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 61 μm long, 25 μm wide, L/W=2.4,
x 640, Iroha-numa (marsh), Zao mountain, Yamagata city, Yamagata Pref., Japan, July 9, 2005 by Y. Tsukii
31 μm
63 μm
94 μm; x 640
Cell body 56 μm long, 25 μm wide, L/W=2.2, x 640