Phylum: Charophyta Family: Closteriaceae
Closterium closterioides var. intermedium (J. Roy & Bisset) Ruzicka 1973
The only different between this variety and the nominate is the size, being less than half. An acidophile that tolerated very slightly alkaline conditions. Found in peaty pools and loch-margins with vegetation. It's much rarer than the nominate.
References:
Ruzicka, J. (1973) Die Zieralgen der Naturschutzgebietes "Rezbinec" (Südböhmen).
Brook, A.J. & Williamson, D.B. (2010) A Monograph on some British Desmids.
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.