First cytogenetic characterization of Loricaria simillima (Loricariidae, Siluriformes) from Paraná River (Argentina) with emphasis in cytotaxonomy of Loricaria

Abstract

This work aims to establish some cytogenetic characteristics of Loricaria simillima from Paraná River. The obtained results show that L. simillima has a 2n = 64 diploid number, with 12 metacentric, 12 sub-metacentric and 40 sub-telo/acrocentric chromosomes. No chromosomal differences were found between sexes. The nucleolus organizer region (NOR) revealed by Ag-NOR was located next to the centromeric region in the short arm of pair 8. The C-bands were pale and detected in pericentromeric regions of the most chromosomes and interstitially on a sub-metacentric pair, coincident with secondary and NORs constriction. A conspicuous interstitial band on an acrocentric chromosome was also observed. Finally DAPI and CMA3 fluorescent bandings showed G-C richness at the NOR region. Present data evidence a great similarity among L. simillima, L. cataphracta and L. carinata, reinforcing the hypothesis that they constitute a closely related phylogenetic group.