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Gamophyceae: Zygnematales: Desmidiaceae

Cosmarium quadrum
Lundell var. quadrum

Cosmarium quadrum 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 rectangular, 53-90 μm long, 47.6-85 μm wide; isthmus 19-30 μm wide; semicells subrectangular, with rounded corners; side view nearly circular; apical view elongated ellipsoidal; marginal granules 34-37 in number (Illustrations of the Japanese fresh-water algae, 1977).


Cosmarium quadrum Lundell var. quadrum, cell body 84 μm long, 68 μm wide, isthmus 25 μm wide, x 640, Kabuto-yama sizen-kansatsu ike (pond), Kabuto-yama, Nishi-no-miya city, Hyogo Pref., Japan, September 10, 2004 by Y. Tsukii
scale 31 μm scale 63 μm scale 94 μm; x 640
Cosmarium Cosmarium Cosmarium Cosmarium Cosmarium Cosmarium
Cell body 83 μm long, 65 μm wide, isthmus 23 μm wide, x 640
Cosmarium Cosmarium

Cosmarium margaritatum (Lundell) Roy et Bisset var. margaritatum: Cell body 78-90 μm long, 70-72 μm wide, L/W=1.20-1.25, isthmus 22-25 μm wide; semicells subrectangular, basal angles rounded, lateral margins convex, anical angles broadly rounded, apex truncate and flat; cell wall regularly granulated, between the granules finely punctated; side view of the semicells subcircular, vertical view oblong-elliptic; zygospores spherical or slightly depressed, with yellowish smooth wall, surrounded by mucilagenous sheath, 44.8-47.6 μm in diam. (Photomicrographs of the Freshwater Algae, vol. 3, 1985).

Cosmarium margaritatum f. minor (Boldt) Roy et Bisset: Cell body rectangular, 58-59 μm long, 54 μm wide; isthmus 18-19 μm wide (Illustrations of the Japanese fresh-water algae, 1977).

Cosmarium quadrum Lundell var. quadrum: Cell body rectangular, 53-90 μm long, 47.6-85 μm wide; isthmus 19-30 μm wide; semicells subrectangular, with rounded corners; side view nearly circular; apical view elongated ellipsoidal; marginal granules 34-37 in number (Illustrations of the Japanese fresh-water algae, 1977).

C. quadrum var. minus Nordstedt: Cell body 45-51 μm long, 40-47 μm wide, constriction 17-19 μm wide (Illustrations of The Japanese Fresh-water Algae, 1977).


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