Phylum: Charophyta Family: Desmidiaceae
Cosmarium difficile Lütkemüller 1892
Widespread and common in moorland pools and Sphagnum bogs. A variable species both in size and shape. It may well represent more than one species.
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. (1912) A Monograph of the British Desmidiaceae, Volume 4