Division Bacillariophyta Engl. & Gilg (1919) see Phylum Bacillariophyta Engl. & Gilg (1919) Class Coscinodiscophyceae Round & R.M. Crawford (1990) - radial centrics Subclass Thalassiosirophycidae Round & R.M. Crawford (1990) see Class Mediophyceae Medlin & Kaczmarska (2004) Order Thalassiosirales Glezer & I.V. Makarova (1986) Family Thalassiosiraceae M. Lebour (1930), nom. cons. Genus Bacteriosira Gran (1900)