Análise da variação geográfica em Neusticurus ecpleopus cope, 1876 (Reptilia: Gymnophthalmidae)

Abstract

Neusticurus ecpleopus has a disjunct distribution in southern Amazônia, with a gap in its distribution between the Ituxi and Tapajós rivers. Some studies have already pointed out the existence of variation among populations. However, so far there is no evidence that the species is polytypic, or even that it represents a group of species. The present study compares samples from several populations, seeking to re-evaluate the taxonomic status of the species. Samples from six populations were studied: (1) three east of the Tapajós River - Serra Norte, Carajás; Cachoeira Juruá, Xingu; Agropecuária Treviso, Curuá-Una River; all in Pará; (2) three west of the Ituxi River - Porto Walter, Juruá River, AC; six localities in Peru; and Santa Cecília, Ecuador. A total of 28 characters were studied, including cephalic shield, dorsal and ventral body scales, precloacal shield, and digits. A discriminant function analysis (DFA) was performed, from which a first indication of possible population differences was obtained. Non-variable characters were excluded from the analysis, as was the number of femoral pores, as it exhibited sexual dimorphism. For all symmetrical traits, the sum of both sides was considered. The correlation graph of factors 1 and 2 indicated the presence of three clusters of populations: (1) Acre; (2) Santarém and Marabá; (3) Peru, Ecuador and Xingu. The main characteristics responsible for these groupings were the number of supralabials and postínfralabiaís, in factor 1; and paravertebral tubercles, number of ínfralabiaís and suboculars in factor 2. It is possible that some of these groupings resulted from a bias in the discriminant analysis. These results, therefore, are still preliminary, and need to be analyzed using other statistical tests.