Phylum: Charophyta   Family: Desmidiaceae

Cosmarium ellipsoideum F. Elfving 1881

First described and illustrated by Elfving (1881: 13, pl. 1: 10). West & West (1902: 40, pl. 2: 10) made it a variety of C. contractum, which is a large, confused, complex. Coesel & Meesters (2023: 145) have reinstated it to its original designation.
Cell dimensions: L: 25-36 µm, B: 17-27 µm, Is: 5-8 µm; Th: 14-18 µm, L/B: 1.3-1.5.
Infrequently recorded in nutrient-poor lochs and bogs of the north-west of Scotland.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition). Desmids of the Lowlands.
Elfving, F. (1881). Anteckningar om Finska Desmidiéer.