Abas wittii (Grunow) R.Ross & P.A.Sims, 1980 †
Acanthoceras azoricum (Menegh.) Kütz., 1862 accepted as Ceramium azoricum Meneghini accepted as Ceramium echionotum var. azoricum (Meneghini) Piccone, 1884
Acanthoceras echinophorum (Menegh.) Frauenf., 1855 accepted as Ceramium echionotum J.Agardh, 1844
Acanthoceras echionotum (J.Agardh) Kütz., 1849 accepted as Ceramium echionotum J.Agardh, 1844
Acanthoceras magdeburgense Honigm., 1910 accepted as Acanthoceras zachariasii (Brun) Simonsen, 1979
Acanthoceras magdeburgense var. lata Honigm., 1909 accepted as Acanthoceras zachariasii (Brun) Simonsen, 1979
Acanthoceras magdeburgense var. magdeburgense Honigmann, 1909 accepted as Acanthoceras magdeburgense Honigm., 1910 accepted as Acanthoceras zachariasii (Brun) Simonsen, 1979
Acanthoceras oxyacanthum Kützing, 1849 (uncertain )
Acanthoceras zachariasii (Brun) Simonsen, 1979
Actinocyclus abundans Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus acanthus Bradbury & Krebs, 1982 † (uncertain > unassessed )
Actinocyclus acharnar Ehrenberg, 1840 (uncertain > unassessed )
Actinocyclus acharneus Ralfs in Pritchard, 1861 (uncertain > unassessed )
Actinocyclus achates Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus actinochilus (Ehrenberg) Simonsen, 1982 accepted as Coscinodiscus actinochilus Ehrenberg, 1844
Actinocyclus adamas Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus adeliae Manguin, 1957 (uncertain > unassessed )
Actinocyclus aeschylus Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus africanus Leuduger-Fortmorel, 1898 (uncertain > unassessed )
Actinocyclus aldebaran Ehrenberg, 1843 (uncertain > unassessed )
Actinocyclus alexander Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus alienus Grunow in Cleve, 1883 (uncertain > unassessed )
Actinocyclus alienus var. alienus Grunow in Van Heurck, 1883 (uncertain > unassessed )
Actinocyclus alienus var. arctica Grunow in Van Heurck, 1883 (uncertain > unassessed )
Actinocyclus alienus var. californica Grunow in Van Heurck, 1883 (uncertain > unassessed )
Actinocyclus alienus var. undatus Cleve, 1885 (uncertain > unassessed )
Actinocyclus allinearius Hanna & Grant, 1926 (uncertain > unassessed )
Actinocyclus americanus M. Peragallo in Tempère & Peragallo, 1908 (uncertain > unassessed )
Actinocyclus amethystus Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus anacreon Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus anceps Castracane, 1886 (uncertain > unassessed )
Actinocyclus anceps Leuduger-Fortmorel, 1879 (uncertain > unassessed )
Actinocyclus ancorifer Schumann, 1867 (uncertain > unassessed )
Actinocyclus antarcticus Castracane, 1886 (uncertain > unassessed )
Actinocyclus antarcticus Karsten, 1905 (uncertain > unassessed )
Actinocyclus antares Ehrenberg, 1840 (uncertain > unassessed )
Actinocyclus apelles Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus apollo Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus appendiculatus Rattray, 1890 (uncertain > unassessed )
Actinocyclus aquila Ehrenberg, 1840 (uncertain > unassessed )
Actinocyclus arcturus Ehrenberg, 1843 (uncertain > unassessed )
Actinocyclus arcuatus Schumann, 1867 (uncertain > unassessed )
Actinocyclus areolatus (Ehrenberg) Brightwell, 1860 accepted as Omphalopelta areolata Ehrenberg, 1844
Actinocyclus armatus Cleve-Euler, 1941 (uncertain > unassessed )
Actinocyclus asiaticus F.Meister, 1932 (uncertain > unassessed )
Actinocyclus asteriscus (J.A. Barron) Cong Wu, D.M. Williams, Zhiyuan Peng & Chixin Chen, 2022 †
Actinocyclus astroites Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus astrolites Ralfs in Pritchard, 1861 (uncertain > unassessed )
Actinocyclus atlanticus Müller-Melchers, 1959 (uncertain > unassessed )
Actinocyclus australis Grunow in Van Heurck, 1883 (uncertain > unassessed )
Actinocyclus baicalensis G.K. Khursevich & S.A. Fedenya, 2006 (uncertain > unassessed )
Actinocyclus barkleyi Coates, 1861 (uncertain > unassessed )
Actinocyclus barkleyi Grunow
Actinocyclus barkleyi f. barklyi (Coates) Kitton, 1878 accepted as Coscinodiscus barklyi Coates, 1861
Actinocyclus barkleyi f. minor Frenguelli, 1928 (uncertain > unassessed )
Actinocyclus barkleyi var. aggregata Rattray, 1890 (uncertain > unassessed )
Actinocyclus beaufortianus (Hustedt) Sullivan, 1983 accepted as Cosmiodiscus beaufortianus Hustedt, 1955 †
Actinocyclus beryllus Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus betegose Ehrenberg, 1840 (uncertain > unassessed )
Actinocyclus bet-el-gose Ralfs in Pritchard, 1861 (uncertain > unassessed )
Actinocyclus bias Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus bifrons (Castracane) Mann, 1937 accepted as Coscinodiscus bifrons Castracane, 1886 accepted as Charcotiella bifrons (Castrac.) S.Blanco & C.E.Wetzel, 2016
Actinocyclus bifrons Karsten, 1905 (uncertain > unassessed )
Actinocyclus binonarius Ehrenberg, 1854 (uncertain > unassessed )
Actinocyclus bioctonarius Ehrenberg, 1840 (uncertain > unassessed )
Actinocyclus bipartitus Mann, 1925 (uncertain > unassessed )
Actinocyclus bisenarius Ehrenberg, 1840 (uncertain > unassessed )
Actinocyclus biseptenarius Ehrenberg, 1840 (uncertain > unassessed )
Actinocyclus biternarius Ehrenberg, 1840 (uncertain > unassessed )
Actinocyclus boryanus Pantocsek, 1889 (uncertain > unassessed )
Actinocyclus bradburyii T.Hayash, M.Saito-Kato & Y.Tanimura, 2012 †
Actinocyclus brasiliensis Müller-Melchers, 1957 (uncertain > unassessed )
Actinocyclus bremianus Pantocsek, 1889 (uncertain > unassessed )
Actinocyclus calix Tempère & Brun in Brun & Tempère, 1889 (uncertain > unassessed )
Actinocyclus callimachus Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus canestrus Hanna & Grant, 1926 (uncertain > unassessed )
Actinocyclus canopus Ehrenberg, 1840 (uncertain > unassessed )
Actinocyclus capella Ehrenberg, 1840 (uncertain > unassessed )
Actinocyclus carbunculus Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus caspicus (Makarova) Makarova, 1985 accepted as Thalassiosira caspica Makarova, 1959
Actinocyclus cedrus Bradbury & Krebs, 1982 † (uncertain > unassessed )
Actinocyclus ceres Ehrenberg, 1840 (uncertain > unassessed )
Actinocyclus challengeri O'Meara, 1876 (uncertain > unassessed )
Actinocyclus chilo Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus cholnokyi VanLandingham, 1967 (uncertain > unassessed )
Actinocyclus chrysolithus Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus circellus T.P.Watkins, 1986 (uncertain > unassessed )
Actinocyclus circumdatus Pantocsek, 1886 (uncertain > unassessed )
Actinocyclus clavifer Schumann, 1867 (uncertain > unassessed )
Actinocyclus claviolus Bradbury & Krebs, 1982 (uncertain > unassessed )
Actinocyclus cleobulus Ehrenberg, 1845 (uncertain > unassessed )
Actinocyclus clevei Castracane, 1886 (uncertain > unassessed )
Actinocyclus complanatus F.S.Castracane degli Antelminelli
Actinocyclus complanatus var. anguste-fasciata Rattray, 1890 (uncertain > unassessed )
Actinocyclus complanatus var. complanatus Castracane, 1886 (uncertain > unassessed )
Actinocyclus complanatus var. late-fasciata Rattray, 1890 (uncertain > unassessed )
Actinocyclus concentricus Rattray, 1890 (uncertain > unassessed )
Actinocyclus confluens Grunow, 1890
Actinocyclus confluens var. appiculata Rattray, 1890 (uncertain > unassessed )
Actinocyclus confluens var. confluens Grunow in Rattray, 1890 (uncertain > unassessed )