Subgenus: Eucosmarium
Genus: Unicellular; variable in shape; a constriction at the center of the cell body; mostly longer than wide; flattened; each semicell hemispherical, spherical, ellipsoidal, rectangular, pyramidal or kidney-shaped; no apical indentation.
Subgenus: Cell body dorso-ventrally compressed, with strong constriction at the center, transverse section elliptical or diamond-shaped (Illustrations of The Japanese Fresh-water Algae, 1977).
| Section Ornatae: Semicells circular, elliptical, reniform; cell surface granulated or spiny | ||||
C. granulatum 2 samples 130 x 90 μm 2004-2008 |
C. logiense v. logiense 13 samples 50-82 μm 1998-2008 |
C. logiense f. expansa 13 samples 50-82 μm 1998-2008 |
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C. reniforme var. reniforme 5 samples 43-53 μm 2001-2005 |
C. reniforme var. compressum 2 samples 53-72 x 48-60 μm 2001-2005 |
C. reniforme var. elevatum 4 samples 52,56 x 36 μm 2004-2008 |
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C. perincisum 55 x 45 μm 56 x 44 μm near Ayu-kawa b. Fujioka Gunma, 2004 |
C. perincisum μm Kannon-numa 11 Shimogo Fukushima, 2008  |
C. perincisum 39 x 34 μm, right Kurihashi Saitama, 2001 |
C. perincisum 57 x 37 μm, right Imou bog Toyohashi Aichi, 2006 |
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C. portianum v. portianum 10 samples 2003-2008 |
C. portianum v. nephroideum 2 sample 2003-2008 |
C. portianum f. major 3 samples 2000-2004 |
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C. ornatum 12 samples 18-38 μm 1999-2008 |
Cosmarium sp. C. depressum ? 20 x 22 μm Uruguay, 1999 |
Cosmarium sp. C. depressum ? 23 x 23 μm water reservoir near Yamaguchi Univ. Yamaguchi, 2004 |
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