Kingdom Protoctista Hogg, 1860
   Phylum Bacillariophyta Engl. & Gilg (1919) - diatoms see [unranked] Diatomea Kütz. (1844)
     Class Coscinodiscophyceae Round & R.M. Crawford (1990) - radial centrics
       Subclass Coscinodiscophycidae Round & R.M. Crawford (1990)
         Order Melosirales R.M. Crawford (1990)
           Family Stephanopyxidaceae Nikolaev (1984)
             Genus Stephanopyxis (Ehrenb.) Ehrenb. (1845)