Species [ var. gracile ]: Cell body 28-47 μm long, 39-77 μm wide (including arms), isthmus 8.4-11 μm; [ var. coronulatum Boldt ]: Cell body 26-28 μm long, 34-41 μm wide (including arms), isthmus 6.5-10 μm; [ var. ornatum Krieger ]: Cell body 38.7 μm long, 62.4 μm wide (including arms), isthmus 13 μm; a pair of warts present at each posterior margin of semicells (Illustrations of The Japanese Fresh-water Algae, 1977)

31 μm 63 μm 94 μm; x 640

Images of collecting locality: Azami-ike (pond), Norikura highland, Azumi, Matsumoto city (formerly Azumi village), Nagano Pref., Japan, June 8, 2006 by Y. Tsukii