Division Bacillariophyta Engl. & Gilg (1919) see Phylum Bacillariophyta Engl. & Gilg (1919)
   Class Coscinodiscophyceae Round & R.M. Crawford (1990) - radial centrics
     Subclass Lithodesmiophycidae Round & R.M. Crawford (1990) see Class Mediophyceae Medlin & Kaczmarska (2004)
       Order Lithodesmiales Round & R.M. Crawford (1990)
         Family Lithodesmiaceae Round (1990)
           Genus Ditylum L.W. Bailey (1861)