Phylum: Charophyta   Family: Desmidiaceae

Staurastrum hirsutum var. pseudarnellii P.F.M. Coesel & K.J. Meesters 2013

First described and illustrated by Coesel & Meesters (2013: 106, pl. 50: 9-12). It differs from the nominate variety by enlarged granules on the basal angles.
Cell dimensions: L. 35-55 µm, B. 30-50 µm, Is. C.10 µm.
Found in acidic oligotrophic pools and ditches. Status in the Outer Hebrides unknown.

References: 
Coesel, P.F.M. & Meesters, K.J. (2013). European Flora of the Desmid Genera Staurastrum and Staurodesmus.