Phylum: Charophyta   Family: Desmidiaceae

Staurastrum pingue var. planctonicum (Teiling) Coesel & Meesters 2013

Better known as Staurastrum planctonicum, it has recently been reduced to a variety. Widely distributed and not uncommon in circumneutral waters, usually with plankton

References: 
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus
John, D.M. & Williamson, D.B. (2009) A Practical Guide to the Desmids of the West of Ireland