Cell of S. spongiosum in frontal view. Semicell lobes are furnished with concentric series of emarginate processes decreasing in size from apex to basis of the semicell lobe.

Cell dimensions (L x B): ca 60 x 50 µm



Desmid of the month
May 2008

Staurastrum spongiosum

S. spongiosum belongs to a group of Staurastra in which the cell wall is furnished with short, emarginate or furcate processes arranged in concentric circles around the semicell lobes. Semicells in S. spongiosum (when seen in frontal view) are about trapeziform in outline. In apical view they are triangular (rarely quadrangular) with about straight sides and rounded angles. In the Netherlands this characteristic, appealing species is of rather rare occurrence in slightly acidic, mesotrophic fen hollows and moorland pools.

Empty semicell of S. spongiosum in apical view
Image © Marien van Westen
(multifocus composition)

Empty semicell of S. spongiosum in apical view. Notice the series of emarginate cell wall processes decreasing in size from the semicell apex to each of the basal angles.

Cell of S. spongiosum with furcate (instead of emarginate) processes.

Empty cell of S. spongiosum in rear view showing distribution of emarginate processes.