A molecular phylogenetic analysis in Gymnotus species (Pisces: Gymnotiformes) with inferences on chromosome evolution

A phylogenetic analysis using 345 nucleotides sequenced from the mitochondrial gene ND2 was carried out in the four Gymnotus species from the Upper-Parana river system, Southeastern Brazil, G. carapo, G. pantherinus, G. inaequilabiatus, and G, sylvius. A phylogeny is proposed in which G, pantherinus is located as the most basal lineage within the group. G. carapo and G, sylvius line ages present the most recent divergence; G. inaequilabiatus is the closest sister group in relation to G. carapo and G. sylvius. New hypotheses of chromosome evolution in this group of fish are proposed based on the phylogenetic tree reconstructed using the sequence data. After an appraisal of karyotype data for species phylogeny inferences, we suggest that karyotype data are useful for the early steps of phylogenetic and chromosome evolution studies, and that the conjugation of molecular and karyological approaches can improve the hypotheses formulation.