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Gamophyceae: Zygnematales: Desmidiaceae or Closteriaceae

 Closterium acerosum
(Schrank) Ehrenberg ex Ralfs 1848

Closterium acerosum Species: 250-(396-576)-790 μm long, 25-(33-84) μm wide; cell body large, slightly curved; both termini tapered; pyrenoids 7-15 in each semicell (Illustrations of The Japanese Fresh-water Algae, 1977). Cell body slightly curved, gradually attenuated toward the truncated ends, which somewhat recurved due to the covexity of the inner margin near the ends; inner margin straight or slightly concave, outer margin convex, 300-500 μm long, 32-50 μm wide, L/W=9-14; cell wall smooth and colorless or sometimes delicately striated and yellowish-brown in color; chloroplasts with ridges containing 7-11 pyrenoids in central row (Photomicrographs of the Freshwater Algae, vol. 1, 1984).

Closterium acerosum (Schrank) Ehrenberg ex Ralfs, cell body 500 μm long, 47 μm wide, L/W=10.6, cell wall finely striated (?), x 200, x 400, x 640, Ko-sumida river near Sakae-bashi (Sakae bridge), Kasukabe city, Saitama Pref., Japan, February 12, 2006 by Y. Tsukii
scale 50 μm scale 100 μm scale 150 μm; x 400 : scale 31 μm scale 63 μm scale 94 μm; x 640
Closterium acerosum Closterium acerosum
Closterium acerosum Closterium acerosum Closterium acerosum Closterium acerosum
Cell body 380 μm long, 45 μm wide, L/W=8.4, x 200, x 400, x 640
Closterium acerosum Closterium acerosum
Closterium acerosum Closterium acerosum Closterium acerosum Closterium acerosum

Images of collecting locality: Ko-sumida river near Sakae-bashi (Sakae bridge), Kasukabe city, Saitama Pref., Japan, February 12, 2006 by Y. Tsukii

* C. acerosum (Schrank) Ehrenberg var. acerosum: 250-(396-576)-790 μm long, 25-(33-84) μm wide; cell body large, slightly curved; both termini tapered; pyrenoids 7-15 in each semicell (Illustrations of The Japanese Fresh-water Algae, 1977).

C. acerosum var. elongatum Brébisson: 650-(773-780)-915 μm long, (30-38)-40 μm wide; L/W = 15-33 (Illustrations of The Japanese Fresh-water Algae, 1977).

C. acerosum var. minus Hantzsch: 200-300 μm long, 18-25 μm wide; L/W = 7-11 (Illustrations of The Japanese Fresh-water Algae, 1977).

C. acerosum var. tumidum Borge: Slightly swell at center; 336-(384-494) μm long, 35-(42) μm wide; L/W = 8-12 (Illustrations of The Japanese Fresh-water Algae, 1977).

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