Desmid of the month
November 2008

Cosmarium reniforme

As its name already indicates, Cosmarium reniforme is characterized by kidney-shaped semicells. The cell wall is beset with coarse granules, arranged in regular, longitudinal rows. Remarkably, contrary to the vegetative cells, zygospores of C. reniforme are perfectly smooth-walled.  C. reniforme is a common species with a wide ecological range occurring in both mesotrophic, acidic and eutrophic, alkaline water bodies. It may even be encountered in slightly brackish water. Zygospores, however, are rare.

Cosmarium reniforme, marked by kidney-shaped semicells and coarse granulation.

Cell dimensions (L x B): ca 60 x 50 µm

SEM picture of C. reniforme. Notice that the granules are arranged in longitudinal rows (and in obliquely decussate rows as well).

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Detail of cell wall showing that each granule is surrounded by a hexagon of pores



Zygospore of C. reniforme.