Cell body flat, large, variable in shape, longer than wide; strong constriction at center;
each semicell with several notches; cell wall with many short spines
(Illustrations of The Japanese Fresh-water Algae, 1977).
Micrasterias americana Ehrenberg ex Ralfs var. americana,
cell body μm long, μm wide, L/W=, isthmus μm wide,
x 640, Ohnuma (a pond at Ohnuma enchi), Nasu-shiobara city (formerly Shiobara town), Tochigi Pref., Japan, August 2, 2008, collected by Eizaburo Tsukii, photo by Y. Tsukii
150 μm; x 400 :
94 μm; x 640