Phylum: Chlorophyta   Family: Desmidiaceae

Cosmarium subpunctulatum C.F.O. Nordstedt 1887

Since Norstedt named this species, more recent authors have moved it to a variety of C. punctulatum. However, that species is thought to have doubtful and ill-defined characteristics. Similar to other small, smooth-walled Cosmaria. Note the median inflation of large granules (but lacking a supraisthmial granule found in C. discrepans).
Cell dimensions: L: 30-38 µm; B: 28-35 µm; Is: 10-13.2 µm; Th: 20-24 µm; L/B: 1.0-1.08.
Common, found in moorland pools and bogs, acidic or neutral.

References: 
Kouwets, F.A.C. (2025). European Flora of the Desmid Genus Cosmarium.
Van Westen, M.C. (2024). Sieralgen in Drenthe.
West, W. & West, G.S. (1908). A Monograph of the British Desmidiaceae, Volume 3.