Phylum: Charophyta   Family: Desmidiaceae

Cosmarium moniliforme var. limneticum W. & G.S. West 1908

It differs only slightly in size from the nominate variety, mainly in its broader and wider isthmus. West & West (1908) also note: “It is readily distinguished by the slight angularity of the apices and the wide isthmus.” However, other authors have pointed out that this angularity also occurs when cell-division has just taken place.
Cell dimensions: L: 28.4-31.6 µm; B: 17.3-18.6 µm; Is: 11.4-12.2; L/B: 1.65-1.71.
In the Outer Hebrides it has been found in silty loch-margins, and boggy moorland pools in slightly acidic to slightly alkaline habitats. It is infrequently recorded.

References: 
Kouwets, F.A.C. (2025). European Flora of the Desmid Genus Cosmarium. Part 1: Text. Part 2: Plates.
West, W. & West, G.S. (1908). A Monograph of the British Desmidiaceae, Volume 3.