Phylum: Charophyta   Family: Desmidiaceae

Cosmarium pseudosphagnicola F.A.C. Kouwets 2025

There are several confusingly small cells that display four granules in an asymmetric configuration. However, the granules can be faint or even lacking and difficult to see with a light microscope. With more research it may be possible to separate some of them on habitat preferences.
Cell dimensions (3): L: 7.5-9.3 µm; B: 7.8-9.8 µm; Is: 2.3-3.6 µm; Th: 4.2 µm; L/B: 0.87-0.97.
Found in slightly acidic to mildly alkaline waters. Distribution in the Outer Hebrides unknown due to earlier confusion with similar species.

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