Division Bacillariophyta Engl. & Gilg (1919) see Phylum Bacillariophyta Engl. & Gilg (1919) Class Fragilariophyceae Round (1990) - araphid, pennate diatoms see Class Bacillariophyceae Haeckel (1878) Subclass Fragilariophycidae Round (1990) - core araphid diatoms Order Rhabdonematales Round & R.M. Crawford (1990) Family Rhabdonemataceae Round & R.M. Crawford (1990) Genus Rhabdonema Kütz. (1844)