Division Bacillariophyta Engl. & Gilg (1919) see Phylum Bacillariophyta Engl. & Gilg (1919) Class Coscinodiscophyceae Round & R.M. Crawford (1990) - radial centrics Subclass Biddulphiophycidae Round & R.M. Crawford (1990) see Class Mediophyceae Medlin & Kaczmarska (2004) Order Biddulphiales Willi Krieg. (1954) Family Biddulphiaceae Kütz. (1844) Genus Terpsinoë Ehrenb. (1843) see Genus Terpsinoe Ehrenb. (1843)