Acanthocythereis Howe, 1963 (additional source)
Acantholaimus Allgén, 1933 (additional source)
Acanthostepheia Boeck, 1871 (additional source)
Acanthozone Boeck, 1871 accepted as Paramphithoe Bruzelius, 1859 (additional source)
Acaulis Stimpson, 1853 (additional source)
Aceroides G.O. Sars, 1892 (additional source)
Acetabulastoma Schornikov, 1970 (additional source)
Achelia Hodge, 1864 (additional source)
Acineta Ehrenberg, 1834 (additional source)
Acrorhynchides Strand, 1928 (additional source)
Acryptolaria Norman, 1875 (additional source)
Actinocythereis Puri, 1953 (additional source)
Actinoposthia An der Lan, 1936 (additional source)
Actinostola Verrill, 1883 (additional source)
Adercotryma Loeblich & Tappan, 1952 (additional source)
Adoncholaimus Filipjev, 1918 (additional source)
Aegialoalaimus de Man, 1907 (additional source)
Aeginina Norman, 1905 (additional source)
Aeginopsis Brandt, 1835 (additional source)
Alaurina Busch, 1851 accepted as Microstomum Schmidt, 1848 (additional source)
Alca Linnaeus, 1758 (additional source)
Alle Link, 1806 (additional source)
Allocyttus McCulloch, 1914 (additional source)
Altenaeum Spaink, 1972 (additional source)
Alveolophragmium Shchedrina, 1936 (basis of record)
Amage Malmgren, 1866 (additional source)
Amallophora Scott T., 1894 accepted as Xanthocalanus Giesbrecht, 1893 (additional source)
Amathillopsis Heller, 1875 (additional source)
Ambasia Boeck, 1871 (additional source)
Ambasiella Schellenberg, 1935 (additional source)
Ammobaculites Cushman, 1910 (additional source)
Ammodiscus Reuss, 1862 (additional source)
Ammoglobigerina Eimer & Fickert, 1899 (additional source)
Ammolagena Eimer & Fickert, 1899 (additional source)
Ammopemphix Loeblich, 1952 (additional source)
Ammotium Loeblich & Tappan, 1953 (additional source)
Amphicteis Grube, 1850 (additional source)
Amphilochella Schellenberg, 1926 (additional source)
Amphilochopsis Stephensen, 1925 accepted as Amphilochus Spence Bate, 1863 (additional source)
Amphiodia Verrill, 1899 (additional source)
Andaniella G.O. Sars, 1891 accepted as Andaniopsis G.O. Sars, 1891 (additional source)
Andaniexis Stebbing, 1906 (additional source)
Anisarchus Gill, 1864 (additional source)
Anobothrus Levinsen, 1884 (additional source)
Anoplodium Schneider, 1858 (additional source)
Anoplostoma Bütschli, 1874 (additional source)
Antholoba Hertwig, 1882 (additional source)
Anthosactis Danielssen, 1890 (additional source)
Anticoma Bastian, 1865 (additional source)
Antimora Günther, 1878 (additional source)
Aphanostoma Ørsted, 1845 (additional source)
Arachnoidea Moore, 1903 (additional source)
Araeolaimus de Man, 1888 (additional source)
Archaphanostoma Dörjes, 1968 accepted as Baltalimania Ax, 1959 (additional source)
Arctogadus Dryagin, 1932 (additional source)
Arctolembos Myers, 1979 (additional source)
Arctonula Gordon & Grischenko, 1994 (additional source)
Arctozenus Gill, 1864 (additional source)
Arenotrocha Westheide & von Nordheim, 1985 (additional source)
Argentina Linnaeus, 1758 (additional source)
Argilloecia Sars, 1866 (additional source)
Argis Krøyer, 1843 (additional source)
Argyropelecus Cocco, 1829 (additional source)
Aristias Boeck, 1871 (additional source)
Arrhinopsis Stappers, 1911 (additional source)
Artediellus Jordan, 1885 (additional source)
Arthropsyllus Sars G.O., 1909 (additional source)
Asabellides Annenkova, 1929 accepted as Ampharete Malmgren, 1866 (additional source)
Aschemonella Brady, 1879 (additional source)
Ascolaimus Ditlevsen, 1919 (additional source)
Aspidoconcha De Vos, 1953 (additional source)
Astrononion Cushman & Edwards, 1937 (additional source)
Astrorhiza Sandahl, 1858 (additional source)
Astrotorhynchus Graff, 1905 (additional source)
Astyra Boeck, 1871 (additional source)
Atolla Haeckel, 1880 (additional source)
Atrochromadora Wieser, 1959 (additional source)
Atrophia Huys & Böttger-Schnack, 1997 (additional source)
Augaptilus Giesbrecht, 1889 (additional source)
Aulactinia Agassiz in Verrill, 1864 (additional source)
Austrosyrrhoe K.H. Barnard, 1925 (additional source)
Axinella Schmidt, 1862 (additional source)
Axonolaimus de Man, 1889 (additional source)
Baffinia Wesenberg-Lund, 1950 (additional source)
Baffinicythere Hazel, 1967 (additional source)
Baicalellia Nasonov, 1930 (additional source)
Balbidocolon Hessler, 1970 (additional source)
Baltalimania Ax, 1959 (additional source)
Balticina Gray, 1870 (additional source)
Barbonema Filipjev, 1927 (additional source)
Barrowgammarus Bousfield, 1979 (additional source)
Baseodiscus Diesing, 1850 (additional source)
Bathyfauvelia Pettibone, 1976 (additional source)
Bathylagus Günther, 1878 (additional source)
Bathypolypus Grimpe, 1921 (additional source)
Bathysiphon Sars, 1872 (additional source)
Bathysoecia Osburn, 1953 (basis of record)
Benthalbella Zugmayer, 1911 (additional source)
Benthosema Goode & Bean, 1896 (additional source)
Bolivina d'Orbigny, 1839 (additional source)