Kingdom Protoctista Hogg, 1860
   Phylum Bacillariophyta Engl. & Gilg (1919) - diatoms see [unranked] Diatomea Kütz. (1844)
     Class Fragilariophyceae Round (1990) - araphid, pennate diatoms see Class Bacillariophyceae Haeckel (1878)
       Subclass Fragilariophycidae Round (1990) - core araphid diatoms
         Order Pseudohimantidiales see Order Protoraphidales Round (1990)
           Family Pseudohimantidiaceae see Family Protoraphidaceae Simonsen (1970)
             1 Genus Pseudohimantidium Hust. & Krasske (1941)
             2 Genus Protoraphis