Genus: Mucous sheath, nearly invisible; heterocysts at base never become a large akinete (Illustrations of The Japanese Fresh-water Algae, 1977). Species: Trichome without mucilagenous seath, 4-6 μm wide, terminal cells rounded; cell-body length nearly equal to its width; heterocysts nearly spherical or ovoid, 6-8 μm in diam.; akinete cylindrical, 20-40 μm long, 8-10 μm wide, present at both side of akinete (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640