Cosmarium connatum. Notice large dimensions, shallow sinus and subcircular semicells.
Cell dimensions (L x B): 96 x 66 µm

Dead, largely empty cell of C. connatum showing distinct cell wall pore fields



Desmid of the month
August 2018

Cosmarium connatum

Cosmarium connatum is a pretty large-sized, smooth-walled species, characterized by a shallow sinus and subcircular semicells. In apical view, semicells are broadly elliptic to almost circular. Chloroplasts contain two pyrenoids and the cell wall is marked by distinct pore fields. In the Netherlands, C. connatum is rather common in mesotrophic quaking fen hollows but elsewhere rare.

Same cell of C. connatum in apical view showing a broadly elliptic outline and two pyrenoids.

Another cell of C. connatum in frontal view. Notice two pyrenoids in each of the chloroplasts.

SEM picture of C. connatum.