Muruaga, N. B.; M. R. Figueroa Romero† & R. Kiesling. 2008. Circumscription of Rebutia minuscula (Cactaceae, Cactoideae). Darwiniana 46(2): 318-327. Species of Rebutia are distributed from northwestern Argentina to southern Bolivia (Cochabamba to Tarija). Five species grow in Argentina, including the type species of the genus: R. minuscula. The phenotypic diversity, very variable within the species of Rebutia, promoted the publication of nume- rous specific and infraspecific names, leading to considerable confusion in nomenclature, synonymy, and distinctive characters of its species, particularly for R. minuscula, whose delimitation overlaps with that of R. wessneriana. The aim of this work is to reevaluate the circumscription of R. minuscu- la. Exo-micromorphological characteristics of natural populations growing in the upper mountain forest and high-grasslands of Catamarca, Tucuman, Salta and Jujuy provinces, were analyzed. Data were documented with illustrations and photographs; information of geographic distribution is provi- ded as well as ecological and phenological observations. Synonyms are included and the nomenclatu- ral types for some of them are established. Rebutia wessneriana is considered as subspecies of R. minuscula and a new combination and a new rank is proposed: Rebutia minuscula subsp. wessneria- na.