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Gamophyceae: Zygnematales: Desmidiaceae

Cosmarium laeve
var. octangularis (Wille) W. et G.S. West

Cosmarium laeve 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 (Illustrations of The Japanese Fresh-water Algae, 1977).
Species: Cell body 15-(18-32)-34 μm long, 11.5-(12.6-22.4)-23 μm wide, L/W=1.5, isthmus 2.8-8 μm wide, semicells half-ellipsoidal or rounded pyramidal, apices slightly depressed, cell wall with a small number of dots; a single chloroplast with a pyrenoid in each semicell (Illustrations of The Japanese Fresh-water Algae, 1977).
Similar species -- >> C. granatum;


Cosmarium laeve var. octangularis (Wille) W. et G.S. West (or C. impressulum ?), cell body 22 μm long, 15 μm wide, isthmus 5 μm wide, L/W=1.5, x 640, used waterfield near Karakemi marsh (Yasaka village), Matsuzaki, Omachi city, Nagano Pref., Japan, April 24, 2005 by Y. Tsukii
scale 31 μm scale 63 μm scale 94 μm; x 640
Cosmarium laeve


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