Phylum: Charophyta   Family: Desmidiaceae

Cosmarium botrytis var. gemmiferum (L.A. de Brébisson) C.F.O. Nordstedt 1888

First described by Brébisson (1856: 301) but without illustration. It was later moved by Nordstedt (1888: 191) as a variety of Cosmarium botrytis. [This equates to Cosmarium gemmiferum L.A. de Brébisson 1856, sensu W. & G.S. West (1912: 5, pl. 97: 4)]. For a detailed analysis see Kouwets (in manuscript) who is proposing a new name. The only, but significant, difference from the nominate variety is the pronounced central inflation, seen best in apical view. The zygospore, illustrated below, hasn't been described before. It would appear indistinguishable from the nominate variety. One of the attached gametangial cells in apical view shows this broad inflation and concentric granules well.
Cell dimensions: L: 65-89 µm; B: 54-72 µm.; Is: 14-24 µm; Th: 32-42 µm, L/B: 1.18-1.30.
Zygospore: Overall diameter: 73-77; Projections: 9-11.
Distribution unknown as it requires apical views to identify it. Found in slightly alkaline waters, in ephemeral winter floods.

References: 
Brébisson, L.A. de (1856) Liste des Desmidiées, observées en Basse-Normandie.
Kouwets, F.A.C. (in manuscript) European Flora of the Desmid Genus Cosmarium.
Nordstedt, C.F.O. (1888) Desmidieer fran Bornholm, samlade och delvis destämda af R.T. Hoff, granskade af O. Nordstedt.