Species [var. lunula] : Cell body large,
250-(430-552)-1000 μm long, 47-(73-89)-120 μm wide,
L/W=5-8; inner-side nearly straight, outer-side convex;
tapered at both termini (broad circle, slightly inversed); cell wall smooth, transparent, without bands;
chloroplasts with many pyrenoids.
[var. biconvexum Schmidle]: Inner-side also convex;
455-603 μm long, 85-126 μm wide,
(Illustrations of The Japanese Fresh-water Algae, 1977).