Image © Marien van Westen

Staurodesmus dickiei. Notice 3-radiate semicells with convergent spines.

Cell dimensions (L x B, exclusive of spines): 34 x 37 µm

 

 

Desmid of the month
November 2015

Staurodesmus dickiei

Staurodesmus dickiei should be compared with Std. mucronatus. Both species are characterized by 3-(4-)radiate semicells, in frontal view showing an elliptic outline (at least when focusing on their nominate varieties). The main discriminating feature between Std. dickiei and Std. mucronatus is the direction of the spines: convergent in Std. dickiei, divergent to parallel in Std. mucronatus. Zygospores in Std. dickiei, like in most Staurodesmus species, are globose and furnished with simple spines. In the Netherlands, Std. dickiei is of occasional occurrence in oligo-mesotrophic moorland pools. Zygospores are but incidentally encountered.

Image © Marien van Westen

Another cell of Std. dickiei in frontal view showing elliptic semicells characteristic of the nominate variety.

 

 

 


Image © Marien van Westen

Cell of Std. dickiei in apical view showing 3-radiate configuration.


Image © Marien van Westen

Std. dickiei var. circularis, differing from the nominate variety by a semicircular outline of the semicell.

Image © Koos Meesters   

Zygospore of Std. dickiei.