Species: Cell body 24-40.5 μm long, 21-36.5 μm wide, isthmus 8.4-16 μm; semicells slightly twisted with each other; apical view triangular with each margin slightly convexed; side view elliptical diamond-shaped; cell wall covered with granules regularly arranged around each arm (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.3, Kashibaru marsh, Karatsu city, Saga Pref., Japan, November 22, 2006 by Y. Tsukii