Desmid of the month
January 2009

Staurodesmus cuspidatus

Std. cuspidatus is a triradiate Staurodesmus species characterized by a highly elongate isthmus. The semicell body (above the isthmus) is about triangular in outline. Length and projection of the spines are rather variable. The globose zygospores are furnished with long spines arising from a conical base. In the Netherlands Std. cuspidatus is a fairly common species in mesotrophic, slightly acidic fen hollows and moorland pools where it incidentally even may cause a bloom. Zygospores, on the contrary, have been found only a few times.

Cell of Std. cuspidatus in both frontal view (only partly in focus) and apical view (mouse over). Notice the elongate isthmus.

Cell dimensions (L x B, spines excluded): ca 30 x 25 µm

Zygospore of Std. cuspidatus

Another form of Std. cuspidatus marked by curved, somewhat converging spines.



A bloom of Std. cuspidatus