Species [var. setaceum]: 
Cell body quickly attenuated toward both ends (cf. C. ralfsii), 
each extended part longer than spindle-shaped part at middle (cf. C. kuetzingii), 
150-(252-528)-600 μm long, 6-(8.6-17) μm wide, 
L/W=30-33; cell wall transparent or slightly yellowish, finely striated 
(Illustrations of The Japanese Fresh-water Algae, 1977). 
 | 
Closterium setaceum Ehrenberg (or C. kuetzingii Brébisson ?), 
cell body  μm long,  μm wide, L/W=, 
x 640, No.11, Kannon-numa Forest Park (pond), Shimogo town, Fukushima Pref., Japan, November 15, 2008, by Y. Tsukii
 50 μm
 100 μm
 150 μm; x 400 : 
 31 μm
 63 μm
 94 μm; x 640
Images of collecting locality: 
No.11, Kannon-numa Forest Park (pond/marsh), Shimogo town, Fukushima Pref., Japan, November 15, 2008, by Y. Tsukii