Phylum: Charophyta   Family: Desmidiaceae

Staurastrum pileolatum  Brébisson

An upland species of acidic bogs. A rare species in Britain

References: 
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus
West, W. & West, G.S. (1912) A Monograph of the British Desmidiaceae, Volume 4
Ralfs, J. (1848) The British Desmidieae