Phylum: Charophyta   Family: Desmidiaceae

Cosmarium luxuriosum (F.A.C. Kouwets) P.F.M. Coesel 1989

This is similar in outline to Cosmarium margaritiferum Ralfs 1848, but is readily distinguished by a series of large, rounded granules at the apical angles. They occupy the same habitat type.
Cell dimensions: L: 54.9-56 µm; B: 46.2-48.6 µm; Is: 17.8-18.1 µm; Th: c.36-38 µm; L/B: 1.19.
Found in boggy moorland pools and abandoned peat-cuttings. There are few records and is probably genuinely rare.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition). Desmids of the Lowlands.
Kouwets, F.A.C. (2025). European Flora of the Desmid Genus Cosmarium. Part 1: Text. Part 2: Plates