Cosmarium impressulum
Image © Alfred van Geest

Cosmarium impressulum. Notice semi-oblong semicells with some eight, rather faint, marginal undulations.
Cell dimensions (L x B): 20 x 14 µm



empty cell
Image © SEM image Hanny Kooijman née Van Blokland © IBED

SEM image of C. impressulum. Notice asymmetrical cell shape (and faintly scrobiculate wall).

 


Desmid of the month
March 2023

Cosmarium impressulum


Cosmarium impressulum belongs to the problematic group of small-sized Cosmaria with a smooth cell wall. Semicells are semi-oblong in outline marked by some eight, rather faint undulations. Often, cell outline is not very symmetrical: undulations may differ in an irregular way in size and expression. In the Netherlands, C. impressulum is a fairly common species in various meso-eutrophic water bodies.


Two other cells of C. impressulum showing an irregular undulation of the cell outline.

C. impressulum
Image © Alfred van Geest

C. impressulum
Image © Alfred van Geest