Phylum: Charophyta   Family: Desmidiaceae

Cosmarium venustum  (Brébisson) W. Archer

Widespread in the British Isles in peaty pools, often with Sphagnum. Many varieties have been added over time which has stretched the boundaries somewhat. Kouwets (in manuscript) will address these issues.

References: 
Kouwets, F.A.C. (in manuscript) European Flora of the Desmid Genus Cosmarium
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. (1908) A Monograph of the British Desmidiaceae, Volume 3