Species [var. senarium ]: Cell body 21-31 μm long (excluding projections), 29-36 μm long (including projections), 27-34 μm wide (including projections), isthmus 8.4-12 μm wide.
[ var. simplex Hirano ]: Smaller than var. senarium, 23 μm (excluding projections), 44 μm (including projections), 43 μm wide (including projections), isthmus 7 μm wide; projections at side margins of semicells are simple spines (not dichotomous).
[ var. nigrae-silvae Schmidle ]: 2 ring of dented structures surrounding each corner, 29 μm (including projections), 36.4 μm wide, isthmus 12.5 μm wide (Illustrations of The Japanese Fresh-water Algae, 1977)