Image © Alfred van Geest

Cell of Cosmarium portianum. Notice reniform semicells and elongate isthmus.
Cell dimensions (L x B): 38 x 31 µm

mouse over images © Alfred van Geest

Cell of C. portianum in lateral view.

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Desmid of the month
April 2014

Cosmarium portianum

C. portianum is a medium-sized granulate Cosmarium that may be readily identified by its reniform semicells and a distinctly elongate isthmus. Cell wall granules are arranged in regular transverse and longitudinal series. The globose zygospore is furnished with obtuse-conical protuberances. In the Netherlands, C. portianum is of occasional occurrence in mesotrophic fen hollows and moorland pools. Zygospores have only been encountered a few times.

Image © Alfred van Geest

Another cell of C. portianum showing regular arrangement of cell wall granules.

Image Hanny Kooijman née van Blokland © IBED

SEM picture of C. portianum. Notice regular longitudinal and transverse series of cell wall granules.

Cell of C. portianum in apical view displaying a broadly elliptic semicell outline.

Zygospore of C. portianum. Notice stout, obtuse-conical protuberances.

Desmid of the month April 2014

Cosmarium portianum

Desmid of the month
April 2014