Phylum: Charophyta   Family: Desmidiaceae

Cosmarium klebsii R. Gutwinski 1892

Semicells are subpyramidal with broadly rounded basal angles and a truncate apex. The sinus is dilated at the apex then closed for two-thirds of the length. The smooth wall is covered in fairly large mucus pores, which are randomly spread. There is a supraisthmial row, which seems a consistent feature. There is currently quite a size-range, which may indicate more than one taxon is involved.
Cell dimensions: L: 33.8-38.7 µm, B: 29.6-37.4 µm, Is: 10.8-11.7 µm; Th: c.18-19.6 µm; L/B: 1.04-1.15.
The distribution is unclear as it has been confused with other species in the past. Current finds have come from oligo-mesotrophic, circumneutral waters such as shallow loch-margins with aquatics.

References: 
Kouwets, F.A.C. (2025) European Flora of the Desmid Genus Cosmarium. Part 1: Text. Part 2: Plates.