Phylum: Charophyta   Family: Desmidiaceae

Staurastrum tetracerum var. irregulare (West & G.S. West) A.J. Brook

The Wind Farm sample was from an acidic moorland pool where this variety was frequent and all those examined were triradiate. It is also known from more circumneutral waters. Brook (1982) described a collection from Wales: "… differing from S. tetracerum in that its processes tend to be longer, and especially in that the cell body possesses a wide, open sinus. ... In many specimens there are prominent granules, or occasionally a spine, at each corner of the semicell body where it bends sharply above the isthmus to join the base of each process."

References: 
Brook, A.J. (1982) Desmids of the Staurastrum tetracerum-group from a eutrophic lake in mid-Wales
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus