Phylum: Charophyta   Family: Desmidiaceae

Xanthidium antilopaeum var. crameri Grönblad 1921

This cell is characterised by being a little smaller than the nominate, having rounded basal angles, two separated lateral spines and closely paired apical spines. The long spines have some curvature. As with the nominate variety it displays a degree of polymorphism, well noted in Förster's drawings (1973, p. 563, taf.19). A rare desmid with a nearctic and north-western palearctic distribution from Alaska to Florida and Arctic to northern Europe.

References: 
Förster, K. (1973) Desmidieen aus dem Südosten der Vereinigen Staaten von America.
Prescott, W.G. et al. (2001 reprint) A Synopsis of North American Desmids. Part II, Desmidiaceae: Placodermae, Section 4.
Palamar-Mordvintseva, G.M. (1982) Manual for identification of the freshwater algae of the USSR. Desmidiales (in Russian).