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Gamophyceae: Zygnematales: Desmidiaceae

Cosmarium contractum
Kirchner var. contractum

Cosmarium contractum Species [var. contractum]: Cell body 28-41 μm long, 18-31 μm wide, isthmus 5.3-8.7 μm wide, L/W=1.5; semicells broad ellipsoid, laterally circular; cellwall smooth or finely dotted, a single pyrenoid in each semicell.
[var. ellipsoideum (Elfving) W. et G.S. West]: Cell body 31-51 μm long, 24-42 μm wide, isthmus 7-12.5 μm wide, L/W=1.3; apex of semicells slightly flattened; cellwall smooth.
[f. jacobsenii (Roy) W. et G.S. West]: Semicells exactly ellipsoid, 28-47.6 μm long, 18-36.4 μm wide, isthmus 4.5-11.3 μm wide.
[var. minutum (Delponte) W. et G.S. West]: Cell body 19-28 μm long, 14-22 μm wide, isthmus 4.3-5.6 μm wide; semicells elongated ellipsoid, laterally circular, cellwall dotted.
(Illustrations of The Japanese Fresh-water Algae, 1977).
Similar species -- >> C. depressum; C. bioculatum; C. moniliforme;


Cosmarium contractum, stock Kashibaru-1, axenic culture (from May 10 to May 17), cell body 44 μm long, 31 μm wide, L/W=1.4, isthmus 10 μm wide, x 640, No.1, Kashibaru marsh, Karatsu city, Saga Pref., Japan, November 2006 by Y. Tsukii
scale 31 μm scale 63 μm scale 94 μm; x 640
Cosmarium contractum Cosmarium contractum Cosmarium contractum
Cell body (left) 43 μm long, 32 μm wide, L/W=1.3, isthmus 10 μm wide, x 640
Cosmarium contractum Cosmarium contractum
Cell body (bottom) 45 μm long, 30 μm wide, L/W=1.5, isthmus 10 μm wide, x 640
Cosmarium contractum Cosmarium contractum
Beginning of cell division
Cosmarium contractum Cosmarium contractum Cosmarium contractum
After cell division:
Cosmarium contractum Cosmarium contractum Cosmarium contractum Cosmarium contractum
Cosmarium contractum Cosmarium contractum
After cell division: Separating daughter cells
Cosmarium contractum Cosmarium contractum Cosmarium contractum Cosmarium contractum

Cosmarium contractum Kirchner var. contractum, axenic culture (from December 19, 2007 to February 1, 2008), cell body μm long, μm wide, L/W=, x 640, No.1, Kashibaru marsh, Karatsu city, Saga Pref., Japan, November 2006 by Y. Tsukii
scale 31 μm scale 63 μm scale 94 μm; x 640
Cosmarium contractum Cosmarium contractum Cosmarium contractum Cosmarium contractum Cosmarium contractum Cosmarium contractum Cosmarium contractum Cosmarium contractum Cosmarium contractum

Images of collecting locality: No.1, Kashibaru marsh, Karatsu city, Saga Pref., Japan, November 22, 2006 by Y. Tsukii


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