Phylum: Charophyta   Family: Desmidiaceae

Cosmarium botrytis J. Ralfs 1848

This species has spawned many varieties but the nominate variety is the most widespread. It is readily confused with similar taxa, with which it should be carefully compared.
Cell dimensions: L: 58-86 µm; B: 48-66 µm.; Is: 16-21 µm; Th: 33-37 µm, L/B: 1.10-1.30.
Rather common in slightly acidic to slightly alkaline waters, found in the plankton and marginal vegetation of lochs, and from atmophytic habitats.

References: 
Kouwets, F.A.C. (2025). European Flora of the Desmid Genus Cosmarium.
Van Westen, M.C. (2024). Sieralgen in Drenthe.