Phylum: Charophyta   Family: Desmidiaceae

Staurastrum forficulatum var. verrucosum R. Grönblad 1920

First described and illustrated by Grönblad (1920: 64, pl. 3: 47, 50, 51). A variable species with two varieties based largely on the length of the lateral spines.
Cell dimensions: L. 30-60 µm, B. 30-60 µm, Is. 10-13 µm.
Found in acidic moorland and upland pools. Scarce in the Outer Hebrides.

References: 
Coesel, P.F.M. & Meesters, K.J. (2013). European Flora of the Desmid Genera Staurastrum and Staurodesmus.
Grönblad, R. (1920). Finnländische Desmidiaceen aus Keuru.