Phylum: Charophyta   Family: Desmidaceae

Closterium jenneri J. Ralfs 1848

Much has been written regarding the similarities with Cl. cynthia. The latter supporting girdle-bands and striae, while Cl. jenneri is lacking (although some authors suggest faint striae are sometimes noted).
Cell dimensions: L: 55-104 µm; B: 9-14 µm; Ap: 2.9-3.7 µm; Arc: 140-167; L/B: 6-8.
Cl. jenneri is proving to be rather scarce in the Outer Hebrides. The few finds so far are from circumneutral, mesotrophic, waters.

References: 
Brook, A.J. & Williamson, D.B. (2010). A Monograph on some British Desmids.
Coesel, P.F.M. & Meesters, K.J. (2023 second edition). Desmids of the Lowlands.