Phylum: Charophyta   Family: Desmidiaceae

Staurodesmus controversus var. crassus (West & G.S.West) Coesel & Meesters 2013

Until recently, known as Staurodesmus crassus. Found in oligotrophic acidic waters. A rare species, most likely to be found in Atlantic regions.

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