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 azoricum (Menegh.) Kütz., 1862 accepted as Ceramium azoricum Meneghini accepted as Ceramium echionotum var. azoricum (Meneghini) Piccone, 1884 (additional source)
Acanthoceras echinophorum (Menegh.) Frauenf., 1855 accepted as Ceramium echionotum J.Agardh, 1844 (additional source)
Acanthoceras echionotum (J.Agardh) Kütz., 1849 accepted as Ceramium echionotum J.Agardh, 1844 (basis of record)
Acanthoceras magdeburgense var. lata Honigm., 1909 accepted as Acanthoceras zachariasii (Brun) Simonsen, 1979 (basis of record)
Acanthoceras magdeburgense var. magdeburgense Honigmann, 1909 accepted as Acanthoceras magdeburgense Honigm., 1910 accepted as Acanthoceras zachariasii (Brun) Simonsen, 1979 (basis of record)
Acanthoceras oxyacanthum Kützing, 1849 (additional source)
Acanthoceras shuttleworthianum Kützing, 1842 accepted as Ceramium shuttleworthianum (Kützing) Rabenhorst, 1847 (additional source)
Acanthoceras shuttleworthianum var. breviarticulatum Kützing, 1862 (basis of record)
Acanthoceras shuttleworthianum var. longiarticulatum Kützing, 1862 (basis of record)
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)
Achnantella Gaillon, 1833 accepted as Achnanthes Bory, 1822 (basis of record)
Achnantella brevipes (C.Agardh) Gaillon, 1833 accepted as Achnanthes brevipes C.Agardh, 1824 (basis of record)
Achnantella longipes (C.Agardh) Gaillon, 1833 accepted as Achnanthes longipes C.Agardh, 1824 (basis of record)
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 apiculata (R.M.Patrick) Lange-Bert., 1997 accepted as Planothidium apiculatum (R.M.Patrick) Lange-Bertalot, 1999 (basis of record)
Achnantheiopsis aueri (Krasske) Lange-Bert., 1997 † accepted as  † (basis of record)
Achnantheiopsis biporoma (M.H.Hohn & Hellerman) Lange-Bertalot, 1997 accepted as Planothidium biporomum (M.H.Hohn & Hellerman) Lange-Bertalot, 1999 (basis of record)
Achnantheiopsis borneolanceolata Lange-Bert., 1997 accepted as  (basis of record)
Achnantheiopsis chilensis (Hust.) Lange-Bert., 1997 † accepted as Planothidium chilense (Hustedt) Lange-Bertalot, 1999 † accepted as Achnanthes chilensis Hustedt, 1927 † (basis of record)
Achnantheiopsis daui (Foged) Lange-Bert., 1997 accepted as Planothidium daui (Foged) Lange-Bertalot, 1999 accepted as Achnanthes daui Foged, 1962 (basis of record)
Achnantheiopsis delicatula (Kütz.) Lange-Bert., 1997 accepted as Planothidium delicatulum (Kützing) Round & Bukhtiyarova, 1996 accepted as Achnanthidium delicatulum f. delicatulum Kützing, 1844 (basis of record)
Achnantheiopsis distincta (Messik.) Lange-Bert., 1997 accepted as Planothidium distinctum (Messikommer) Lange-Bertalot, 1999 accepted as Achnanthes distincta Messikommer, 1954 (basis of record)
Achnantheiopsis dubia (Grunow) Lange-Bert., 1997 accepted as Planothidium dubium (Grunow) Round & Bukhtiyarova, 1996 (basis of record)
Achnantheiopsis engelbrechtii (Cholnoky) Lange-Berta., 1997 accepted as Planothidium engelbrechtii (Cholnoky) Round & L.Bukhtiyarova, 1996 accepted as Achnanthes engelbrechtii var. engelbrechtii Cholnoky, 1955 (basis of record)
Achnantheiopsis fonticolanceolata (Lange-Bert. & Schim.) Lange-Bert., 1997 accepted as Planothidium fonticolanceolatum (Lange-Bertalot & Schimanski) Lange-Bertalot, 1999 accepted as Achnanthes fonticolanceolata Lange-Bertalot & Schimanski, 1989 (basis of record)
Achnantheiopsis fragilarioides (J.B.Petersen) Lange-Bert., 1997 accepted as Planothidium fragilarioides (J.B.Petersen) Round & Bukhtiyarova, 1996 accepted as Achnanthes fragilarioides J.B.Petersen, 1924 (basis of record)
Achnantheiopsis frequentissima (Lange-Bert.) Lange-Bert., 1997 accepted as Planothidium frequentissimum (Lange-Bertalot) Lange-Bertalot, 1999 (basis of record)
Achnantheiopsis frequentissima var. magna (F.Straub) Lange-Bert., 1997 accepted as Planothidium frequentissimum var. magnum (F.Straub) Lange-Bertalot, 1999 accepted as Achnanthes rostrata var. magna F.Straub, 1985 (basis of record)
Achnantheiopsis frequentissima var. minor (Schulz-Danzig) Lange-Bert., 1997 accepted as Planothidium frequentissimum var. minus (Schulz-Danzig) Lange-Bertalot, 1999 accepted as Achnanthes lanceolata f. minor Schulz, 1926 (basis of record)
Achnantheiopsis grana (M.H.Hohn & Hellerman) Lange-Bert., 1997 accepted as Planothidium granum (M.H.Hohn & Hellerman) Lange-Bertalot, 1999 accepted as Achnanthes grana Hohn & Hellerman, 1963 (basis of record)
Achnantheiopsis hauckiana (Grunow) Lange-Bert., 1997 accepted as Planothidium hauckianum (Grunow) Round & Bukhtiyarova, 1996 (basis of record)
Achnantheiopsis haynaldii (Schaarschm.) Lange-Bert., 1997 accepted as Planothidium haynaldii (Schaarschmidt) Lange-Bertalot, 1999 (basis of record)
Achnantheiopsis heteromorpha (Grunow) Lange-Bert., 1997 accepted as Planothidium heteromorphum (Grunow) Lange-Bertalot, 1999 accepted as Achnanthes heteromorpha var. heteromorpha Grunow in Cleve & Grunow, 1880 (basis of record)
Achnantheiopsis holstii (Cleve) Lange-Bert., 1997 accepted as Planothidium holstii (Cleve) Lange-Bertalot, 1999 accepted as Achnanthes holstii var. holstii Cleve, 1881 (basis of record)
Achnantheiopsis joursacensis (Hérib.) Lange-Bert., 1997 accepted as Planothidium joursacense (Héribaud-Joseph) Lange-Bertalot, 1999 accepted as Achnanthes joursacense Héribaud-Joseph, 1903 (basis of record)
Achnantheiopsis lanceolata (Bréb. ex Kütz.) Lange-Bert., 1997 accepted as Planothidium lanceolatum (Brébisson ex Kützing) Bukhtiyarova, 1999 (basis of record)
Achnantheiopsis lanceolatoides (Sovereign) Lange-Bert., 1997 (basis of record)
Achnantheiopsis linkei (Hustedt) Lange-Bert., 1997 accepted as Planothidium linkei (Hustedt) Lange-Bertalot, 1999 accepted as Achnanthes linkei var. linkei Hustedt, 1939 (basis of record)
Achnantheiopsis magnifica (Hustedt) Lange-Bert., 1997 accepted as Planothidium magnificum (Hustedt) Lange-Bertalot, 1999 accepted as Achnanthes magnifica Hustedt, 1952 (basis of record)
Achnantheiopsis marina (Hust.) Lange-Bertalot, 1997 accepted as Planothidium marinum (Hustedt) Lange-Bertalot, 1999 accepted as Achnanthes marina Hustedt, 1937 (basis of record)
Achnantheiopsis minutissima (Krasske) Lange-Bert., 1997 accepted as Achnanthes lanceolata var. minutissima Krasske, 1938 accepted as Planothidium minutissimum (Krasske) Lange-Bertalot, 1999 (basis of record)
Achnantheiopsis miota (J.R.Carter & Denny) Lange-Bert., 1997 accepted as Planothidium miotum (Carter & Denny) Lange-Bertalot, 1999 accepted as Achnanthes miota Carter & Denny, 1982 (basis of record)
Achnantheiopsis oestrupii (Cleve-Euler) Lange-Bert., 1997 accepted as Planothidium oestrupii (A.Cleve) Round & L.Bukhtiyarova, 1996 (basis of record)
Achnantheiopsis peragalloi (Brun & Hérib.) Lange-Bert., 1997 accepted as Planothidium peragalloi (J.Brun & Héribaud-Joseph) Round & L.Bukhtiyarova, 1996 (basis of record)
Achnantheiopsis pericava (J.R.Carter) Lange-Bert., 1997 accepted as Planothidium pericavum (J.R.Carter) Lange-Bertalot, 1999 accepted as Achnanthes pericava J.R.Carter, 1966 (basis of record)
Achnantheiopsis pseudotanensis (Cleve-Euler) Lange-Bert., 1997 accepted as Planothidium pseudotanense (Cleve-Euler) Lange-Bertalot, 1999 accepted as Achnanthes pseudotanensis A.Cleve-Euler, 1953 (basis of record)
Achnantheiopsis pungens (Cleve-Euler) Lange-Bert., 1997 accepted as Planothidium pungens (Cleve-Euler) Lange-Bertalot, 1999 accepted as Achnanthes elliptica var. pungens Cleve-Euler, 1934 accepted as Skabitschewskia pungens (Cleve-Euler) Kulikovskiy & Lange-Bertalot, 2015 (basis of record)
Achnantheiopsis robusta (Hustedt) Lange-Bert., 1997 accepted as Planothidium robustum (Hustedt) Lange-Bertalot, 1999 (basis of record)
Achnantheiopsis robustior Lange-Bertalot, 1997 accepted as Planothidium robustius Lange-Bertalot, 1999 (basis of record)
Achnantheiopsis rostrata (Østrup) Lange-Bert., 1997 accepted as Planothidium rostratum (Østrup) Lange-Bertalot, 1999 (basis of record)
Achnantheiopsis salvadoriana (Hustedt) Lange-Bert., 1997 accepted as Planothidium salvadorianum (Hustedt) Lange-Bertalot, 1999 (basis of record)
Achnantheiopsis septentrionalis (Østrup) Lange-Bert., 1997 accepted as  (basis of record)
Achnanthepyla Perag., 1921 (basis of record)
Achnanthepyla arctica (Cleve) Perag., 1921 accepted as Achnanthes brevipes var. arctica (P. T. Cleve) T. Ko-Bayashi, 1965 accepted as Achnanthidium arcticum Cleve, 1873 (basis of record)
Achnanthepyla arctica var. incurvata (Østrup) 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 bongrainii var. dilatata Perag., 1924 (basis of record)
Achnanthepyla bongrainii var. parallela Perag., 1921 accepted as Achnanthes bongrainii var. parallela (Peragallo) Frenguelli & Orlando, 1958 (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 groenlandica (Cleve) Perag., 1921 accepted as Achnanthes groenlandica (Cleve) Grunow, 1880 (basis of record)
Achnanthepyla jamalinensis (Grunow in Cleve & Grunow) Perag., 1921 accepted as Achnanthes jamalinensis Grunow in Cleve & Grunow, 1880 (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)
Achnanthepyla temperei (Perag.) Perag., 1921 accepted as Achnanthes temperei M.Peragallo, 1908 (basis of record)
Achnanthes Bory, 1822 (additional source)
Achnanthes aapajärvensis Cleve-Euler, 1934 accepted as Achnanthes aapajaervensis A.Cleve, 1934 (basis of record)
Achnanthes abundans Manguin in Bourrelly & Manguin, 1954 accepted as Psammothidium abundans (Manguin, Bourrelly & Manguin) L.Bukhtiyarova, 1996 (additional source)
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 (basis of record)
Achnanthes abundans var. elliptica Manguin in Bourrelly & Manguin, 1955 accepted as Psammothidium abundans var. ellipticum (Manguin) R. Flower, 2005 (basis of record)
Achnanthes acares M.H.Hohn & Hellerman, 1963 (basis of record)
Achnanthes acidoclinata Lange-Bert., 1996 accepted as Psammothidium acidoclinatum (Lange-Bertalot) Lange-Bertalot, 1999 (basis of record)
Achnanthes acus Simonsen ex F.Hinz et al., 2012 (basis of record)
Achnanthes acuta Frenguelli, 1953 (basis of record)
Achnanthes adamantiformis (R.E.M.Archibald) R.E.M.Archibald, 1971 accepted as Navigiolum adamantiforme (Archibald) Taylor & Lange-Bertalot (basis of record)
Achnanthes adamsii Cholnoky, 1964 (basis of record)
Achnanthes adnata Bory, 1822 (basis of record)

 Additional information

 for Actinoptychus undulatus f. sexappendiculata Grunow in Van Heurck, 1883

Originally published as Actinoptychus undulatus var. microsticta f. sexappendiculata Grunow in VanHeurck, 1883, ... [details]

 Additional information

 for Anomoeoneis brachysira var. thermalis (Grunow) Cleve-Euler, 1953

Cleve-Euler invalidly published a new combination "Anomoeoneis brachysira "beta" thermalis, not clearly indicating ... [details]

 Additional information

 for Anomoeoneis serians var. brachysira f. thermalis A.Cleve

Cleve-Euler invalidly published a new combination "Anomoeoneis brachysira "beta" thermalis, not clearly indicating ... [details]

 Nomenclature

 for Hemiaulus C.G. Ehrenberg, 1844

Name rejected vs. Hemiaulus Heiberg 1863 (see ICBN 1988, p. 120, ref. 006921). Two Hemiaulus species are listed in ... [details]