Phylum: Charophyta   Family: Desmidiaceae

Staurodesmus triangularis var. brevispina (V. Allorge & P. Allorge) Coesel & Meesters 2013

Found in similar habitat to the nominate variety and seems just as infrequent. It differs in having the spines less that two-thirds the breadth of the cell-body.

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