Kingdom Protoctista Hogg, 1860
   Phylum Bacillariophyta Engl. & Gilg (1919) - diatoms see [unranked] Diatomea Kütz. (1844)
     1 Class Coscinodiscophyceae Round & R.M. Crawford (1990) - radial centrics
     1.0 Class Coscinopiscophyceae see Class Coscinodiscophyceae Round & R.M. Crawford (1990)
     2 Class Fragilariophyceae Round (1990) - araphid, pennate diatoms see Class Bacillariophyceae Haeckel (1878)
     3 Class Bacillariophyceae Haeckel (1878) - pennates