Abas R.Ross & P.A.Sims, 1980 † (basis of record)
Abas wittii (Grunow) R.Ross & P.A.Sims, 1980 † (basis of record)
Acanthoceras Honigm., 1910 (additional source)
Acanthoceras zachariasii (Brun) Simonsen, 1979 (additional source)
Acanthodiscus Pant., 1892 † (basis of record)
Acanthodiscus antarcticus Hajós, 1975 † (additional source)
Acanthodiscus clypeolus (Brun) Van Heurck, 1896 † (additional source)
Acanthodiscus convexus Hajós & Stradner in Hajós, 1975 † (additional source)
Acanthodiscus danicus J.Fenner, 1994 † (basis of record)
Acanthodiscus immaculatus (Hanna) V.A.Nikolaev & J.A.Barron in Nikolaev et al., 2001 † (additional source)
Acanthodiscus ornatus Hajós & Stradner in Hajós, 1975 † (additional source)
Acanthodiscus paterus (J.A.Long, Fuge & J.Smith) V.A.Nikolajev & Fourt. † (basis of record)
Acanthodiscus rugosus Pant., 1892 † (additional source)
Acanthodiscus schmidtii Jousé, 1951 † (additional source)
Acanthodiscus vulcaniformis Jousé, 1951 † (additional source)
Achnantheiopsis Lange-Bert., 1997 accepted as Planothidium F.E. Round & L. Bukhtiyarova, 1996 (basis of record)
Achnantheiopsis Lange-Bert., 1997 accepted as Planothidium F.E. Round & L. Bukhtiyarova, 1996 (status source)
Achnantheiopsis borneolanceolata Lange-Bert., 1997 accepted as  (basis of record)
Achnanthepyla Perag., 1921 (basis of record)
Achnanthepyla baccata Perag., 1921 (basis of record)
Achnanthepyla bongrainii Perag., 1921 accepted as Achnanthes bongrainii (M. Peragallo) Mann, 1937 accepted as Achnanthepyla bongrainii var. bongrainii Perag., 1921 (basis of record)
Achnanthepyla bongrainii var. bongrainii Perag., 1921 accepted as Achnanthepyla bongrainii Perag., 1921 accepted as Achnanthes bongrainii (M. Peragallo) Mann, 1937 (basis of record)
Achnanthepyla gainii accepted as Achnanthepyla gainii var. gainii Perag., 1921 accepted as Achnanthes gainii (M. Peragallo) Mann, 1937 (basis of record)
Achnanthepyla gainii var. gainii Perag., 1921 accepted as Achnanthes gainii (M. Peragallo) Mann, 1937 (basis of record)
Achnanthepyla gainii var. ostrupii Perag., 1921 (basis of record)
Achnanthepyla glabrata (Grunow) Perag., 1921 (basis of record)
Achnanthepyla glabrata var. aucklandica (Grunow in Cleve & Grunow) Perag., 1921 (basis of record)
Achnanthepyla glabrata var. glabrata (Grunow) Perag., 1921 accepted as Achnanthepyla glabrata (Grunow) Perag., 1921 (basis of record)
Achnanthepyla mesogongyla (Grunow in Cleve & Grunow) Perag., 1921 (basis of record)
Achnanthepyla minuta ‘(Grunow) M. Peragallo' VanLandingham, 1967 accepted as Achnanthepyla minutula (Grunow) Perag., 1921 (basis of record)
Achnanthepyla minutula (Grunow) Perag., 1921 (basis of record)
Achnanthepyla simplex Perag., 1921 (basis of record)
Achnanthes Bory, 1822 (additional source)
Achnanthes acares M.H.Hohn & Hellerman, 1963 (basis of record)
Achnanthes acus Simonsen ex F.Hinz et al., 2012 (basis of record)
Achnanthes acuta Frenguelli, 1953 (basis of record)
Achnanthes adamsii Cholnoky, 1964 (basis of record)
Achnanthes adnata Bory, 1822 (basis of record)
Achnanthes affinis Grunow, 1880 accepted as Achnanthidium affine (Grunow) Czarnecki, 1994 accepted as Achnanthes affinis var. affinis Grunow in Cleve & Grunow, 1880 (additional source)
Achnanthes affinis var. affinis Grunow in Cleve & Grunow, 1880 accepted as Achnanthes affinis Grunow, 1880 accepted as Achnanthidium affine (Grunow) Czarnecki, 1994 (basis of record)
Achnanthes africana Woodhead & Tweed, 1958 (basis of record)
Achnanthes agglutinata Grunow in Cleve & Grunow, 1880 (basis of record)
Achnanthes alteragracillima Lange-Bert., 1993 accepted as Achnanthidium gracillimum (Meister) Lange-Bertalot, 2004 accepted as Microneis gracillima Meister, 1912 (basis of record)
Achnanthes ambigua S.J.C.Zimmermann, 1918 (basis of record)
Achnanthes americana Cleve, 1893 (basis of record)
Achnanthes amoena Hust., 1952 accepted as Karayevia amoena (Hust.) Bukht., 2006 (basis of record)
Achnanthes amphicephala Hust., 1939 (additional source)
Achnanthes anceps A.Cleve, 1934 (basis of record)
Achnanthes angustata Grev., 1859 (basis of record)
Achnanthes annulifera A.Cleve, 1953 (basis of record)
Achnanthes antarctica Perag., 1921 (basis of record)
Achnanthes antiqua Lauby, 1910 † (basis of record)
Achnanthes aperta J.R.Carter, 1981 accepted as Skabitschewskia aperta (Carter) Kulikovskiy & Lange-Bertalot, 2015 (additional source)
Achnanthes araucaniana Freng., 1934 † (additional source)
Achnanthes archibaldiana Lange-Bert., 1989 accepted as Rossithidium archibaldianum (Lange-Bertalot) L.N.Bukhtiyarova, 2008 (basis of record)
Achnanthes arctica (Cleve) A.Cleve, 1915 accepted as Achnanthes brevipes var. arctica (P. T. Cleve) T. Ko-Bayashi, 1965 accepted as Achnanthidium arcticum Cleve, 1873 (basis of record)
Achnanthes arcuata (Lyngb.) Kütz., 1833 (basis of record)
Achnanthes arenaria Amossé, 1941 (additional source)
Achnanthes arenicola J.W.Bailey, 1851 (basis of record)
Achnanthes arguta Hust.ex Simonsen, 1987 (basis of record)
Achnanthes astridii VanLand., 1967 (basis of record)
Achnanthes asymbasia M.H.Hohn, 1966 (basis of record)
Achnanthes asymetrica R.M.Patrick, 1936 (basis of record)
Achnanthes atacamae Hust., 1927 (additional source)
Achnanthes athenais Pant., 1902 † (basis of record)
Achnanthes athenais var. athenais Pant., 1902 accepted as Achnanthes athenais Pant., 1902 † (basis of record)
Achnanthes athenais var. minor Pant., 1902 † (basis of record)
Achnanthes atomus Hust., 1937 accepted as Achnanthidium atomus (Hustedt) Monnier, Lange-Bertalot & Ector in Monnier et al., 2004 accepted as Achnanthes atomus var. atomus Hust., 1937 (additional source)
Achnanthes atomus var. atomus Hust., 1937 accepted as Achnanthes atomus Hust., 1937 accepted as Achnanthidium atomus (Hustedt) Monnier, Lange-Bertalot & Ector in Monnier et al., 2004 (basis of record)
Achnanthes aueri Krasske, 1949 † accepted as Planothidium aueri (Krasske) H. Lange-Bertalot, 1999 (basis of record)
Achnanthes australis Ehrenb., 1854 (basis of record)
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 (additional source)
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 (additional source)
Achnanthes austriaca var. helvetica Hust., 1933 accepted as Psammothidium helveticum (Hustedt) L.N.Bukhtiyarova & Round, 1996 (additional source)
Achnanthes baccata (Leud.-Fortm.) Cleve, 1895 (basis of record)
Achnanthes bacescui Bodeanu, 1976 (basis of record)
Achnanthes bacillaris Ehrenberg, 1844 (basis of record)
Achnanthes bacillum Perag. in Héribaud et al., 1920 (basis of record)
Achnanthes baicalensis Skvortsov & Meyer, 1928 accepted as Planothidium baicalense (Skvortzow & K.I. Meyer) M.B. Edlund in M.B. Edlund, N. Soninkhishig, R.M. Williams & E.F. Stoermer, 2001 (additional source)
Achnanthes baicaliana var. baicaliana Freng., 1953 accepted as Achnanthes baicaliana Frenguelli, 1953 (basis of record)
Achnanthes baicaliana var. notata Frenguelli, 1953 (basis of record)
Achnanthes baldjicki sensu Pantocsek, 1892 † (basis of record)
Achnanthes baldjicki (Brightw.) Grunow † accepted as Rhaphoneis baldjikii (Brightwell) Grunow, 1862 accepted as Odontidium baldjicki Brightwell, 1859 (basis of record)
Achnanthes baldjicki var. subquadrata Pant., 1892 † (basis of record)
Achnanthes bavarica Ehrenb., 1853 (basis of record)
Achnanthes bengalensis Grunow in Cleve & Grunow, 1880 (additional source)
Achnanthes bengalensis var. bengalensis Grunow in Cleve & Grunow, 1880 accepted as Achnanthes bengalensis Grunow in Cleve & Grunow, 1880 (basis of record)
Achnanthes bengalensis var. subventricosa Grunow in Cleve & Grunow, 1880 (basis of record)
Achnanthes bergii A.Cleve, 1953 (basis of record)
Achnanthes bernieri Manguin ex Kociolek & de Reviers, 1996 (basis of record)
Achnanthes biasolettiana Grunow, 1880 accepted as Achnanthidium pyrenaicum (Hustedt) H.Kobayasi, 1997 accepted as Achnanthes pyrenaica var. pyrenaica Hustedt, 1939 (additional source)
Achnanthes biasolettiana var. biasolettiana Grunow accepted as Achnanthes biasolettiana Grunow, 1880 accepted as Achnanthidium pyrenaicum (Hustedt) H.Kobayasi, 1997 accepted as Achnanthes pyrenaica var. pyrenaica Hustedt, 1939 (basis of record)
Achnanthes biasolettiana var. sublinearis Grunow ex Van Heurck (basis of record)
Achnanthes bicapitellata Cleve-Euler, 1953 (basis of record)
Achnanthes biceps Hustedt, 1959 (basis of record)
Achnanthes biconfusa VanLandingham, 1967 accepted as Nupela biconfusa (VanLandingham) C.E.Wetzel & Ector, 2018 (basis of record)
Achnanthes bigibba Heiden in Heiden & Kolbe, 1928 (basis of record)
Achnanthes bijuga Turpin, 1828 (basis of record)
Achnanthes bijugata Polenov, 1918 (basis of record)
Achnanthes bilunulata Turpin, 1828 (basis of record)