Species: Cell body deeply constricted, 32-40 μm long, 35-41 μm wide, constriction (isthmus) 11-13 μm wide, semicells reniform, apex slightly elevated and truncate, lateral margins convex and convergent upward, apex, lateral margins and the center of the semicells furnished with granules, other parts of cell walls smooth (Photomicrographs of the Freshwater Algae, vol. 3, 1985).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.9, Kannon-numa Forest Park (pond), Shimogo town, Fukushima Pref., Japan, November 15, 2008, by Y. Tsukii