Heterosigma

…50 species; includes Chattonella, Gonyostomum, Heterosigma, Psammamonas, and Vacuolaria. Class Synurophyceae Previously placed in Chrysophyceae; silica-scaled; unicellular or colonial flagellates sometimes alternating with capsoid benthic stage; cells covered with elaborately structured silica scales; approximately 250 species;