Cosmarium tetraophthalmum
image © Alfred van Geest

Cosmarium tetraophthalmum. Notice about pyramidal semicells with a granulate wall.
Cell dimensions (L x B): 120 x 85 µm



 


Desmid of the Month
November 2025

Cosmarium tetraophthalmum


Cosmarium tetraophthalmum should be compared with C. botrytis (desmid of September 2013). Just like that latter species, C. tetraopthalmum is characterized by pyramidal semicells the wall of which is evenly covered with rather closely spaced granules. Compared with C. botrytis, however, cells in C. tetraophthalmum are larger and marked by a higher length to breadth ratio. In the Netherlands it is occasionally encountered in benthos and tychoplankton of mesotrophic water bodies, particularly fen hollows.

C. tetraophthalmum
image © Alfred van Geest (mouse-over)

Empty cell of Cosmarium tetraophthalmum, showing evenly spaced granules with pores in between (mouse-over).

Cosmarium tetraophthalmum
image © Alfred van Geest

Another cell of Cosmarium tetraophthalmumshowing two clearly lined pyrenoids in each semicell.