Cosmarium turpiniiImage © Alfred van Geest

Cell of Cosmarium turpinii (var. podolicum). Notice trapeziform semicell outline and slightly concave lateral sides.

Cell dimensions (L x B): 67 x 60 µm

 

 

Desmid of the month
July 2012

Cosmarium turpinii

C. turpinii, belonging to the group of granulate Cosmaria, is marked by fairly large, trapeziform semicells with more or less concave lateral sides.  In var. podolicum (which is much more common than the nominate variety) the outline of the semicells at their lateral sides is slightly emarginate-crenate. The semicell centre is provided with two big tumours each of which is ornamented with some concentric series of granules. In the Netherlands, C. turpinii is of rather common occurrence in mesotrophic, slightly alkaline water bodies.

Cosmarium turpinii, mouse over, exhibiting the central tumours

mouse over images © Alfred van Geest

Cell of C. turpinii showing in each semicell the pair of central tumours furnished with concentric circles of granules.

Cosmarium turpinii, empty cellImage © Alfred van Geest

Empty cell of C. turpinii well exhibiting the pattern of cell wall granulation.

Cosmarium turpinii, SEM pictureImage © Jan Šťastný

SEM picture of Cosmarium turpinii (var. podolicum)