Acanthocystis paliformis Durrschmidt, 1987
Acanthocystis perpusilla Petersen & Hansen, 1960
Acanthocystis turfacea Carter, 1863
Acanthoica quattrospina Lohmann, 1903
Acanthostomella norvegica (Daday, 1887)
Achnanthepyla gainii accepted as Achnanthepyla gainii var. gainii Perag., 1921 accepted as Achnanthes gainii (M. Peragallo) Mann, 1937
Achnanthepyla gainii var. gainii Perag., 1921 accepted as Achnanthes gainii (M. Peragallo) Mann, 1937
Achnanthes abundans Manguin in Bourrelly & Manguin, 1954 accepted as Psammothidium abundans (Manguin, Bourrelly & Manguin) L.Bukhtiyarova, 1996
Achnanthes abundans var. abundans Manguin in Bourrelly & Manguin, 1955 accepted as Achnanthes abundans Manguin in Bourrelly & Manguin, 1954 accepted as Psammothidium abundans (Manguin, Bourrelly & Manguin) L.Bukhtiyarova, 1996
Achnanthes austriaca Hust., 1922 accepted as Eucocconeis austriaca (Hustedt) H. Lange-Bertalot apud H. Lange-Bertalot & S.I. Genkal in H. Lange-Bertalot (ed.), 1999 accepted as Achnanthes austriaca var. austriaca Hust., 1922
Achnanthes austriaca var. austriaca Hust., 1922 accepted as Achnanthes austriaca Hust., 1922 accepted as Eucocconeis austriaca (Hustedt) H. Lange-Bertalot apud H. Lange-Bertalot & S.I. Genkal in H. Lange-Bertalot (ed.), 1999
Achnanthes brevipes C.Agardh, 1824
Achnanthes brevipes Kützing, 1833 (uncertain > unassessed )
Achnanthes brevipes var. arctica (P. T. Cleve) T. Ko-Bayashi, 1965 accepted as Achnanthidium arcticum Cleve, 1873
Achnanthes brevipes var. intermedia (Kützing) Cleve, 1895 accepted as Achnanthes intermedia Kützing, 1833
Achnanthes chlidanos M.H.Hohn & Hellerman, 1963 (uncertain > unassessed )
Achnanthes clevei Grunow, 1880 accepted as Karayevia clevei (Grunow) Round & Bukhtiyarova, 1999
Achnanthes coarctata (Brébisson ex W.Smith) Grunow, 1880
Achnanthes coarctata var. elliptica Krasske, 1929 (uncertain > unassessed )
Achnanthes confusa Manguin
Achnanthes conspicua A.Mayer, 1919 accepted as Planothidium conspicuum (A.Mayer) M.Aboal, 2003 accepted as Achnanthes conspicua var. conspicua A.Mayer, 1919
Achnanthes conspicua var. conspicua A.Mayer, 1919 (uncertain > unassessed )
Achnanthes delicatula (Kützing) Brun, 1880 accepted as Achnanthidium delicatulum f. delicatulum Kützing, 1844
Achnanthes engelbrechtii Cholnoky, 1955 accepted as Planothidium engelbrechtii (Cholnoky) Round & L.Bukhtiyarova, 1996 accepted as Achnanthes engelbrechtii var. engelbrechtii Cholnoky, 1955
Achnanthes engelbrechtii var. engelbrechtii Cholnoky, 1955 (uncertain > unassessed )
Achnanthes exilis Kützing, 1833 accepted as Achnanthidium exile (Kützing) Heiberg, 1863 accepted as Achnanthes exilis var. exilis Kützing, 1833
Achnanthes exilis sensu W. Smith, 1856 (uncertain > unassessed )
Achnanthes exilis var. exilis Kützing, 1833 (uncertain > unassessed )
Achnanthes exilis var. minutissima Brun, 1880 (uncertain > unassessed )
Achnanthes gainii (M. Peragallo) Mann, 1937
Achnanthes germainii Manguin in Bourrelly & Manguin, 1954 (uncertain > unassessed )
Achnanthes groenlandica (Cleve) Grunow, 1880 (uncertain > unassessed )
Achnanthes hauckiana Grunow, 1880 (uncertain > unassessed )
Achnanthes hauckiana var. hauckiana Grunow in Cleve & Grunow, 1880 (uncertain > unassessed )
Achnanthes hungarica (Grunow) Grunow, 1880 accepted as Lemnicola hungarica (Grunow) F.E.Round & P.W.Basson, 1997 accepted as Achnanthidium hungaricum Grunow, 1863
Achnanthes inflata (Kützing) Grunow, 1867
Achnanthes intermedia Kützing, 1833 (uncertain > unassessed )
Achnanthes kryophila J.B.Petersen, 1924 accepted as Achnanthes chlidanos M.H.Hohn & Hellerman, 1963
Achnanthes lanceolata (Brébisson ex Kützing) Grunow, 1880 accepted as Planothidium lanceolatum (Brébisson ex Kützing) Bukhtiyarova, 1999
Achnanthes lanceolata (Patrick) Lange-Bertalot, 1993 accepted as Achnanthes lanceolata var. apiculata R.M.Patrick, 1945 accepted as Planothidium apiculatum (Patrick) R.Lowe in Johansen et al., 2004 accepted as Planothidium apiculatum (R.M.Patrick) Lange-Bertalot, 1999
Achnanthes lanceolata var. apiculata R.M.Patrick, 1945 accepted as Planothidium apiculatum (Patrick) R.Lowe in Johansen et al., 2004 accepted as Planothidium apiculatum (R.M.Patrick) Lange-Bertalot, 1999
Achnanthes lapidosa Krasske, 1929 accepted as Nupela lapidosa (Krasske) Lange-Bertalot, 1999
Achnanthes lapidosa var. lapidosa Krasske, 1929 accepted as Nupela lapidosa (Krasske) Lange-Bertalot, 1999
Achnanthes lapponica (Hustedt) Hustedt, 1933 accepted as Eucocconeis quadratarea (Østrup) Lange-Bertalot, 1999
Achnanthes linearis (W.Smith) Grunow, 1880 accepted as Achnanthidium lineare W.Smith, 1855
Achnanthes manguinii Hustedt
Achnanthes marginulata Grunow, 1880
Achnanthes marginulata var. marginulata Grunow in Cleve & Grunow, 1880 (uncertain > unassessed )
Achnanthes metakryophila Lange-Bertalot & Schmidt, 1990 (uncertain > unassessed )
Achnanthes minutissima Kützing, 1833 (uncertain > unassessed )
Achnanthes minutissima var. cryptocephala Grunow, 1880 (uncertain > unassessed )
Achnanthes minutissima var. minutissima Kützing, 1833 (uncertain > unassessed )
Achnanthes modesta Manguin in Bourrelly & Manguin, 1954 accepted as Achnanthidium modestiforme (Lange-Bert.) Van de Vijver in Van de Vijver et al., 2002
Achnanthes montana Krasske, 1929 accepted as Psammothidium montanum (Krasske) Mayuma, 2002 accepted as Achnanthes montana var. montana Krasske, 1929
Achnanthes montana var. montana Krasske, 1929 (uncertain > unassessed )
Achnanthes ninckei P.Guermeur & E.Manguin, 1953 (uncertain > unassessed )
Achnanthes nodosa Cleve, 1900 (uncertain > unassessed )
Achnanthes oblongella Østrup, 1902 (uncertain > unassessed )
Achnanthes parvula Kützing, 1836 (uncertain > unassessed )
Achnanthes parvula Kützing, 1844 (uncertain > unassessed )
Achnanthes petersenii Hustedt, 1937
Achnanthes pseudolanceolata Manguin, 1962 (uncertain > unassessed )
Achnanthes saxonica Krasske ex Hustedt, 1933 (uncertain > unassessed )
Achnanthes stauroneioides Manguin in Bourrelly & Manguin, 1954 (uncertain > unassessed )
Achnanthes subatomoides (Hustedt) Lange-Bertalot & Archibald, 1985 accepted as Navicula subatomoides Hustedt, 1936
Achnanthes subsessilis Kützing, 1833 accepted as Achnanthes brevipes var. intermedia (Kützing) Cleve, 1895 accepted as Achnanthes intermedia Kützing, 1833
Achnanthes taylorensis D.E. Kellogg, M. Stuiver, T.B. Kellogg & G.H. DEnton, 1980 (uncertain > unassessed )
Achnanthes vicentii Manguin, 1957 (uncertain > unassessed )
Achnanthidium arcticum Cleve, 1873 (uncertain > unassessed )
Achnanthidium delicatulum sensu Schumann, 1867 (uncertain > unassessed )
Achnanthidium delicatulum f. delicatulum Kützing, 1844 (uncertain > unassessed )
Achnanthidium exile (Kützing) Heiberg, 1863 accepted as Achnanthes exilis var. exilis Kützing, 1833
Achnanthidium hungaricum Grunow, 1863 (uncertain > unassessed )
Achnanthidium lanceolatum Brébisson ex Kützing, 1846 accepted as Planothidium lanceolatum (Brébisson ex Kützing) Bukhtiyarova, 1999
Achnanthidium lanceolatum f. lanceolatum Brébisson ex Kützing, 1846 (uncertain > unassessed )
Achnanthidium lanceolatum f. typica Meister, 1912 (uncertain > unassessed )
Achnanthidium lapidosum (Krasske) Kobayasi, 2002 accepted as Nupela lapidosa (Krasske) Lange-Bertalot, 1999
Achnanthidium lineare W.Smith, 1855 (uncertain > unassessed )
Achnanthidium microcephalum Kützing, 1844 (uncertain > unassessed )
Achnanthidium microcephalum sensu Neupauer, 1867 (uncertain > unassessed )
Achnanthidium minutissimum (Kützing) Czarnecki, 1994 accepted as Achnanthes minutissima var. minutissima Kützing, 1833
Achnanthidium modestiforme (Lange-Bert.) Van de Vijver in Van de Vijver et al., 2002
Achnanthidium subatomoides (Hustedt) O. Monnier, H. Lange-Bertalot & L. Ector in Monnier et al., 2007 accepted as Navicula subatomoides Hustedt, 1936
Acineta grahami Allgin, 1955
Actimonas mirabilis Kent, 1880
Actinocyclus actinochilus (Ehrenberg) Simonsen, 1982 accepted as Coscinodiscus actinochilus Ehrenberg, 1844
Actinocyclus adeliae Manguin, 1957 (uncertain > unassessed )
Actinocyclus asteriscus (J.A. Barron) Cong Wu, D.M. Williams, Zhiyuan Peng & Chixin Chen, 2022 †
Actinocyclus cholnokyi VanLandingham, 1967 (uncertain > unassessed )
Actinocyclus complanatus F.S.Castracane degli Antelminelli
Actinocyclus complanatus var. complanatus Castracane, 1886 (uncertain > unassessed )
Actinocyclus curvatulus Janisch, 1874 (uncertain > unassessed )
Actinocyclus curvulatus
Actinocyclus dimorphus (Castracane) Harwood & Maruyama, 1992 accepted as Coscinodiscus dimorphus Castracane, 1886
Actinocyclus divisus (Grunow) Hustedt, 1958 accepted as Coscinodiscus divisus var. divisus Grunow, 1878
Actinocyclus ehrenbergii Ralfs, 1861
Actinocyclus ehrenbergii Schumann, 1867 (uncertain > unassessed )
Actinocyclus ehrenbergii var. asteriscus Barron, 1975 † represented as Actinocyclus asteriscus (J.A. Barron) Cong Wu, D.M. Williams, Zhiyuan Peng & Chixin Chen, 2022 †
Actinocyclus exiguus G.Fryxell & Semina, 1981 (uncertain > unassessed )
Actinocyclus ingens Rattray, 1890 † (uncertain > unassessed )