Phylum: Charophyta   Family: Desmidiaceae

Cosmarium horizontale (W. Schmidle) F.A.C. Kouwets 1997

There are a number of these 'dumbbell-like' cells, which probably comprise a complex. This species should be compared with the similar but larger C. swieri F.A.C. Kouwets 2025, both species enjoy the same habitat-type and have been found together in the same loch.
Cell dimensions (2): L: 38.7-39 µm; B: 22.4-22.7 µm; Is: 13.9-14 µm; L/B: 1.71-1.75.
A possibly widespread but rarely recorded taxon. The Outer Hebridean finds have come from an acidic, meso-oligotrophic, loch.

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