Phylum: Charophyta Family: Desmidiaceae
Cosmarium ralfsii var. montanum Raciborski
Widespread in acidic conditions but not particularly common. This variety is mainly distinguished by the open sinuses; it can also have produced basal angles but this feature in not always apparent
References:
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
West, W. & West, G.S. (1905) A Monograph of the British Desmidiaceae, Volume 2