Phylum: Charophyta   Family: Desmidiaceae

Staurastrum crassangulatum Coesel

A benthic and planktonic species in circumneutral waters. Not thought to be scarce but distribution is vague

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