Phylum: Charophyta Family: Desmidiaceae
Cosmarium formosulum Hoff 1888
Widespread and rather common in slightly acidic to mildly alkaline waters. The granulation of the central tumour is variable.
References:
Kouwets, F.A.C. (in manuscript) European Flora of the Desmid Genus Cosmarium.
West, W. & West, G.S. (1908) A Monograph of the British Desmidiaceae, Volume 3.
John, D.M. & Williamson, D.B. (2009) A Practical Guide to the Desmids of the West of Ireland.
Coesel, P.F.M. & Meesters, K.J. (2007) Mesotaeniaceae and Desmidiaceae of the European Lowlands.