A multivariate analysis of taxonomic limits in Diplolaemus Bell 1843
The gemís Diplolaemus Bell, 1843 is a common squamate component of the Patagonian región of South América. Considerable taxonomic confusión exists within this gemís, particularly about the status of Chilean-Andean populations and the actual distribution of D. leopardinas (Werner, 1898). In an attempt to clarify the taxonomic status and distribution of Diplolaemus species, we performed a principal component analysis (PCA) and discriminant function analysis (DFA) using both standard morphometric and meristic data. Multivariate summaries of morphometric data show that most species are poorly discriminated, with the exception of D. darwinii. In contrast, a PCA analyses performed on the meristic data clearly distinguish three discrete groups: 1. D. darwinii, 2. D. sexcinctus including the Chilean populations, and 3. populations from Mendoza, Argentina, including the holotype of D. leopardinus and of D. bibronii. A DFA consistently assigned with a high percentage of successful classifcation (95%) individuals of the species D. darwinii, D. sexcinctus, and D. bibronii. The group with lowest successful rate in the cross validation procedure (78%) was D. leopardinus (including populations from Mendoza), with misidentifcations assigned only to D. bibronii. The group formed by Mendoza populations and the holotype of D. leopardinus is visibly distinct from remaining D. bibronii in colour patterns. The holotype of D. leopardinus is clearly differentiated from the Chilean-Andean populations. Our results support the assignment of populations from Mendoza to D. leopardinus, and suggest that the Chilean-Andean populations currently assigned to this taxon should be referred as D. sexcinctus, together with populations from the Argentinean provinces of Río Negro and Neuquén.