Species: Cell body cylindrical or ellipsoidal, tapered to both ends, 35-79 μm long,
(16-21)-36 μm wide; both ends broadly rounded; cell wall thin, brownish in color,
finely lined (15-18/10 μ)
(Illustrations of The Japanese Fresh-water Algae, 1977).
Penium polymorphum Perty,
cell body 63 μm long, 23 μm wide, L/W=2.7,
x 640, Shibu-ike (pond), Shiga highland, Yamanouchi town, Nagano Pref., Japan, June 19, 2005 by Y. Tsukii
31 μm
63 μm
94 μm; x 640