Phylum: Charophyta   Family: Desmidiaceae

Cosmarium troumousense F.A.C. Kouwets 2025

This newly described species is part of a complex of similar-looking taxa. As the name suggests, it’s rather similar to C. pseudotroumousense but on average, slightly smaller.
Cell dimensions: L. 26.6-29.2 µm; B. 22.4-24.6 µm; Is. 9.1-10.3 µm; Th. 13.8-14.8 µm; L/B. 1.17-1.25. The status is unknown in the Outer Hebrides. In Europe it has been found with moss-cushions in spring bogs and with moss on dripping rocks. The Outer Hebridean finds have also come from dripping rocks.

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