Phylum: Charophyta   Family: Desmidiaceae

Cosmarium carniolicum (J. Lütkemüller) F.A.C. Kouwets 2025

Part of the C. pseudopyramidatum complex. The main characteristics are a single large pyrenoid and straight to concave sides to the semicells.
Cell dimensions: L: 48-53 µm; B: 29-32 µm; Is: 11.9-12.8 µm; L/B: 1.61-1.86.
Due to earlier confusion with similar taxa, the distribution is unknown. However, the habitat requirements of acidic oligo-mesotrophic waters such as moorland pools and bogs are plentiful in the Outer Hebrides.

References: 
Kouwets, F.A.C. (2025). European Flora of the Desmid Genus Cosmarium.