Phylum: Charophyta   Family: Desmidiaceae

Cosmarium contractum Morpha 2 F.A.C. Kouwets 2025

The Morpha 2 status is a holding position pending more research. It’s based on Grönblad’s (1960: 37, figs 42-44, 47-48, photo 16) interpretation. I refer you to Kouwets (2025: 147) for a detailed analysis of the C. contractum complex.
Cell dimensions: L: 38.8-49.8 µm; B: 28.3-34.3 µm; Is: 7.9-11.9 µm; Th: c.16; L/B: 1.38-1.46.
An acidophile found in oligo-mesotrophic waters such as moorland pools and lochs. Distribution is difficult to evaluate due to the complex nature of this group.

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