Division Bacillariophyta Engl. & Gilg (1919) see Phylum Bacillariophyta Engl. & Gilg (1919)
   Class Bacillariophyceae Haeckel (1878) - pennates
     Subclass Bacillariophycidae D.G.Mann (1990) - raphid diatoms
       Order Thalassiophysales D.G.Mann (1990)
         Family Catenulaceae Mereschk. (1902)
           Genus Undatella Paddock & P.A. Sims (1980)