Desmid of the month
March 2005

Closterium costatum

Most Closterium species are characterized by arched cells. A relevant diagnostic feature in species identification is found in the appearance of a possible cell wall sculpturing. The cell wall of Closterium costatum is distinctly striate. Whereas in most striate Closterium species striation is fine and close, in Closterium costatum the striae are mutually far apart and rib-like (costate).

In the Netherlands Closterium costatum is of occasional occurrence in slightly acidic, mesotrophic fen hollows and moorland pools.

Living cell of Closterium costatum (because of the somewhat unusual, thick-set cell shape it might be assigned var. subcostatum, see Ruzicka’s 1971 flora).  Cell wall striation is well visible, particularly in close-up (mouse-over).

Cell dimensions (L x B): ca 300 x 50 µm


Image on the left:

Dead, empty cell of Closterium costatum showing striation of cell wall even better (cell wall brownish coloured by impregnation of iron compunds).

In close-up (mouse-over) between the costae also more delicate striae are to be observed