Division Bacillariophyta Engl. & Gilg (1919) see Phylum Bacillariophyta Engl. & Gilg (1919) Class Coscinodiscophyceae Round & R.M. Crawford (1990) - radial centrics Subclass Cymatosirophycidae Round & R.M. Crawford (1990) see Class Mediophyceae Medlin & Kaczmarska (2004) Order Cymatosirales Round & R.M. Crawford (1990) Family Rutilariaceae De Toni (1894) Genus Syndetocystis Ralfs ex Grev. (1866)