The South American sun-spider genus Gaucha Mello-Leitão, 1924 is herein studied from a combined approach of cladistics and traditional taxonomy. This is the first cladistic analysis for a group of mummuciid solifuges, and it is pioneer in integrating traditional morphological characters with landmark data for inferring the phylogeny of any group of Solifugae. As a result, Gaucha is redefined and its monophyly demonstrated. Gaucha fasciata Mello-Leitão, 1924, type species of this formerly monotypic genus, is redescribed based on specimens from the type locality, in Rio Grande do Sul, Brazil. Three new species are described from Brazil: Gaucha avexada sp.nov. from Bahia and Tocantins, Gaucha curupi sp.nov. from Rio Grande do Sul, and Gaucha eremolembra sp.nov. from Minas Gerais. A fourth new species, Gaucha casuhati sp.nov., is described from Buenos Aires province, Argentina. In addition, Metacleobis Roewer, 1934 and Gauchella Mello-Leitão, 1937 are synonymized with Gaucha, following the examination of the type specimens and based upon evidence from the cladistic analysis. Gaucha fulvipes (Roewer, 1934) comb.nov., from Mato Grosso (Brazil), is therefore proposed, whereas Gaucha stoeckeli Roewer, 1934 comb.rest., from Luribay (Bolivia), is restored into its original name combination. Gaucha ibirapemussu (Carvalho et al., 2010) comb.nov. and Gaucha mauryi (Rocha, 2001) comb.nov., from the Brazilian states of Piauí and Bahia, are also transferred, from Mummucia Simon, 1879. Gaucha is here defined, among other characters, by the large size of the cheliceral movable finger MP tooth as compared to MM tooth, and by the presence of a pronounced gnathal edge carina on the movable finger mucron of males. Two speciesgroups are herein defined within the genus: the fasciata group, for G. casuhati sp.nov., G. curupi sp.nov., G. fasciata, G. fulvipes comb. nov. and G. stoeckeli comb.rest., and the ibirapemussu group, for G. avexada sp.nov., G. eremolembra sp.nov., G. ibirapemussu comb. nov. and G. mauryi comb.nov. A key to the identification of Gaucha species is included.