Phylum: Charophyta   Family: Desmidiaceae

Cosmarium lamouraense F.A.C. Kouwets 2025

A newly described species that is similar to another newly described species: C. perdepressum, which in turn are similar to the doubtful C. bioculatum var. depressum (G. Schaarschmidt) W. Schmidle 1894. It is also worth comparing it with the C. phaseolus J. Ralfs 1848 complex, although that group has dilated sinuses giving a reduced reniform shape to the semicells.
Cell dimensions: L: 19-22.8 µm, B: 18.6-22.4 µm, Is: 5.4-6.9 µm; Th: 9.3-11.1 µm, L/B:1.00-1.09.
Found in slightly acidic, mesotrophic, waters. It’s status in the Outer Hebrides is unclear due to earlier taxonomic confusion.

References: 
Kouwets, F.A.C. (2025). European Flora of the Desmid Genus Cosmarium.