Phylum: Charophyta   Family: Desmidiaceae

Cosmarium confusopraemorsum F.A.C. Kouwets 2025

This recently named species is based on West & West’s (1908: 196) concept of Cosmarium praemorsum Brébisson 1856. Brébisson’s (1856) original description and figure are poor, so Kouwets (2025) has left it as a species inquirenda. Chloroplast with two pyrenoids but occasionally with one. This is one of the larger granulate species.
Cell dimensions: L: 41-54 µm, B: 38-48 µm, Is: 13-16 µm; Th: 23-30 µm, L/B: 1.01-1.22.
Because of taxonomic confusion, its status is unclear. In the Outer Hebrides, it is infrequently recorded.

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