Kingdom Protoctista Hogg, 1860
   Phylum Bacillariophyta Engl. & Gilg (1919) - diatoms see [unranked] Diatomea Kütz. (1844)
     Class Bacillariophyceae Haeckel (1878) - pennates
       Subclass Bacillariophycidae D.G.Mann (1990) - raphid diatoms
         Order Bacillariales Hendey (1937)
           Family Bacillariaceae Ehrenb. (1831)
             1 Genus Nitzschia Hassall (1845)
             2 Genus Hantzschia Grunow (1877)
             3 Genus Denticula Kütz. (1844)
             4 Genus Gomphonitzschia Grunow (1868)
             5 Genus Cymbellonitzschia Hust. (1924)
             6 Genus Simonsenia Lange-Bert. (1979)
             7 Genus Gomphotheca Hendey & P.A. Sims (1982)
             8 Genus Tryblionella W.Sm. (1853)
             9 Genus Psammodichyon see Genus Psammodictyon D.G.Mann (1990)