Cosmarium obtusatum (Schmidle) Schmidle 1898

    Cells large size, slightly longer than broad measures 45–55 μm in length and 38–46 μm in width. Cells deeply constricted at the center and sinus is linearly closed and wide at proximal side, isthmus is 8–12 μm. Semicell trapezoid shape and basal angle rounded; lateral margins convex with 7-8-undulations. Apex truncated or slightly swollen, cells with granules and cell wall clearly punctated. Semicells elliptical lateral view and round-oblong in vertical view.