Phylum: Charophyta   Family: Closteriaceae

Closterium pseudolunula O. Borge 1909

First described and illustrated by Borge (1909: 3, pl. 1: 2).
Cell dimensions: L: 240-330 µm; B: 30-40 µm; Ap: 6-7 µm; L/B: 6-8.
A species of circumneutral waters of little-known distribution in the Outer Hebrides.

References: 
Borge, O. (1909). Nordamerikanische Susswasseralgen.
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.
Van Westen, M. (2024). Sieralgen in Drenthe.