Phylum: Charophyta   Family: Desmidiaceae

Staurodesmus omearae (W. Archer) Teiling

An acidophile, probably common in moorland bogs, pools, and disused peat-cuttings. More data is needed for the Outer Hebrides

References: 
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus
Kouwets, F.A.C. (1999) A check-list of desmids (Chlorophyta, Zygnemaphyceae) of France