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 Biddulphiophycidae Round & R.M. Crawford (1990) see Class Mediophyceae Medlin & Kaczmarska (2004) 1 Order Eupodiscales see Order Triceratiales Round & R.M. Crawford (1990) 2 Order Biddulphiales Willi Krieg. (1954) 3 Order Hemiaulales Round & R.M. Crawford (1990) 4 Order Anaulales Round & R.M. Crawford (1990)