Phylum: Charophyta   Family: Desmidiaceae

Cosmarium galeritum  C.F.O. Nordstedt 1870

First described and illustrated by Nordstedt (1870: 209, pl. 3: 26) from Brazil. Unfortunately, his rather depressed image doesn’t quite match the description. Therefore, West & West’s (1905:194) concept of British material is adopted.
Cell dimensions: L: 48-54 µm; B: 36-46 µm.; Is: 13-17 µm; Th: 22-25.6 µm; L/B: 1.23-1.38.
An infrequently recorded desmid, which, according to West & West (l.c.) is constantly found in upland areas. Hence, an Arctic-alpine distribution.

References: 
Kouwets, F.A.C. (in manuscript). European Flora of the Desmid Genus Cosmarium.
Nordstedt, C.F.O. (1870). Desmidiacae. [In] Warming, E. Symbolae ad floram Brasiliae centralis cognoscendam V.
West, W. & West, G.S. (1912). A Monograph of the British Desmidiaceae, Volume 4.