Species:
Cell body cylindrical, medium in size, both ends broadly rounded,
(56-65)-80 μm long, 20-31 μm wide,
L/W=2-2.5; cell wall thick, densely dotted, transparent or brownish in color
(Illustrations of The Japanese Fresh-water Algae, 1977).
Penium rufescens Cleve,
cell body 70 μm long, 26 μm wide,
x 640, Omine-numa (pond/marsh), Tsukiyono town, Gunma Pref., Japan, September 2003 by Y. Tsukii
31 μm
63 μm
94 μm; x 640
Penium rufescens Cleve:
Vegetative cells cylindrical, L/W = 2-2.5,
(56-65) -80 μm long,
20- (24-25) -31 μm diam.,
cell wall thick, slightly constricted at middle
(Illustrations of The Japanese Fresh-water Algae, 1977).