Phylum: Charophytra   Family: Desmidiaceae

Cosmarium paragranatoides H.L. Skuja 1930

This taxon differs from the similar C. difficile in having a small protuberance. It’s a variable species morphologically and is well illustrated by Kouwets 92025) with numerous drawings.
Single cell dimensions: L: 24.6 µm; B: 17 µm; Is: 4 µm; Th: 13 µm; L/B: 1.45.
Found in mesotrophic, acidic, habitats such as moorland pools and vegetated lochs. The status in the Outer Hebrides is uncertain due to taxonomic confusion but it would appear to be rare.

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