Phylum: Charophytra   Family: Desmidiaceae

Cosmarium paragranatoides H.L. Skuja 1930

The seemingly identical Cosmarium difficile var. subimpressulum Messikommer 1927 has now been synonymised. It differs from Cosmarium difficile in having a small protuberance.
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.