Cell of Cosmarium microsphinctum in frontal view. Notice pyramidal outline of semicells and relatively broad cell isthmus.
Cell dimensions (L x B): ca 40 x 27 µm


Desmid of the month
November 2023

Cosmarium microsphinctum

Cosmarium microsphinctum somewhat resembles C. cataractarum (desmid of January 2016). Cells have comparable dimensions, semicells are pyramidal in outline and the cell wall is remarkably punctate. Main difference is in the relative breadth of the cell isthmus: less than half the semicell breadth in C. cataractarum, more than half the semicell breadth in C. microsphinctum . In the Netherlands, C. microsphinctum was supposed to be rare but in recent years it is more often encountered in ephemeral puddles on sandy soil.

Cell of C. microsphinctum in apical view. Notice somewhat rhomboid shape of semicell.

Cell of C. microsphinctum (in oblique position) showing coarse punctation of cell wall.