Phylum: Charophyta   Family: Desmidiaceae

Cosmarium swieri F.A.C. Kouwets 2025

There are a number of these 'dumbbell-like' cells, which probably comprise a complex. This one has been renamed by Kouwets (2025) after C. isthmium f. hibernicum West 1892, which was found in Co. Galway, Ireland by Swier Oosterhuis and named after him.
Single cell dimensions: L: 49-49.6 µm, B: 31-31.6 µm, Is: 18 µm; L/B:1.57-1.58.
The most likely habitat is oligo-mesotrophic lochs and lochans, also boggy pools. The Outer Hebridean finds were from the shallow, silty, margin of a small loch. A very rare desmid with probably an Atlantic-subarctic distribution.

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