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 Protoraphidales Round (1990) see Order Protoraphidales Round ex Gogorev (2015) Family Protoraphidaceae Simonsen (1970) Genus Pseudohimantidium Hust. & Krasske (1941)