Identificação Morfológica e Molecular de Duas Espécies de Geophagus (Cichliformes: Cichlidae) do Rio Tocantins, Brasil

Abstract

The target species of this study, Geophagus neambi and Geophagus sveni, are sympatric and syntopic species and are part of a recent problem in the Tocantins River. Prior to the description of G. neambi and G. sveni, individuals of Geophagus in the Tocantins River basin were identified nominally as G. surinamensis, G. altifrons and even attributed to Geophagus cf. proximus, due to the similarity of several traits shared by these species of the 'Geophagus' complex. Although the description of G. neambi and G. sveni has limited the distribution of both species to the Upper Tocantins and some localities of the middle Tocantins, the question of which species of Geophagus occur in the lower Tocantins region remained. Thus, the diversity of Geophagus in the Tocantins River is still little explored. Therefore, it became necessary to confirm the identity of G. neambi and G. sveni and their distributions along the Tocantins River, through identification, morphometry, and Single Locus Species Delimitation (SLSD) methods using the mitochondrial COI gene as a molecular marker. In this study, three aspects of integrative taxonomy were addressed: genetic, morphometric and the geographic distribution of two species of the genus Geophagus sensu stricto Heckel 1840, family Cichlidae. The SLSD methods were effective in delimiting the species and suggested the existence of molecular entities in G. neambi. The distribution of G. neambi and G. sveni is wider than initially recorded, expanding the sympatry area of this species in the lower Tocantins River. It was not possible to confirm the occurrence of G. altifrons, G. proximus, and G. surinamensis in the Tocantins River, making G. neambi and G. sveni the only valid species of Geophagus occurring in the upper, middle, and lower Tocantins River regions.