Cosmarium humile var. substriatum (Nordstedt) Schmidle 1895

    Cell small, 1.1-1.2 longer than broad, constricted deeply at median, sinus linear and closed. Cells 15-20 μm long, 14-17 μm broad and isthmus 4-5 μm. Semicell rectangular in shape, and the end of apex and center of lateral margins retuse. The granules arranged in 2 rows under margins. Semicell circular in lateral view and elliptical in vertical view.