Staurodesmus triangularis. Notice triangular shape of semicell body, slightly elongate isthmus and long apical spines.

Cell dimensions (L x B): 18 x 36 µm



Desmid of the month
September 2020

Staurodesmus triangularis

 Staurodesmus triangularis is characterized by biradiate cells with a deep, widely open sinus and triangular semicells. Apical angles are furnished with long, about parallel spines. Often, the isthmus is somewhat elongate and semicell apices slightly elevated. In the Netherlands, Std. triangularis is of incidental occurrence in oligo-mesotrophic moorland pools, var. brevispina, characterized by shorter spines, being less rare than the nominate variety.

Image © Alfred van Geest

Staurodesmus triangularis var. brevispina. Notice relatively short spines and 'elevated' apices.

Image © Alfred van Geest

Cell of Staurodesmus triangularis var. brevispina in apical view showing its biradiate nature.