Phylum: Charophyta Family: Desmidiaceae
Staurastrum diacanthum A. Lemaire
Closely related to Staurastrum paradoxum, it is characterised by large spines at the base of the processes. Distribution is unclear 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
Tsarenko, P.M., Wasser, S.P. & Nevo, E. editors (2014) Algae of Ukraine, Volume 4: Charophyta