Phylum: Charophyta   Family: Desmidiaceae

Staurastrum cyrtocerum var. brachycerum (Brébisson) Coesel & Meesters

A short stocky variety with length and breadth about equal. Found in mainly acidic habitats such as moorland pools and Sphagnum bogs

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