Genus: Unicells or a colony of spherical cells covered with a distinct sheath.
Species: Colonies consisting of many cells lacking definite layers; cells gathered at the center of the colonies; cell body (excluding sheath) larger than 6 μm in diameter (Illustrations of The Japanese Fresh-water Algae, 1977).
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var. distans: cell body 6.5-7 μm in diam. 
C. limneticus ?
7 μm
Iroha-numa
Zao mountain
Yamagata, 2005
C. limneticus ?
7 μm
Tanohara marsh
Shiga highland
Nagano, 2006
C. limneticus ?
7 x 6 μm
Sukawa highland
Kurikoma mt.
Akita, 2007
