Desmid of the month
May 2011

Cosmarium brebissonii

C. brebissonii is a large-sized, firm-lined Cosmarium species with a granulate cell wall. Semicells are about trapeziform with very broadly rounded angles. Compared with many other species meeting those features C. brebissonii is to be recognized by its remarkably stout, conical granules that are rather evenly distributed over the cell wall (not being arranged in a particular pattern). C. brebissonii is characteristic of acidic, oligo-mesotrophic bog sites. In the Netherlands it is very rare.

 

Cosmarium brebissoniiImage © Alfred van Geest

 

Cosmarium brebissonii
mouse-over image © Ton (A.M.T.J.) Joosten

Cosmarium brebissonii. Notice the large dimensions and the stout, conical granules that are rather evenly distributed over the cell wall.

Cell dimensions (L x B): 95 x 75 µm

 

 

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Another cell of C. brebissonii, collected in the Czech Republic

 

SEM picture of Cosmarium brebissonii
Image © Jan Šťastnýl
SEM picture of Cosmarium brebissonii