Phylum: Charophyta   Family: Desmidiaceae

Cosmarium fabiforme F.A.C. Kouwets 2025

Similar is size to the recently described Cosmarium alteroreniforme F.A.C. Kouwets 2025, but that species has larger granules and a noticeably raised apex.
Single cell dimensions: L: 54.9 µm; B: 48.3 µm; Is: 18 µm; L/B: 1.14.
This sample came from semi-permanent rainwater pools in a disused quarry with a neutral pH.

References: 
Kouwets, F.A.C. (2025). European Flora of the Desmid Genus Cosmarium. Part 1: Text. Part 2: Plates.