Acanthoceras H. Honigmann, 1909 (habitat flag source)
Achnanthales accepted as Mastogloiales (basis of record)
Actinella F.W. Lewis, 1864 (habitat flag source)
Actinocyclus Ehrenberg, 1837 (habitat flag source)
Actinoptychus Ehrenberg, 1843 (habitat flag source)
Adoneis G.W. Andrews & P. Rivera, 1987 (habitat flag source)
Amphipleuraceae Grunow, 1862 (habitat flag source)
Amphitetras Ehrenberg, 1840 (habitat flag source)
Anaulaceae (Schütt) Lemmermann, 1899 (habitat flag source)
Anaulales (basis of record)
Anaulales (original description)
Anaulus Ehrenberg, 1844 (habitat flag source)
Aneumastus D.G. Mann & A.J. Stickle in F.E. Round, R.M. Crawford & D.G. Mann, 1990 (habitat flag source)
Anomoeoneidaceae D.G. Mann, 1990 (habitat flag source)
Anomoeoneis E. Pfitzer, 1871 (habitat flag source)
Arachnoidiscaceae accepted as Stictodiscaceae (habitat flag source)
Arachnoidiscales accepted as Stictodiscales (basis of record)
Arachnoidiscales accepted as Stictodiscales (original description)
Arachnoidiscus H. Deane ex G. Shadbolt, 1852 (habitat flag source)
Arcocellulus G.R. Hasle, H.A. von Stosch & E.E. Syvertsen, 1983 (habitat flag source)
Ardissonea De Notaris, 1870 (habitat flag source)
Ardissoneaceae Round (habitat flag source)
Ardissoneales accepted as Toxariales (original description)
Ardissoneales accepted as Toxariales (basis of record)
Asterionella Hassall, 1850 (habitat flag source)
Asterionellopsis F.E. Round in F.E. Round, R.M. Crawford & D.G. Mann, 1990 (habitat flag source)
Asterolampra Ehrenberg, 1844 (habitat flag source)
Asterolampraceae Smith, 1872 (habitat flag source)
Asterolamprales (basis of record)
Asterolamprales (original description)
Asteromphalus Ehrenberg, 1844 (habitat flag source)
Attheya T. West, 1860 (habitat flag source)
Attheyaceae Round & R. M. Crawford (habitat flag source)
Aulacodiscaceae (Schütt) Lemmermann, 1903 (habitat flag source)
Aulacodiscus C.G. Ehrenberg, 1844 (habitat flag source)
Aulacoseiraceae Crawford (habitat flag source)
Aulacoseirales (original description)
Aulacoseirales (basis of record)
Auliscus Ehrenberg, 1843 (habitat flag source)
Auriculaceae Hendey (habitat flag source)
Azpeitia M. Peragallo in Tempère & H. Peragallo, 1912 (habitat flag source)
Bacillariaceae Ehrenberg, 1831 (habitat flag source)
Bacillariales (basis of record)
Bacillariophyta (extant flag source)
Bacillariophyta (habitat flag source)
Bacillariophyta (basis of record)
Bacteriastrum Shadbolt, 1854 (habitat flag source)
Bellerochea Van Heurck, 1885 (habitat flag source)
Bellerocheaceae Crawford, 1990 (habitat flag source)
Berkeleyaceae Mann (habitat flag source)
Biddulphia S.F. Gray, 1821 (habitat flag source)
Biddulphiaceae Kützing, 1844 (habitat flag source)
Biddulphiales (basis of record)
Biddulphiopsis H.A. von Stosch & R. Simonsen, 1984 (habitat flag source)
Bleakeleya F.E. Round in F.E. Round, R.M. Crawford & D.G. Mann, 1990 (habitat flag source)
Brachysiraceae Mann, 1990 (habitat flag source)
Brockmanniella Hasle, Stosch & Syvertsen, 1983 (habitat flag source)
Campylosira Grunow ex Van Heurck, 1885 (habitat flag source)
Catacombas D.M. Williams & F.E. Round, 1986 accepted as Synedra Ehrenberg, 1830 (habitat flag source)
Catenulaceae Mereschkowsky, 1902 (habitat flag source)
Cavinulaceae D.G. Mann (habitat flag source)
Centronella M. Voigt, 1902 (habitat flag source)
Cerataulina H. Peragallo ex F. Schütt in Engler & Prantl, 1896 (habitat flag source)
Cerataulus Ehrenberg, 1844 (habitat flag source)
Chaetoceraceae Smith, 1872 accepted as Chaetocerotaceae Ralfs, 1861 (habitat flag source)
Chaetoceros Ehrenberg, 1844 (habitat flag source)
Chaetocerotales (original description)
Chaetocerotales (basis of record)
Chrysanthemodiscaceae (habitat flag source)
Chrysanthemodiscales accepted as Stictodiscales (original description)
Chrysanthemodiscales accepted as Stictodiscales (basis of record)
Chrysanthemodiscus A. Mann, 1925 (habitat flag source)
Climacodium Grunow, 1868 (habitat flag source)
Climacosphenia Ehrenberg, 1841 (habitat flag source)
Climacospheniaceae (habitat flag source)
Climacospheniales accepted as Toxariales (original description)
Climacospheniales accepted as Toxariales (basis of record)
Cocconeidaceae Kützing, 1844 (habitat flag source)
Cometes H. Edsbagge, 1966 (name verified source)
Cometes H. Edsbagge, 1966 (basis of record)
Corethraceae Lebour, 1930 (habitat flag source)
Corethrales (original description)
Corethrales (basis of record)
Corethron Castracane, 1886 (habitat flag source)
Coscinodiscaceae Kützing, 1844 (habitat flag source)
Coscinodiscales (original description)
Coscinodiscales (basis of record)
Coscinodiscus Ehrenberg, 1839 (habitat flag source)
Cosmioneidaceae D. G. Mann (habitat flag source)
Craspedodiscus Ehrenberg, 1844 † (habitat flag source)
Ctenophora (Grunow) D.M. Williams & F.E. Round, 1986 (habitat flag source)
Cyclophora Castracane, 1878 (habitat flag source)
Cyclophoraceae (habitat flag source)
Cyclophorales (original description)
Cyclophorales (basis of record)
Cyclostephanos Round ex Theriot, Hakansson, Kociolek, Round & Stoermer, 1987 (habitat flag source)
Cymatosira Grunow, 1862 (habitat flag source)
Cymatosiraceae Hasle, von Stosch & Syvertsen, 1983 (habitat flag source)
Cymatosirales (basis of record)
Cymatosirales (original description)

 Taxonomic remark

 for Centrales

Former single order for all centric diatoms, not used since the more extensive treatment of Round et al., 1990, ... [details]

 Taxonomic remark

 for Druridgia Donkin, 1861

Misspelled Druridgea in many publications, however Druridgia is correct, refer original work and Round et al., 2000. [details]

 Taxonomic remark

 for Pennales

Former single order for all pennate diatoms, not used since the more extensive treatment of Round et al., 1990, ... [details]