Phylum: Charophyta   Family: Desmidiaceae

Cosmarium subtumidum  Nordstedt

Widespread but not particularly common in acidic bogs and moorland pools

References: 
Coesel, P.F.M. & Meesters, K.J. (2007) Mesotaeniaceae and Desmidiaceae of the European Lowlands
John, D.M. & Williamson, D.B. (2009) A Practical Guide to the Desmids of the West of Ireland
West, W. & West, G.S. (1905) A Monograph of the British Desmidiaceae, Volume 2