Systematic revision and phylogeny of the South American sun-spider genus Gaucha Mello-Leitao (Solifugae: Mummuciidae), with description of four new species and two new generic synonymies

The South American sun-spider genus Gaucho Mello-Leith, 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, Gaucho is redefined and its monophyly demonstrated. Gaucha, fasciata Mello-Leitao, 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: Gaucho avexada sp.nov. from Bahia and Tocantins. Gaucho curupi sp.nov. from Rio Grande do Sul. and Gaucho eremolembra sp.nov. from Minas Gerais. A fourth new species, Gaucho casuhati sp.nov., is described from Buenos Aires province, Argentina. In addition, Metecleobis Roewer, 1934 and Gauchella Mello-Leitao, 1937 are synonymized with Gaucho, following the examination of the type specimens and based upon evidence from the cladistic analysis. Gaucho fulvipes (Roewer, 1934) comb.nov., from Mato Grosso (Brazil), is therefore proposed, whereas Gaucho stoeck-eli Roewer. 1934 comb.rest., from Luribay (Bolivia), is restored into its original name combination. Gaucho ibirapemussu (Carvalho et al.. 2010) coinb.nov. and Gaucha, mauryi (Rocha, 2001) comb.nov., from the Brazilian states of Piaui and Bahia, are also transferred, from Mummucia Simon, 1879. Gaucho 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 canna on the movable finger mucron of males. Two species groups are herein defined within the genus: the fizsciata 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.now.. G. ibirapemussu comb. now. and G. mauryi comb.nov. A key to the identification of Gaucho species is included.