Análise Morfométrica de Gymnotus inaequilabiatus (Valenciennes, 1839) (Gymnotiformes: Gymnotidae) em Diferentes Bacias Hidrográficas Brasileiras

Abstract

The Gymnotiformes are usually known as electric fishes, knife fishes, tuvira or morenitas, constituting a small and endemic portion of the Neotropical ichthyofauna. Among your genus, by presenting a broad geographic distribution and  high richness, Gymnotus is the most studed. One of the species that more stands out is the Gymnotus inaequilabiatus wich is distributed in the Parana-Paraguai, Coastal Rivers, Uruguay and Brazilian southeastern Rivers Basins. Based in reports of molecular divergences and introduction of this specie in several drainage basins, was traced a hypothesis that exists morphologic variation between populations of G. inaeaquilabiatus from different river basins. To evaluation and interpretation of the morphometric data were realized of principal components analysis and canonical variable analysis. The analysis showed no significant differences between the populations of G. inaequilabiatus from the different river basins. However, the canonical variable analysis analysis presented a slight tendency in the separation of the populations. The results show that Gymnotus inaequilabiatus not differ morphologically and that there is no possibility of the taxonomy inference about populations of the analyzed basins, no corroborating with the initial hypothesis. However, suggests that G. inaequilabiatus has a high adaptive capacity, great capacity for colonization and resistant to different environmental pressures. Keywords: upper Parana river, morphology; knife fish; electric fish; Paraguai river.