Abyssorhynchia Zezina, 1980 (name verified source)
Abyssorhynchia Zezina, 1980 (basis of record)
Acanthaphritis Günther, 1880 (verified source for family)
Acanthohamingia Ikeda, 1910 (name verified source)
Acanthohamingia Ikeda, 1910 (basis of record)
Acanthopsaron Fricke, 2024 (verified source for family)
Acanthotheca Vendrasco, Kouchinsky, Porter & Fernandez, 2011 † (verified source for family)
Acropomatidae Gill, 1893 (taxonomy source)
Acropomatiformes (basis of record)
Actinoposthiidae Hooge, 2001 (basis of record)
Acutocoxae Rauschert, 2017 (additional source)
Adeorbella Briart & Cornet, 1887 † (current name source)
Adeorbella Briart & Cornet, 1887 † (verified source for family)
Aestuariumcypraea Daughenbaugh & Bridges, 2022 † accepted as Siphocypraea Heilprin, 1886 † (source of synonymy)
Aestuariumcypraea Daughenbaugh & Bridges, 2022 † accepted as Siphocypraea Heilprin, 1886 † (basis of record)
Agilestia Friend, 1982 (verified source for family)
Agnesia Michaelsen, 1898 accepted as Agnezia C. Monniot & F. Monniot, 1991 (source of synonymy)
Ainigma Helfer, 1938 accepted as Ascorhynchus Sars, 1878 (verified source for family)
Aktschagylia Starobogatov, 1970 (verified source for family)
Aktschagylia Starobogatov, 1970 (current name source)
Albidiator Lowry & Myers, 2019 (verified source for family)
Alexlutheria Karling, 1956 (verified source for family)
Alienella Starobogatov & Zatravkin, 1985 accepted as Sibirovalvata Starobogatov & Streletzkaja, 1967 (source of synonymy)
Alienella Starobogatov & Zatravkin, 1985 accepted as Sibirovalvata Starobogatov & Streletzkaja, 1967 (basis of record)
Alluroteuthidae accepted as Neoteuthidae Naef, 1921 (source of synonymy)
Altadema Kues, 2002 † (verified source for family)
Amekicarcinus Schweitzer, Odumodu & Feldmann, 2016 † (verified source for family)
Amniciana Servain, 1888 accepted as Pisidium C. Pfeiffer, 1821 (source of synonymy)
Amnigenia Hall, 1885 † (current name source)
Amnigenia Hall, 1885 † (verified source for family)
Amnigeniidae Khalfin, 1948 † (taxonomy source)
Amnigeniidae Khalfin, 1948 † (current name source)
Ampezzania Allasinaz in Allasinaz & Zardini, 1977 † (current name source)
Ampezzania Allasinaz in Allasinaz & Zardini, 1977 † (basis of record)
Ampezzania Allasinaz in Allasinaz & Zardini, 1977 † (verified source for family)
Amphiphora Alloiteau & Bernier, 1969 † accepted as Cyathophora Michelin, 1843 † (source of synonymy)
Amphisopidae Nicholls, 1943 (habitat flag source)
Amplidrupa Vermeij, 2023 (basis of record)
Amplidrupa Vermeij, 2023 (current name source)
Amplidrupa Vermeij, 2023 (verified source for family)
Amurohenslowiana Korniushin, 1996 accepted as Henslowiana Servain, 1888 (basis of record)
Amurohenslowiana Korniushin, 1996 accepted as Henslowiana Servain, 1888 (source of synonymy)
Anaucella Pchelintseva, 1955 † accepted as Buchia Rouillier, 1845 † (basis of record)
Anaucella Pchelintseva, 1955 † accepted as Buchia Rouillier, 1845 † (source of synonymy)
Ancistrocheiridae Pfeffer, 1912 (taxonomy source)
Angulocarinella Korchagin, 2001 † accepted as Whiteinella Pessagno, 1967 † (source of synonymy)
Angulomphalus Gründel, 2011 † (basis of record)
Angystoma Schumacher, 1817 accepted as Ringicella Gray, 1847 (source of synonymy)
Angystoma Schumacher, 1817 accepted as Ringicella Gray, 1847 (verified source for family)
Anisopsis Zilch, 1959 † accepted as Liangulorbis Wenz, 1947 † (basis of record)
Anisopsis Zilch, 1959 † accepted as Liangulorbis Wenz, 1947 † (source of synonymy)
Annuliconcha Newell, 1937 † (verified source for family)
Anostoma Fischer, 1807 (verified source for family)
Anostomopsidae Nordsieck, 1986 † (basis of record)
Anostomopsis Sandberger, 1871 (verified source for family)
Antiquamitra Huang & Lin, 2026 † (basis of record)
Antiquamitridae Huang & Lin, 2026 † (basis of record)
Antiquamitridae Huang & Lin, 2026 † (taxonomy source)
Aralina Tsatsir, 1970 (verified source for family)
Aralina Tsatsir, 1970 (basis of record)
Archaeoplanorbis Yu in Guo, Yu & Pan, 1982 † (current name source)
Archaeoplanorbis Yu in Guo, Yu & Pan, 1982 † (verified source for family)
Archaeoplanorbis Yu in Guo, Yu & Pan, 1982 † (basis of record)
Archanodon Howse, 1878 † (verified source for family)
Archanodon Howse, 1878 † (current name source)
Archinacellopsis Horný, 1995 † (current name source)
Architeuthidae Pfeffer, 1900 (taxonomy source)
Arcitalitrus Hurley, 1975 (verified source for family)
Argeneuthria Pastorino, 2016 (verified source for family)
Aristerospira Ehrenberg, 1858 (status source)
Armenocerithium Egoyan, 1955 † (verified source for family)
Armenocerithium Egoyan, 1955 † (current name source)
Arpolyphragmoum Rhumbler, 1913 † accepted as Coscinophragma Thalmann, 1951 † (source of synonymy)
Arribazona Kues, 1990 † (verified source for family)
Ascopariidae Sterrer, 1998 (basis of record)
Ascorhynchidae Hoek, 1881 (basis of record)
Ashrafiella Ilina in Nevesskaya et al., 1986 † accepted as Bogatschevia Ali-Zade & Kabakova in Ali-Zade, 1969 † (source of synonymy)
Asperosculptura Ardovini, Poppe & Tagaro, 2021 (basis of record)
Asterocyclina Gümbel, 1870 † (verified source for family)
Asthenodonta Whiteaves, 1894 † (verified source for family)
Asthenodonta Whiteaves, 1894 † (current name source)
Astrosphaeridae Haeckel, 1881 † (habitat flag source)
Aulacolambrus Paul'son, 1875 (habitat flag source)
Aulacophaedusa Habe, 1958 accepted as Megalophaedusa Böttger, 1877 (source of synonymy)
Auricullina Vassiljeva, 1998 (basis of record)
Auricullina Vassiljeva, 1998 (current name source)
Auricullina Vassiljeva, 1998 (verified source for family)
Auriniopsis Clench, 1953 accepted as Aurinia H. Adams & A. Adams, 1853 accepted as Scaphella Swainson, 1832 (source of synonymy)
Australaraea Rowlett, 2020 accepted as Coscinaraea Milne Edwards & Haime, 1848 (verified source for family)
Australaraea Rowlett, 2020 accepted as Coscinaraea Milne Edwards & Haime, 1848 (source of synonymy)
Australopsammia Rowlett, 2020 accepted as Tubastraea Lesson, 1829 (source of synonymy)
Australopsammia Rowlett, 2020 accepted as Tubastraea Lesson, 1829 (verified source for family)
Austrotroides Friend, 1982 (verified source for family)
Avardaria Kolesnikov, 1950 † (current name source)
Avardaria Kolesnikov, 1950 † (basis of record)
Axiola Luther, 1955 (verified source for family)
Azadinium Elbrächter & Tillmann, 2009 (habitat flag source)
Azadinium Elbrächter & Tillmann, 2009 (extant flag source)
Azeridacna Sultanov, 1963 † accepted as Turcmena Popov, 1956 † (basis of record)
Azeridacna Sultanov, 1963 † accepted as Turcmena Popov, 1956 † (source of synonymy)

 Taxonomic remark

 for Aktschagylia Starobogatov, 1970

replacement name for Mactra Ali-Zade, 1967 (nec Linnaeus, 1767) [details]

 Taxonomic remark

 for Scolodens Baker, 1956

replacement name for Stenopus Guilding, 1828 (nec Latreille, 1819)  [details]