Phylum: Charophyta   Family: Desmidiaceae

Staurastrum pingue var. planctonicum (E. Teiling) P.F.M. Coesel & K.J. Meesters 2013

First described and illustrated by Teiling (1946: 77, figs 30, 32) as Staurastrum planctonicum and still better known by this name. Recently, Coesel & Meesters (2013: 133, pl. 103: 5-7; pl. 104: 1-3) made it a variety of Staurastrum pingue without comment.
Overall cell dimensions: L: 30-110 µm; B: 30-110 µm; Is: 10-12 µm.
Widespread and fairly common in circumneutral to slightly acidic waters, such as in the plankton of lochs and marginal vegetation of moorland pools.

References: 
Coesel, P.F.M. & Meesters, K.J. (2013). European Flora of the Desmid Genera Staurastrum and Staurodesmus.
Teiling, E. (1942). Schwedische Planktonalgen 3. Neue oder wenig bekannte Formen.