Species [ var. dianae ]: Cell body slightly curved, tapered toward both ends, truncated with slanted edges, small pores present at outside of both termini, inner side at center slightly convex, 150-380 μm long, 15-40 μm wide, L/W = 10-12; cell wall smooth; chloroplasts with 5-8 pyrenoids in each chloroplast (Illustrations of The Japanese Fresh-water Algae, 1977). Cell body 160-323 μm long, 20-28 μm wide, L/W=8.3-12; chloroplasts with about 6 laminae; semicells with 4-8 pyrenoids (Photomicrographs of the Freshwater Algae, vol. 6, 1987). [var. minus]: Cell body 140-150 μm long, 15 μm wide (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: a wetland near Ichinose-enchi (along super forest road), Norikura highland, Azumi, Matsumoto city (formerly Azumi village), Nagano Pref., Japan, June 8, 2006 by Y. Tsukii