Staurastrum gracile Ralfs var gracile: Cell body 28-47 μm long (including arms), 39-77 μm wide (including arms), isthmus 8.4-11 μm wide; in apical view, small 4 knob-like structures at each side (Illustrations of The Japanese Fresh-water Algae, 1977)
Staurastrum gracile var. coronulatum Boldt: Cell body 26-28 μm long (including arms), 34-41 μm wide (including arms), isthmus 6.5-10 μm wide; in apical view, 2 knob-like structures at each side, each knob with a slight depression (Illustrations of The Japanese Fresh-water Algae, 1977)
Staurastrum gracile var. ornatum Krieger: Cell body 38.7 μm long (including arms), 62.4 μm wide (including arms), isthmus 13 μm wide; in apical view, a couple of knob-like structures at each side (Illustrations of The Japanese Fresh-water Algae, 1977)