Species: Cell body small, (20-22)-42 μm long, (10.5-11)-17 μm wide, L/W=2-2.5; slightly depressed at the center; semicells gradually attenuated toward apex, lateral margins nearly straight, apex flat with rounded corners; cell wall smooth (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: No. 4, Mida-ga-hara (bog/marsh), Gassan (mountain), Tsuruoka city (formerly Haguro town) & Shonai town (formerly Tachikawa town), Yamagata Pref., Japan, August 3, 2006 by Y. Tsukii