CITOGENÉTICA COMPARATIVA E DIFERENCIAÇÃO GENÉTICA EM Neoplecostomus (SILURIFORMES: LORICARIIDAE) EM AFLUENTES DO RIO PARANÁ

Abstract

The Loricariidae family is one of the largest families of freshwater fishes, with 931 species distributed in 100 genera. Loricariidae members are popularly known as armored catfishes and characterized by a depressed body, covered by bony plates and a ventral sucker mouth. Inside the subfamily Neoplecostominae, the genus Neoplecostomus comprises small species that inhabit streams of south and southeast regions of Brazil. This genus is interested in genetic studies because they rarely migrate and can accumulate genetic differences between populations. Of the sixteen valid species described so far for this genus, eight were described for the Paraná river basin and there is evidence of new species occurring in this basin. Therefore, the objective of this study was to analyze the karyotype differentiation and genetic diversification in the genus Neoplecostomus from Iguaçu, Itararé, Cinzas and Tibagi river basins, with the goal of understand the karyotype evolution and biodiversity. The specimens were captured at four localities: Pinhão river (Neoplecostomus sp. 1), Samambaias river (Neoplecostomus cf. botucatu), Pedras river (Neoplecostomus sp. 2) and São João river (Neoplecostomus yapo). Cytogenetic data revealed a diploid number of 54 chromosomes to the four populations, few heterochromatic regions and independent chromosome sites for 5S and 18S ribosomal genes. The cytogenetic results revealed a high karyotypic stability, which is also observed for the subfamily Neoplecostominae. Also, were performed molecular analyzes by mitochondrial cytochrome c oxidase subunit 1 gene (COI) amplification, where all genetic distances were higher than 4.7%. In addition, contrary to chromosome stability, genetic distance data also showed absence of gene flow, population structure and suggested a probable Neoplecostomus species not described yet for Pinhão river at Iguaçu basin.