Cell of Cosmarium fontigenum. Notice broadly trapeziform semicells with a slightly produced apex.
Cell dimensions (L x B): ca 23 x 23 µm

C. fontigenum in apical view showing a semicell with an ellipsoid outline and a slight median inflation.

Empty cell of C. fontigenum, showing widely spaced cell wall pores.


Desmid of the month
March 2024

Cosmarium fontigenum

Cosmarium fontigenum is a rather small-sized, smooth-walled Cosmarium species readily to be recognized by its characteristic semicell outline: broadly trapeziform with an undulation in the upper part of the lateral sides giving rise to a somewhat produced apex. In the Netherlands, C. fontigenum is of incidental occurrence in mesotrophic, circumneutral water bodies.

Another cell of C. fontigenum, showing a single, central pyrenoid in each semicell.

SEM picture of C. fontigenum showing cell wall pores with props of mucilage.