Species: Cell body 46-62 μm long, 36-45 μm wide, L/W= 1.25-1.33; semicells pyramidate-trapeziform, apex trucated and 4-6 crenate, lateral margins convex, 6-8 crenate, all the crenations consist of bigranules or emarginations, bicrenate granules arranged radially from the center, which locates just above the isthmus; the 6-7 vertical series of granulte ridges present at the center; side view of the semicells ovate-oblong, convexing at the center for both side; vertical view elliptic-oblong (Photomicrographs of the Freshwater Algae, vol. 3, 1985).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.2, Lake Nakatsuna, Omachi city, Nagano Pref., Japan, June 4, 2007 by Y. Tsukii