Phylum: Charophyta   Family: Desmidiaceae

Cosmarium pyramidatum Brébisson ex Ralfs

Common in peaty pools and bogs, also in rocky pools and lochs. There is a considerable size range with this species which may involve more than one species

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
John, D.M., Whitton, B.A. & Brook, A.J. (2011 second edition) The Freshwater Algal Flora of the British Isles