Species: Cell body large, elongated, slightly curved, both side nearly straight at central region, 300-(448-672)-768 μm long, 13-(20-48) μm wide, L/W=14-16; cell wall brownish, finely striated (about 12 lines within 10 μm); 9-11 pyrenoids in each semicells (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: Futayo-no-ike (pond) near Haguro mountain, Haguro town, Yamagata Pref., Japan, August 3, 2006 by Y. Tsukii