Species [ var. abbreviatum ]: Cell body (11-15)-22 μm long, (11-14.5)-22
μm wide, L/W=1.0, isthmus (4.2-5.6)-7 μm wide; semicells broad
hexagon in shape.
[ f. minor ]: 8-8.4 μ;m long, 8.5-9 μm wide.
[ var. planctonicum ]: (14)-19-29 μm long, (14)-22-30 μm wide;
each corner rounded, apical margin convex.
[ f. pygmaea ]: Cell body smaller, upper side of lateral margins longer than lower side and concave,
11-14 μm long, 12-14 μm wide, isthmus 4.2-6 μm wide.
[ var. gremanicum ]: Apical and lateral margins slightly concave, 12.6 μm long,
11.2 μm wide, isthmus 3.4 μm wide
(Illustrations of The Japanese Fresh-water Algae, 1977).
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