Phylum: Charophyta Family: Desmidiaceae
Cosmarium polygonatum Halász 1940
Infrequent in peaty pools and disused peat cuttings but possibly overlooked. These small cells are readily confused with similar species.
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.