Phylum: Charophyta Family: Desmidiaceae
Cosmarium abbreviatum var. planctonicum West & G.S. West
Slightly larger than the nominate and with convex apices. Found in circumneutral waters, usually in the plankton of deeper lochs
References:
Coesel, P.F.M. & Meesters, K.J. (2007) Mesotaeniaceae and Desmidiaceae of the European Lowlands
West, W. & West, G.S. (1908) A Monograph of the British Desmidiaceae, Volume 3
Tsarenko, P.M., Wasser, S.P. & Nevo, E. editors (2014) Algae of Ukraine, Volume 4: Charophyta