Phylum: Charophyta   Family: Desmidiaceae

Cosmarium granatum var. alatum (Jacobsen) Kurt Förster

It differs from the nominate variety by having smaller cells and the lower part of the semicells are straight to slightly divergent. Kouwets (in manuscript) regards this variety sufficiently distinct to warrant species status. Found in mesotrophic, circumneutral waters. Status in the Outer Hebrides unknown due to confusion with similar species.

References: 
Förster, K. (1965) Beitrag zur Desmidieen-Flora der Torne- Lappmark in Schwedisch-Lappland
Krieger, W. & Gerloff, J. (1962-9) Die Gattung Cosmarium
Kouwets, F.A.C. (in manuscript) European Flora of the Desmid Genus Cosmarium