Phylum: Charophyta   Family: Desmidiaceae

Cosmarium phaseolus var. elevatum  Nordstedt 1873

Widespread, but would appear quite scarce. Found in plankton, moorland pools and bogs

References: 
Coesel, P.F.M. & Meesters, K.J. (2007) Mesotaeniaceae and Desmidiaceae of the European Lowlands
West, W. & West, G.S. (1905) A Monograph of the British Desmidiaceae, Volume 2