rafinesque, 1837 (nomen rejiciendum) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Commelinales (Order) > Commelinaceae (Family)
     Ovidia Girault, 1924 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Torymidae (Family)
     Ovidia Meisner in Alph. de Candolle, 1857 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Malvales (Order) > Thymelaeaceae (Family)

Ovieda
 Ovieda K.P.J. Sprengel, 1817 accepted as · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asparagales (Order) > Iridaceae (Family)
     Ovieda Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Lamiales (Order) > Lamiaceae (Family)

Ovoides
     Ovoides Anonymous, 1798 accepted as Ovoides Anonymous, 1798 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Tetraodontiformes (Order) > Tetraodontidae (Family)
     Ovoides Cuvier, 1800 accepted as Ovoides Anonymous, 1798 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Tetraodontiformes (Order) > Tetraodontidae (Family)
 Ovoides Lacepède, 1798 accepted as Ovoides Anonymous, 1798 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Tetraodontiformes (Order) > Tetraodontidae (Family)
 Ovoides Duméril, 1805 accepted as Ovoides Anonymous, 1798 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Tetraodontiformes (Order) > Tetraodontidae (Family)

Ovoplasma
     Ovoplasma Raadt, 1913 accepted as Ovoplasma Raadt, 1913 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)
     Ovoplasma Marzinkowsky & Bogrow, 1904 accepted as Ovoplasma Marzinkowsky & Bogrow, 1904 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)

Ovula
     Ovula Bruguière, 1789 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Littorinimorpha (Order) > Ovulidae (Family)
     Ovula Hübner, 1810 accepted as Ovula Hübner, 1810 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Ovularia
 Ovularia Link, 1830 accepted as Ovula Bruguière, 1789 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Littorinimorpha (Order) > Ovulidae (Family)
 Ovularia P.A. Saccardo, 1880 accepted as Ramularia Unger, 1833 · Fungi (Kingdom) > Ascomycota (Phylum) > Dothideomycetes (Class) > Capnodiales (Order) > Mycosphaerellaceae (Family)

Ovulechinus
     Ovulechinus Lambert, 1918 † accepted as Ovulechinus Lambert, 1920 † · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Oligopygoida (Order) > Oligopygoida (awaiting allocation) (Family)
     Ovulechinus Lambert, 1920 † · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Euechinoidea incertae sedis (Order) > Pygaulidae (Family)

Ovulina
     Ovulina Gruber, 1884 accepted as Ovulina Gruber, 1884 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)
 Ovulina Schultze, 1854 accepted as Marsupulina Rhumbler, 1904 · Chromista (Kingdom) > Retaria (Phylum) > Monothalamea (Class) > Allogromiida (Order) > Allogromiidae (Family)
 Ovulina Ehrenberg, 1845 accepted as Oolina d'Orbigny, 1839 (Opinion of Loeblich & Tappan, 1987) · Chromista (Kingdom) > Retaria (Phylum) > Globothalamea (Class) > Lagenida (Order) > Ellipsolagenidae (Family)
 Ovulina Anderson, Rogerson & Hannah, 1996 accepted as Ovulinata Anderson, Rogerson & Hannah, 1997 (junior homonym) · Chromista (Kingdom) > Cercozoa (Phylum) > Imbricatea (Class) > Euglyphida (Order) > Paulinellidae (Family)

Ovulites
     Ovulites J.B. de Lamarck ex J.V.F. Lamouroux, 1821 † accepted as Ovulites J.B. de Lamarck ex J.V.F. Lamouroux, 1821 † (unassessed) · Plantae (Kingdom) > Chlorophyta (Phylum) > Ulvophyceae (Class) > Bryopsidales (Order) > Codiaceae (Family)
 Ovulites C.S. Rafinesque, 1815 accepted as Ovulites C.S. Rafinesque, 1815 (Misspelling) · Plantae (Kingdom) > Algae (awaiting allocation) (Phylum) > Algae (awaiting allocation) (Class) > Algae (awaiting allocation) (Order) > Algae (awaiting allocation) (Family)

Ovulum
     Ovulum T.V. Jankauskas, 1975 † · Protozoa (Kingdom) > Acritarcha (Phylum) > Acritarcha (awaiting allocation) (Class) > Acritarcha (awaiting allocation) (Order) > Acritarcha (awaiting allocation) (Family)
 Ovulum G. B. Sowerby I, 1828 accepted as Ovula Bruguière, 1789 (unjustified emendation) · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Littorinimorpha (Order) > Ovulidae (Family)

Ovum
     Ovum A. Eisenack, 1931 † · Protozoa (Kingdom) > Acritarcha (Phylum) > Acritarcha (awaiting allocation) (Class) > Acritarcha (awaiting allocation) (Order) > Acritarcha (awaiting allocation) (Family)
 Ovum Blainville, 1830 accepted as Ovum Blainville, 1830 (Misspelling) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Spatangoida (Order) > Schizasteridae (Family)
     Ovum Bloch & Schneider, 1801 accepted as Ovum Bloch & Schneider, 1801 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Tetraodontiformes (Order) > Tetraodontidae (Family)
     Ovum de Wever, 1982 † accepted as Ovum de Wever, 1982 † (unassessed) · Protozoa (Kingdom) > (Phylum) > (Class) > Sarcomastigota (awaiting allocation) (Order) > Sarcomastigota (awaiting allocation) (Family)

Owenella
     Owenella Ulrich & Scofield, 1897 † · Animalia (Kingdom) > Mollusca (Phylum) > Helcionelloida (Class) > Helcionelliformes (Order) > Coreospiridae (Family)
     Owenella Walcott, 1908 † accepted as Marjumia Walcott, 1916 † · Animalia (Kingdom) > Arthropoda (Phylum) > Trilobita (Class) > Ptychopariida (Order) > Marjumiidae (Family)

Owenia
     Owenia delle Chiaje, 1844 · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Oweniida (Order) > Oweniidae (Family)
     Owenia Gray, 1855 † accepted as Owenia Gray, 1855 † (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Owenia F. von Mueller, 1857 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Sapindales (Order) > Meliaceae (Family)
 Owenia Prosch, 1849 accepted as Teuthowenia Chun, 1910 (Invalid: junior homonym of Owenia delle Chiaje, 1844 [Polychaeta]; Teuthowenia is a replacement name) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Teuthoidea (Order) > Cranchiidae (Family)
 Owenia De Vis, 1888 † accepted as Euowenia De Vis, 1891 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Diprotodontia (Order) > Diprotodontidae (Family)
 Owenia J.A. Crux, 1992 † accepted as Isocrystallithus J.W. Verbeek, 1976 † · Chromista (Kingdom) > Haptophyta (Phylum) > Coccolithophyceae (Class) > Coccosphaerales (Order) > Calyptrosphaeraceae (Family)
 Owenia Kölliker, 1853 accepted as Haeckelia Carus in Carus & Gerstaecker, 1863 · Animalia (Kingdom) > Ctenophora (Phylum) > Tentaculata (Class) > Cydippida (Order) > Haeckeliidae (Family)

Oxipterus
 Oxipterus Cuvier, 1817 accepted as Oxipterus Cuvier, 1817 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Artamidae (Family)
 Oxipterus Minà-Palumbo, 1868 accepted as Oxipterus Minà-Palumbo, 1868 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Cetacea (Order) > Odontoceti incertae sedis (Family)

Oxisma
 Oxisma Rafinesque, 1838 accepted as Loreya A.P. de Candolle, 1828 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Myrtales (Order) > Melastomataceae (Family)
     Oxisma Rafinesque, 1818 accepted as Pinna Linnaeus, 1758 · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Pterioida (Order) > Pinnidae (Family)
 Oxisma Rafinesque, 1819 accepted as Pinna Linnaeus, 1758 · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Pterioida (Order) > Pinnidae (Family)

Oxithrombium
     Oxithrombium Feider, 1956 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Actinedida (Order) > Leeuwenhoekiidae (Family)
 Oxithrombium Feider, 1950 accepted as Echinothrombium Womersley, 1937 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Actinedida (Order) > Microtrombidiidae (Family)

Oxiurus
 Oxiurus Sonsino, 1878 accepted as Oxyuris Rudolphi, 1803 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Spirurida (Order) > Oxyuridae (Family)
 Oxiurus Lesson, 1842 accepted as Aphrastura Oberholser, 1899 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Furnariidae (Family)

Oxleya
     Oxleya W.J. Hooker, 1830 accepted as Oxleya W.J. Hooker, 1830 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Sapindales (Order) > Rutaceae (Family)
     Oxleya Domrow, 1965 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Astigmata (Order) > Turbinoptidae (Family)

Oxoplus
 Oxoplus Leconte, 1862 accepted as Crossidius Leconte, 1852 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
 Oxoplus sensu Bates, 1880 accepted as Paroxoplus Chemsak, 1959 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Oxyacanthus
     Oxyacanthus Chevallier, 1836 accepted as Oxyacanthus Chevallier, 1836 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Saxifragales (Order) > Saxifragaceae (Family)
     Oxyacanthus de Lotto, 1971 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Pseudococcidae (Family)
     Oxyacanthus Kamaltynov, 2002 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Amphipoda (Order) > Acanthogammaridae (Family)

Oxyaenodon
     Oxyaenodon Wortman, 1899 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Deltatheroida (Order) > Deltatheroida (awaiting allocation) (Family)
     Oxyaenodon Matthew, 1899 † accepted as Oxyaenodon Wortman, 1899 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Deltatheroida (Order) > Deltatheroida (awaiting allocation) (Family)

Oxybeles
 Oxybeles Richardson, 1846 accepted as Encheliophis Müller, 1842 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Ophidiiformes (Order) > Carapidae (Family)
 Oxybeles Turner, 1940 accepted as Hemibela Turner, 1894 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Oecophoridae (Family)

Oxycephala
     Oxycephala Macquart, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Pyrgotidae (Family)
     Oxycephala Hong, 1979 † accepted as Oxycephala Hong, 1979 † (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Oxycephala Guérin in Duperry, 1838 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Oxycera
 Oxycera Giebel, 1875 accepted as Oxycera Giebel, 1875 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Oxycera Meigen, 1803 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Stratiomyidae (Family)

Oxycharis
     Oxycharis Meyrick, 1939 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Oecophoridae (Family)
     Oxycharis Delucchi, 1954 accepted as Oxycharis Delucchi, 1954 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)

Oxychilus
 Oxychilus Pfeiffer, 1856 accepted as Oxychilus Pfeiffer, 1856 (Unjustified (?) emendation) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Oxychilus Fitzinger, 1833 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Oxychilidae (Family)

Oxychona
     Oxychona Mörch, 1852 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Orthalicidae (Family)
 Oxychona Yankovskii, 1973 accepted as Oxychonina Corliss, 1979 · Chromista (Kingdom) > Ciliophora (Phylum) > Phyllopharyngea (Class) > Chonotrichida (Order) > Stylochonidae (Family)

Oxyclymenia
     Oxyclymenia Hyatt, 1884 † accepted as Oxyclymenia Hyatt, 1884 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Clymeniida (Order) > Clymeniidae (Family)
     Oxyclymenia Wedekind, 1908 † accepted as Oxyclymenia Wedekind, 1908 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Clymeniida (Order) > Platyclymeniidae (Family)
 Oxyclymenia Gümbel, 1863 † accepted as Kosmoclymenia Schindewolf, 1949 † · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Clymeniida (Order) > Kosmoclymeniidae (Family)

Oxycoryphus
     Oxycoryphus Fischer, 1853 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Acrididae (Family)
     Oxycoryphus Cameron, 1904 accepted as Oxycoryphus Cameron, 1904 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)

Oxycrepis
     Oxycrepis Reiche, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
     Oxycrepis Dejean, 1836 accepted as Oxycrepis Reiche, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Oxydactylus
     Oxydactylus Peterson, 1904 † · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Artiodactyla (Order) > Camelidae (Family)
     Oxydactylus Martins, 1965 accepted as Oxydactylus Martins, 1965 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)

Oxydercia
     Oxydercia Felder, 1873 accepted as Oxydercia Felder, 1873 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
 Oxydercia Agassiz, 1846 accepted as Oxidercia Hübner, 1825 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)

Oxyderes
     Oxyderes Jordan, 1928 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Anthribidae (Family)
 Oxyderes Leng & Mutchler, 1914 accepted as Oxyderces Schönherr, 1823 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Oxydiscus
     Oxydiscus de Meijere, 1913 accepted as Oxydiscus de Meijere, 1913 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Limoniidae (Family)
     Oxydiscus Koken, 1889 † accepted as Oxydiscus Koken, 1889 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca incertae sedis (Class) > Gastropoda/Monoplacophora incertae sedis (Order) > Tropidodiscidae (Family)
     Oxydiscus Venturi & Nannarone, 2002 † accepted as Oxydiscus Venturi & Nannarone, 2002 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca incertae sedis (Class) > Gastropoda/Monoplacophora incertae sedis (Order) > Bellerophontidae (Family)
 Oxydiscus Janussen, Tabachnick & Tendal, 2004 accepted as Caulophacus Schulze, 1886 · Animalia (Kingdom) > Porifera (Phylum) > Hexactinellida (Class) > Lyssacinosida (Order) > Rossellidae (Family)

Oxydon
     Oxydon Lessing, 1830 accepted as Oxydon Lessing, 1830 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
 Oxydon accepted as Oxyodon Brauer, 1906 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Epigonidae (Family)

Oxydrepanus
     Oxydrepanus Putzeys, 1867 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Oxydrepanus Bates, 1892 accepted as Trilophus Andrewes, 1927 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Oxydromus
     Oxydromus Grube, 1855 · Animalia (Kingdom) > Annelida (Phylum) > Polychaeta (Class) > Phyllodocida (Order) > Hesionidae (Family)
 Oxydromus Schlegel, 1854 accepted as Oxydromus Schlegel, 1854 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Gruiformes (Order) > Rallidae (Family)

Oxyglossus
     Oxyglossus Tschudi, 1838 accepted as Oxyglossus Tschudi, 1838 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Anura (Order) > Ranidae (Family)
     Oxyglossus Swainson, 1827 accepted as Oxyglossus Swainson, 1827 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
 Oxyglossus Chaudoir, 1843 accepted as Oreodicastes Maindron, 1905 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Oxygnathus
     Oxygnathus Dejean, 1826 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
     Oxygnathus Egerton, 1854 accepted as Oxygnathus Egerton, 1854 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Pisces (awaiting allocation) (Class) > Pisces (awaiting allocation) (Order) > Pisces (awaiting allocation) (Family)

Oxygomphus
     Oxygomphus Tillyard, 1917 accepted as Oxygomphus Tillyard, 1917 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Odonata (Order) > Odonata (awaiting allocation) (Family)
     Oxygomphus Lacroix, 1921 accepted as Oxygomphus Lacroix, 1921 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Odonata (Order) > Odonata (awaiting allocation) (Family)

Oxygona
     Oxygona Dejean, 1835 accepted as Oxygona Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
     Oxygona Erichson in Schomburgk, 1848 accepted as Oxygona Erichson in Schomburgk, 1848 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
 Oxygona Chevrolat, 1837 accepted as Platiprosopus Chevrolat, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Oxygonia
     Oxygonia Fairmaire, 1846 accepted as Oxygonia Fairmaire, 1846 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Membracidae (Family)
     Oxygonia Melichar, 1926 accepted as Oxygonia Melichar, 1926 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Jassidae (Family)
     Oxygonia Mannerheim, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Oxygonium
     Oxygonium Basilewsky, 1951 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Oxygonium K.B. Presl, 1836 accepted as Diplazium O. Swartz, 1801 · Plantae (Kingdom) > Tracheophyta (Phylum) > Polypodiopsida (Class) > Polypodiales (Order) > Athyriaceae (Family)

Oxygonus
     Oxygonus Leconte, 1863 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Elateridae (Family)
 Oxygonus Gistl, 1848 accepted as Canis Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Canidae (Family)
 Oxygonus Clark, 1864 accepted as Platiprosopus Chevrolat, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Oxygyne
     Oxygyne Forel, 1901 accepted as Oxygyne Forel, 1901 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
     Oxygyne Schlechter, 1906 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Dioscoreales (Order) > Burmanniaceae (Family)

Oxylepis
     Oxylepis Bentham, 1841 accepted as Oxylepis Bentham, 1841 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
 Oxylepis Desbrochers, 1891 accepted as Oxylepus Desbrochers, 1885 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Oxylobus
     Oxylobus Stål, 1870 accepted as Oxylobus Stål, 1870 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Oxylobus Chaudoir, 1855 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
     Oxylobus (A.P. de Candolle) A. Gray, 1880 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)

Oxyloma
     Oxyloma Gardner & Campbell, 2002 † accepted as Oxyloma Gardner & Campbell, 2002 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Veneroida (awaiting allocation) (Family)
     Oxyloma Westerlund, 1885 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Succineidae (Family)

Oxymeris
     Oxymeris Dall, 1903 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Neogastropoda (Order) > Terebridae (Family)
 Oxymeris A.P. de Candolle, 1828 accepted as Leandra Raddi, 1820 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Myrtales (Order) > Melastomataceae (Family)

Oxymitra
     Oxymitra Bischoff ex Lindenberg, 1829 · Plantae (Kingdom) > Marchantiophyta (Phylum) > Marchantiopsida (Class) > Marchantiales (Order) > Oxymitraceae (Family)
 Oxymitra (Blume) J.D. Hooker & T. Thomson, 1855 accepted as Friesodielsia C.G.G.J. van Steenis, 1948 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Magnoliales (Order) > Annonaceae (Family)

Oxynema
     Oxynema Linstow, 1899 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Spirurida (Order) > Subuluridae (Family)
     Oxynema Chatchawan, Komárek, Strunecky, Smarda & Peerapornpisal, 2012 · Bacteria (Kingdom) > Cyanobacteria (Phylum) > Cyanophyceae (Class) > Oscillatoriales (Order) > Microcoleaceae (Family)

Oxynotus
     Oxynotus Rafinesque, 1810 · Animalia (Kingdom) > Chordata (Phylum) > Chondrichthyes (Class) > Squaliformes (Order) > Oxynotidae (Family)
     Oxynotus Swainson in Richardson, 1832 accepted as Oxynotus Swainson in Richardson, 1832 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Campephagidae (Family)
     Oxynotus Laporte, 1832 accepted as Oxynotus Laporte, 1832 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
 Oxynotus Hancock, 1900 accepted as Oxytettix Rehn, 1929 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tetrigidae (Family)

Oxyoides
     Oxyoides Zheng & Fu, 1994 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Acrididae (Family)
     Oxyoides Zhen & Fu, 1994 accepted as Oxyoides Zhen & Fu, 1994 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Orthoptera (awaiting allocation) (Family)

Oxyomus
 Oxyomus Blanchard, 1843 accepted as Ataenius Harold, 1867 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Oxyomus Erichson, 1844 accepted as Oxyomus Dejean, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Oxyomus Kirby & Spence, 1828 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
     Oxyomus Dejean, 1833 accepted as Oxyomus Dejean, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Oxyomus Stephens, 1839 accepted as Oxyomus Dejean, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Oxyomus Eschscholtz, 1833 accepted as Oxyomus Dejean, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Oxyomus Laporte, 1840 accepted as Oxyomus Dejean, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)
 Oxyomus Mannerheim, 1843 accepted as Aegialia Latreille, 1807 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Oxyophthalmus
     Oxyophthalmus Hochhuth, 1847 accepted as Oxyophthalmus Hochhuth, 1847 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
 Oxyophthalmus Saussure, 1862 accepted as Oxyophthalma Saussure, 1869 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Mantodea (Order) > Tarachodidae (Family)

Oxyopisthen
 Oxyopisthen Thomson, 1858 accepted as Belorhynus Guérin-Ménéville, 1844 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Dryophthoridae (Family)
 Oxyopisthen Lacordaire, 1866 accepted as Korotyaevius Alonso-Zarazaga & Lyal, 1999 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Dryophthoridae (Family)

Oxyops
     Oxyops Schönherr, 1826 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Oxyops Saussure, 1869 accepted as Oxyopsis Caudell, 1904 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Mantodea (Order) > Mantidae (Family)
     Oxyops Schönherr, 1823 accepted as Oxyops Schönherr, 1826 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)

Oxyopsis
     Oxyopsis Caudell, 1904 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Mantodea (Order) > Mantidae (Family)
 Oxyopsis accepted as Oxopsis Nordenskiöld, 1905 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Actinedida (Order) > Hydrodromidae (Family)

Oxyperas
     Oxyperas Mörch, 1853 · Animalia (Kingdom) > Mollusca (Phylum) > Bivalvia (Class) > Venerida (Order) > Mactridae (Family)
 Oxyperas Thomson, 1880 accepted as Protaetia Burmeister, 1842 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Oxyphyllum
     Oxyphyllum R. Philippi, 1860 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
     Oxyphyllum Hancock, 1909 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tetrigidae (Family)

Oxypleura
     Oxypleura Amyot & Serville, 1843 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Cicadidae (Family)
 Oxypleura Pomel, 1887 accepted as Clypeaster Lamarck, 1801 (junior homonym, non Oxypleura Mulsant, 1840 (Coleoptera), nec Oxypleura Amyot & Audinet-Serville, 1849 (Hemiptera)) · Animalia (Kingdom) > Echinodermata (Phylum) > Echinoidea (Class) > Clypeasteroida (Order) > Clypeasteridae (Family)

Oxypogon
     Oxypogon Gould, 1848 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Apodiformes (Order) > Trochilidae (Family)
     Oxypogon Rafinesque, 1819 accepted as Oxypogon Rafinesque, 1819 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)

Oxypora
 Oxypora Warren, 1912 accepted as Oxychora Warren, 1898 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Geometridae (Family)
     Oxypora Saville-Kent, 1871 · Animalia (Kingdom) > Cnidaria (Phylum) > Anthozoa (Class) > Scleractinia (Order) > Lobophylliidae (Family)

Oxyporus
     Oxyporus (Bourdot & Galzin) Donk, 1933 · Fungi (Kingdom) > Basidiomycota (Phylum) > Agaricomycetes (Class) > Agaricomycetes incertae sedis (Order) > Agaricomycetes incertae sedis (Family)
     Oxyporus Fabricius, 1775 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
 Oxyporus Brookes, 1828 accepted as Casuarius Brisson, 1760 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Casuariiformes (Order) > Casuariidae (Family)

Oxypristis
     Oxypristis Signoret, 1861 accepted as Oxypristis Signoret, 1861 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
 Oxypristis Hoffmann, 1912 accepted as Anoxypristis White & Moy-Thomas, 1941 · Animalia (Kingdom) > Chordata (Phylum) > Chondrichthyes (Class) > Pristiformes (Order) > Pristidae (Family)

Oxyprora
     Oxyprora accepted as Oxyprora (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Noctuidae (Family)
     Oxyprora Stål, 1873 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tettigoniidae (Family)
     Oxyprora Hoare, Mapes & Yancey, 2002 † accepted as Oxyprora Hoare, Mapes & Yancey, 2002 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Rostroconchia (Class) > Conocardioida (Order) > Conocardiidae (Family)
 Oxyprora Brunner von Wattenwyl, 1878 accepted as Oxyprorella Giglio-Tos, 1898 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tettigoniidae (Family)

Oxypterus
     Oxypterus Gistl, 1834 accepted as Oxypterus Gistl, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Oxypterus Rafinesque, 1814 accepted as Oxypterus Rafinesque, 1814 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Cetacea (Order) > Odontoceti incertae sedis (Family)
     Oxypterus Fleming, 1822 accepted as Oxypterus Fleming, 1822 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
 Oxypterus Faust, 1896 accepted as Oxytenopterus Berg, 1898 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Curculionidae (Family)
 Oxypterus Schoch, 1894 accepted as Oxyperatex Krikken, 1982 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Scarabaeidae (Family)

Oxypteryx
     Oxypteryx Rebel, 1911 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Lepidoptera (Order) > Gelechiidae (Family)
 Oxypteryx E.L. Greene, 1897 accepted as Asclepias Linnaeus, 1753 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Gentianales (Order) > Apocynaceae (Family)

Oxyrhachis
     Oxyrhachis Germar, 1833 accepted as Oxyrhachis Germar, 1833 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Membracidae (Family)
     Oxyrhachis Pilger, 1932 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Poales (Order) > Poaceae (Family)

Oxyrhina
     Oxyrhina Soares, 1944 accepted as Oxyrhina Soares, 1944 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Opiliones (Order) > Gonyleptidae (Family)
     Oxyrhina Jan, 1862 accepted as Oxyrhina Jan, 1862 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Squamata (Order) > Colubridae (Family)
 Oxyrhina Meigen, 1838 accepted as Trigonometopus Macquart, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Lauxaniidae (Family)
 Oxyrhina Agassiz, 1838 accepted as Isurus Rafinesque, 1810 · Animalia (Kingdom) > Chordata (Phylum) > Chondrichthyes (Class) > Lamniformes (Order) > Lamnidae (Family)
 Oxyrhina Zetterstedt, 1842 accepted as Acrometopia Schiner, 1862 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Chamaemyiidae (Family)

Oxyrhinus
     Oxyrhinus Pelzeln, 1883 accepted as Oxyrhinus Pelzeln, 1883 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
     Oxyrhinus Amyot & Serville, 1843 accepted as Oxyrhinus Amyot & Serville, 1843 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)

Oxyrhynchus
     Oxyrhynchus Spix, 1824 accepted as Oxyrhynchus Spix, 1824 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Amphibia (awaiting allocation) (Order) > Amphibia (awaiting allocation) (Family)
     Oxyrhynchus Quenstedt, 1868 accepted as Oxyrhynchus Quenstedt, 1868 · Animalia (Kingdom) > Brachiopoda (Phylum) > Brachiopoda (awaiting allocation) (Class) > Brachiopoda (awaiting allocation) (Order) > Brachiopoda (awaiting allocation) (Family)
     Oxyrhynchus Herrmannsen, 1847 accepted as Oxyrhynchus Herrmannsen, 1847 (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Oxyrhynchus T.S. Brandegee, 1912 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)
 Oxyrhynchus Agassiz, 1845 accepted as Ozirhincus Rondani, 1840 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Cecidomyiidae (Family)
 Oxyrhynchus de Buen, 1926 accepted as Raja Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Chondrichthyes (Class) > Rajiformes (Order) > Rajidae (Family)
 Oxyrhynchus Temminck in Temminck & Laugier, 1822 accepted as Oxyruncus Temminck, 1820 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Tyrannidae (Family)
 Oxyrhynchus Leach in Tuckey, 1818 accepted as Mormyrops Müller, 1843 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Osteoglossiformes (Order) > Mormyridae (Family)
 Oxyrhynchus Schönherr, 1823 accepted as Cryptoderma Ritsema, 1885 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Dryophthoridae (Family)

Oxyrhyncus
 Oxyrhyncus Swainson, 1821 accepted as Oxyruncus Temminck, 1820 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Tyrannidae (Family)
 Oxyrhyncus Rondani, 1856 accepted as Ozirhincus Rondani, 1840 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Cecidomyiidae (Family)
 Oxyrhyncus Dumeril, 1827 accepted as Cryptoderma Ritsema, 1885 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Dryophthoridae (Family)

Oxyria
     Oxyria J. Hill, 1765 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Caryophyllales (Order) > Polygonaceae (Family)
     Oxyria Yu, 2005 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Ceratopogonidae (Family)

Oxyrrhynchus
 Oxyrrhynchus Gemminger & Harold, 1871 accepted as Cryptoderma Ritsema, 1885 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Dryophthoridae (Family)
 Oxyrrhynchus Walker, 1856 accepted as Ozirhincus Rondani, 1840 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Cecidomyiidae (Family)
 Oxyrrhynchus Thon in Ersch & Gruber, 1836 accepted as Oxyruncus Temminck, 1820 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Tyrannidae (Family)

Oxyrynchus
 Oxyrynchus Loew, 1850 accepted as Oxyrynchus Loew, 1850 (Misspelling) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Diptera (awaiting allocation) (Family)
 Oxyrynchus Wied-Neuwied, 1827 accepted as Oxyrynchus Wied-Neuwied, 1827 (Misspelling) · Animalia (Kingdom) > Chordata (Phylum) > Amphibia (Class) > Amphibia (awaiting allocation) (Order) > Amphibia (awaiting allocation) (Family)
 Oxyrynchus Swainson, 1836 accepted as Oxyruncus Temminck, 1820 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Tyrannidae (Family)

Oxysoma
     Oxysoma Nicolet in Gay, 1849 · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Anyphaenidae (Family)
     Oxysoma Pelegrin Franganillo y Balbao, 1926 † · Animalia (Kingdom) > Arthropoda (Phylum) > Arachnida (Class) > Araneae (Order) > Thomisidae (Family)
 Oxysoma Schneider, 1866 accepted as Oxysomatium Railliet & Henry, 1913 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Spirurida (Order) > Cosmocercidae (Family)
 Oxysoma Kraatz, 1857 accepted as Piochardia Heyden, 1870 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)

Oxysternus
     Oxysternus Dejean, 1833 accepted as Oxysternus Dejean, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Histeridae (Family)
 Oxysternus Latreille, 1834 accepted as Hemiops Laporte, 1836 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Histeridae (Family)
 Oxysternus Erichson, 1834 accepted as Oxysternus Dejean, 1833 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Histeridae (Family)

Oxystethus
     Oxystethus Redtenbacher, 1891 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tettigoniidae (Family)
     Oxystethus Fairmaire, 1883 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Elateridae (Family)

Oxystigma
     Oxystigma Harms in Engler & Prantl, 1897 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)
     Oxystigma Selys, 1862 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Odonata (Order) > Megapodagrionidae (Family)

Oxystoma
     Oxystoma Duméril, 1806 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Brentidae (Family)
 Oxystoma Stephens, 1829 accepted as Exapion Bedel, 1887 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Brentidae (Family)
 Oxystoma Eschweiler, 1824 accepted as Graphis Adanson, 1763 · Fungi (Kingdom) > Ascomycota (Phylum) > Lecanoromycetes (Class) > Ostropales (Order) > Graphidaceae (Family)
 Oxystoma Bütschli, 1874 accepted as Oxystomina Filipjev, 1921 (homonym for Oxystoma Dumeril, 1806) · Animalia (Kingdom) > Nematoda (Phylum) > Enoplea (Class) > Ironida (Order) > Oxystominidae (Family)

Oxystomina
     Oxystomina Filipjev, 1921 · Animalia (Kingdom) > Nematoda (Phylum) > Enoplea (Class) > Ironida (Order) > Oxystominidae (Family)
 Oxystomina Baylis & Daubney, 1926 accepted as Oxystomina Filipjev, 1921 · Animalia (Kingdom) > Nematoda (Phylum) > Enoplea (Class) > Ironida (Order) > Oxystominidae (Family)

Oxystomus
     Oxystomus Swainson, 1837 accepted as Oxystomus Swainson, 1837 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Aves (awaiting allocation) (Order) > Aves (awaiting allocation) (Family)
     Oxystomus Rafinesque, 1810 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Anguilliformes (Order) > Ophichthidae (Family)
 Oxystomus Fischer de Waldheim, 1803 accepted as Trichechus Linnaeus, 1758 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Sirenia (Order) > Trichechidae (Family)
 Oxystomus Dejean, 1825 accepted as Forcipator Maindron, 1904 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)

Oxytaenia
     Oxytaenia Sack in Lindner, 1939 accepted as Oxytaenia Sack in Lindner, 1939 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Diptera (Order) > Sciomyzidae (Family)
     Oxytaenia Förster, 1868 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Ichneumonidae (Family)

Oxytelosus
 Oxytelosus Cameron, 1950 accepted as Anotylus Thomson, 1859 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
 Oxytelosus Fagel, 1956 accepted as Anotylus Thomson, 1859 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)
 Oxytelosus Bernhauer, 1940 accepted as Anotylus Thomson, 1859 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Staphylinidae (Family)

Oxytes
     Oxytes Giebel, 1848 accepted as Oxytes Giebel, 1848 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Pisces (awaiting allocation) (Class) > Pisces (awaiting allocation) (Order) > Pisces (awaiting allocation) (Family)
 Oxytes Pfeiffer, 1855 † accepted as Oxytesta Zilch, 1956 · Animalia (Kingdom) > Mollusca (Phylum) > Gastropoda (Class) > Stylommatophora (Order) > Ariophantidae (Family)

Oxytettix
     Oxytettix Rehn, 1929 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Orthoptera (Order) > Tetrigidae (Family)
     Oxytettix Ribaut, 1942 accepted as Oxytettix Ribaut, 1942 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Cicadellidae (Family)

Oxyteuthis
     Oxyteuthis Stolley, 1911 † · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Belemnitida (Order) > Belemnitida (awaiting allocation) (Family)
     Oxyteuthis Lissajous, 1915 † accepted as Oxyteuthis Lissajous, 1915 † (unassessed) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)

Oxythyreus
     Oxythyreus Westwood, 1842 accepted as Oxythyreus Westwood, 1842 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Hemiptera (awaiting allocation) (Family)
     Oxythyreus Bronn & Roemer, 1852 † · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Homolodromioidea (awaiting allocation) (Family)
 Oxythyreus Reuss, 1858 † accepted as Konidromites Schweitzer & Feldmann, 2010 † · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Konidromitidae (Family)

Oxytricha
     Oxytricha Bory de Saint-Vincent in Lamouroux et al., 1824 · Chromista (Kingdom) > Ciliophora (Phylum) > Spirotrichea (Class) > Hypotrichida (Order) > Oxytrichidae (Family)
     Oxytricha Ehrenberg, 1830 accepted as Oxytricha Ehrenberg, 1830 (unassessed) · Protozoa (Kingdom) > (Phylum) > Protozoa (awaiting allocation) (Class) > (Order) > (Family)

Oxytropis
     Oxytropis Fitzinger, 1843 accepted as Oxytropis Fitzinger, 1843 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Reptilia (Class) > Reptilia (awaiting allocation) (Order) > Reptilia (awaiting allocation) (Family)
     Oxytropis A.P. de Candolle, 1802 · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Fabales (Order) > Fabaceae (Family)

Oxyura
     Oxyura Bonaparte, 1831 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Anseriformes (Order) > Anatidae (Family)
     Oxyura A.P. de Candolle, 1836 accepted as Oxyura A.P. de Candolle, 1836 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Asterales (Order) > Asteraceae (Family)
 Oxyura Agassiz, 1846 accepted as Oxura Kirby, 1819 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Tenebrionidae (Family)

Oxyurichthys
     Oxyurichthys Bleeker, 1857 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Gobiidae (Family)
     Oxyurichthys Bleeker, 1857 · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Gobiidae (Family)

Oxyurus
     Oxyurus Lamarck, 1817 accepted as Oxyurus Lamarck, 1817 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hymenoptera (Order) > Hymenoptera (awaiting allocation) (Family)
     Oxyurus Koch, 1847 accepted as Oxyurus Koch, 1847 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Diplopoda (Class) > Polydesmida (Order) > Xystodesmidae (Family)
     Oxyurus Rafinesque, 1810 accepted as Oxyurus Rafinesque, 1810 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Anguilliformes (Order) > Congridae (Family)
 Oxyurus Swainson, 1827 accepted as Aphrastura Oberholser, 1899 · Animalia (Kingdom) > Chordata (Phylum) > Aves (Class) > Passeriformes (Order) > Furnariidae (Family)
 Oxyurus Lamarck, 1816 accepted as Oxyuris Rudolphi, 1803 · Animalia (Kingdom) > Nematoda (Phylum) > Chromadorea (Class) > Spirurida (Order) > Oxyuridae (Family)

Ozaena
 Ozaena Rafinesque, 1814 accepted as Eledone Leach, 1817 · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Octopoda (Order) > Octopodidae (Family)
     Ozaena Olivier, 1812 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Ozaena Menke, 1830 accepted as Ozaena Menke, 1830 (Misspelling) · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Octopoda (Order) > Octopodidae (Family)

Oziotelphusa
     Oziotelphusa Müller, 1887 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Gecarcinucidae (Family)
 Oziotelphusa Alcock, 1909 accepted as Spiralothelphusa Bott, 1968 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Gecarcinucidae (Family)

Ozius
     Ozius Desmarest, 1825 accepted as Ozius Desmarest, 1825 · Animalia (Kingdom) > Arthropoda (Phylum) > Crustacea (awaiting allocation) (Class) > Crustacea (awaiting allocation) (Order) > Crustacea (awaiting allocation) (Family)
     Ozius H. Milne Edwards, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Malacostraca (Class) > Decapoda (Order) > Oziidae (Family)

Ozodeocerus
 Ozodeocerus Agassiz, 1846 accepted as Ozodecerus Chevrolat, 1839 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Brentidae (Family)
 Ozodeocerus Gemminger & Harold, 1872 accepted as Ozodecerus Chevrolat, 1839 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Brentidae (Family)

Ozodes
     Ozodes Audinet-Serville, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)
     Ozodes Lacordaire, 1830 accepted as Ozodes Audinet-Serville, 1834 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Cerambycidae (Family)

Ozoena
 Ozoena Brullé in Audouin & Brullé, 1834 accepted as Ozaena Olivier, 1812 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Carabidae (Family)
 Ozoena Rafinesque, 1814 accepted as Eledone Leach, 1817 · Animalia (Kingdom) > Mollusca (Phylum) > Cephalopoda (Class) > Octopoda (Order) > Octopodidae (Family)

Ozolictis
     Ozolictis Gloger, 1842 accepted as Ozolictis Gloger, 1842 (unassessed) · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Mammalia (awaiting allocation) (Order) > Mammalia (awaiting allocation) (Family)
 Ozolictis Gloger, 1841 accepted as Ictonyx Kaup, 1835 · Animalia (Kingdom) > Chordata (Phylum) > Mammalia (Class) > Carnivora (Order) > Mustelidae (Family)

Ozomena
     Ozomena Dejean, 1835 accepted as Ozomena Dejean, 1835 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
     Ozomena Harold, 1876 accepted as Ozomena Harold, 1876 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Coleoptera (awaiting allocation) (Family)
 Ozomena Chevrolat, 1849 accepted as Cerophysa Chevrolat, 1837 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)
 Ozomena Chevrolat, 1837 accepted as Theopea Baly, 1864 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Coleoptera (Order) > Chrysomelidae (Family)

Ozophora
     Ozophora J.Agardh, 1892 · Plantae (Kingdom) > Rhodophyta (Phylum) > Florideophyceae (Class) > Gigartinales (Order) > Phyllophoraceae (Family)
     Ozophora Uhler, 1871 · Animalia (Kingdom) > Arthropoda (Phylum) > Insecta (Class) > Hemiptera (Order) > Lygaeidae (Family)

Ozorhacus
     Ozorhacus Attems, 1932 accepted as Ozorhacus Attems, 1932 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Myriapoda (awaiting allocation) (Class) > Myriapoda (awaiting allocation) (Order) > Myriapoda (awaiting allocation) (Family)
     Ozorhacus Attems, 1938 accepted as Ozorhacus Attems, 1938 (unassessed) · Animalia (Kingdom) > Arthropoda (Phylum) > Myriapoda (awaiting allocation) (Class) > Myriapoda (awaiting allocation) (Order) > Myriapoda (awaiting allocation) (Family)

Ozotis
 Ozotis Paetel, 1875 accepted as Ozotis Paetel, 1875 (Misspelling) · Animalia (Kingdom) > Mollusca (Phylum) > Mollusca (awaiting allocation) (Class) > Mollusca (awaiting allocation) (Order) > Mollusca (awaiting allocation) (Family)
     Ozotis Rafinesque, 1838 accepted as Ozotis Rafinesque, 1838 (unassessed) · Plantae (Kingdom) > Tracheophyta (Phylum) > Magnoliopsida (Class) > Sapindales (Order) > Sapindaceae (Family)
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