The crafty vesper mouse (Calomys callidus) is a species of rodent in the family Cricetidae. It is found in Argentina and Paraguay.
References
Musser, G. G. and M. D. Carleton. 2005. Superfamily Muroidea. pp. 894–1531 in Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. M. Reeder eds. Johns Hopkins University Press, Baltimore.