Abedinium A.R. Loeblich Jr. & A.R. Loeblich III, 1966 (habitat flag source)
Abroteia J.G. Agardh, 1876 (habitat flag source)
Acanthocerataceae Round, Crawford & Mann, 1990 accepted as Chaetocerotaceae Ralfs, 1861 (habitat flag source)
Acanthococcus J.D. Hooker & W.H. Harvey, 1845 (habitat flag source)
Acanthopeltis Okamura in Yatabe, 1892 (habitat flag source)
Achnantheiopsis Lange-Bertalot, 1997 (habitat flag source)
Acroblaste Reinsch, 1879 (habitat flag source)
Acrocarpus Kützing, 1843 accepted as Gelidiella Feldmann & G. Hamel, 1934 (habitat flag source)
Acrochaetiaceae Fritsch ex W.R. Taylor, 1957 (habitat flag source)
Acrodiscus Zanardini, 1869 (habitat flag source)
Acropeltis Montagne, 1837 accepted as Gelidium J.V.F. Lamouroux, 1813 (habitat flag source)
Acrosymphytaceae S.C. Lindstrom, 1987 (habitat flag source)
Acrosymphyton brainardii P.S. Vroom & I.A. Abbott, 2004 (habitat flag source)
Acrosymphyton caribaeum (J.G. Agardh) Sjöstedt, 1926 (habitat flag source)
Acrosymphyton firmum M.W. Hawkes, 1982 (habitat flag source)
Acrosymphyton purpuriferum (J.G. Agardh) Sjöstedt, 1926 (habitat flag source)
Acrothamnion J.G. Agardh, 1892 (habitat flag source)
Acrothamnion preissii (Sonder) E.M. Wollaston, 1968 (habitat flag source)
Acrothamnion pulchellum J.G. Agardh, 1892 accepted as Acrothamnion preissii (Sonder) E.M. Wollaston, 1968 (habitat flag source)
Acrotylaceae Schmitz, 1892 (habitat flag source)
Acrotylus J.G. Agardh, 1849 (habitat flag source)
Actinellipsoidion H. Ettl, 1977 (habitat flag source)
Actinodictyon Pantocsek, 1889 † (habitat flag source)
Actinotrichia Decaisne, 1842 (habitat flag source)
Adelophycus Kraft, 1994 (habitat flag source)
Adlafia G. Moser, H. Lange-Bertalot & D. Metzeltin, 1998 (habitat flag source)
Aeodes J.G. Agardh, 1876 (habitat flag source)
Agardhinula De Toni, 1897 (habitat flag source)
Ahnfeltia Fries, 1836 (habitat flag source)
Ahnfeltiaceae C.A. Maggs & C.M. Pueschel (habitat flag source)
Akalaphycus J.M. Huisman, I.A. Abbott & A.R. Sherwood, 2004 (habitat flag source)
Akalaphycus liagoroides (Yamada) Huisman, I.A. Abbott & A.R. Sherwood, 2004 (habitat flag source)
Aldavemyxa Skvortzov, 1972 (habitat flag source)
Alloioneis K.M. Schumann ex P.T. Cleve, 1878 accepted as Scoliopleura Grunow, 1860 (habitat flag source)
Alveus I. Kaczmarska & G.A. Fryxell, 1996 (habitat flag source)
Amphicampa (Ehrenberg) Ralfs, 1861 (habitat flag source)
Amphiceratium Vanhöffen, 1896 accepted as Tripos Bory de Saint-Vincent, 1823 (habitat flag source)
Amphicocconeis M. De Stefano & D. Marino, 2003 (habitat flag source)
Amphidinium Claparède & Lachmann, 1859 (habitat flag source)
Amphiplexia J.G. Agardh, 1892 (habitat flag source)
Amyloodinium E. Brown & Hovasse, 1946 (habitat flag source)
Amylophora J.G. Agardh, 1892 accepted as Nizymenia Sonder, 1855 (habitat flag source)
Anacanthoica lithostratos (Schiller) Norris, 1984 (habitat flag source)
Anatheca F. Schmitz, 1897 (habitat flag source)
Ankylonoton luteum Veer, 1970 accepted as Ankylochrysis lutea (Veer) Billard, 1995 (habitat flag source)
Antrocentrum Kraft & Min-Thein, 1983 (habitat flag source)
Apodococcus F. Hindák, 1984 (habitat flag source)
Apona Adanson, 1763 accepted as Lemanea Bory de Saint-Vincent, 1808 (habitat flag source)
Apophlaea Harvey, 1845 (habitat flag source)
Archaeosphaerodiniopsis Rampi, 1943 (habitat flag source)
Areschougiaceae J.G. Agardh, 1876 (habitat flag source)
Asparagopsis Montagne, 1840 (habitat flag source)
Asterodinium Sournia, 1972 (habitat flag source)
Asteromenia J.M. Huisman & A.J.K. Millar, 1996 (habitat flag source)
Aureodinium Dodge, 1967 (habitat flag source)
Aurosphaera J. Schiller, 1916 (habitat flag source)
Austroclonium Min-Thein & Womersley, 1976 (habitat flag source)
Austroclonium charoides (Harvey) Min-Thein & Womersley, 1976 (habitat flag source)
Austrophyllis H.B.S. Womersley & R.E. Norris, 1971 (habitat flag source)
Auxenochlorella (I. Shihira & R.W. Krauss) T. Kalina & M. Puncochárová, 1987 (habitat flag source)
Baileya Kützing, 1857 accepted as Tuomeya Harvey, 1858 (habitat flag source)
Balbiania Sirodot, 1876 (habitat flag source)
Balbiania boweri (Murray & Barton) De Toni, 1924 accepted as Audouinella boweri (Murray & E.S. Barton) Hamel, 1925 (habitat flag source)
Balbiania investiens (Lenormand ex Kützing) Sirodot, 1876 (habitat flag source)
Balbiania meiospora Skuja, 1944 (habitat flag source)
Balbianiaceae R.G. Sheath & K.M. Müller, 1999 (habitat flag source)
Ballia callitricha (C. Agardh) Kützing, 1843 (habitat flag source)
Balliaceae H.-G. Choi, G.T. Kraft & G.W. Saunders, 2000 (habitat flag source)
Bangia Lyngbye, 1819 (habitat flag source)
Bangiella Gaillon, 1833 accepted as Bangiadulcis W.A. Nelson, 2007 accepted as Bangia Lyngbye, 1819 (habitat flag source)
Bangiella atropurpurea (Roth) Gaillon, 1833 (habitat flag source)
Bangiopsis F. Schmitz, 1896 (habitat flag source)
Baylesia Setchell, 1912 accepted as Schimmelmannia Schousboe ex Kützing, 1849 (habitat flag source)
Beckerella Kylin, 1956 accepted as Ptilophora Kützing, 1847 (habitat flag source)
Beckingia Ruinen, 1938 (habitat flag source)
Beckingia salina Ruinen, 1938 (habitat flag source)
Berghiella Kofoid & Michener, 1911 (habitat flag source)
Beringia Perestenko, 1975 (habitat flag source)
Bertholdia F. Schmitz, 1889 accepted as Schmitzia P.C. Silva, 1959 (habitat flag source)
Besa Setchell, 1912 (habitat flag source)
Biceratium Vanhöffen, 1896 accepted as Tripos Bory de Saint-Vincent, 1823 (habitat flag source)
Bifida Stackhouse, 1809 accepted as Rhodophyllis Kützing, 1847 (habitat flag source)
Bifida divaricata Stackhouse, 1809 accepted as Rhodophyllis divaricata (Stackhouse) Papenfuss, 1950 (habitat flag source)
Bindera Harvey, 1859 accepted as Webervanbossea G. De Toni, 1936 (habitat flag source)
Binderella F. Schmitz, 1896 accepted as Amphiplexia J.G. Agardh, 1892 (habitat flag source)
Binderella neglecta F. Schmitz, 1897 accepted as Amphiplexia hymenocladioides J.G. Agardh, 1892 (habitat flag source)
Blastophye J.G. Agardh, 1892 accepted as Cryptonemia J.G. Agardh, 1842 (habitat flag source)
Boldia W.R. Herndon, 1964 (habitat flag source)
Boldia angustata Deason & Nichols, 1970 (habitat flag source)
Bonnemaisonia C.A. Agardh, 1822 (habitat flag source)
Borrichius S.F. Gray, 1821 accepted as Dudresnaya P.L. Crouan & H.M. Crouan, 1835 (habitat flag source)
Bostrychiocolax G.C. Zuccarello & J.A. West, 1994 (habitat flag source)
Bothrochloris Pascher, 1932 (habitat flag source)
Bothrochloris longeciliata Pascher, 1932 (habitat flag source)
Botryocladia (J.G. Agardh) Kylin, 1931 (habitat flag source)
Bowiesia Greville, 1830 accepted as Delisea J.V.F. Lamouroux in F. Cuvier, 1819 (habitat flag source)
Brachycladia Sonder, 1855 accepted as Dichotomaria Lamarck, 1816 (habitat flag source)
Brightwellia Ralfs in Pritchard, 1861 † (habitat flag source)
Bryopsidales (awaiting allocation) (habitat flag source)
Calkinsiella Skvortzov, 1969 (habitat flag source)