Phylogeographic patterns in suckermouth catfish Hypostomus ancistroides (Loricariidae): dispersion, vicariance and species complexity across a Neotropical biogeographic region.

The upper Paraná River system (UP) is a highly diverse biogeographic province for freshwater fishes, but little is known about processes which shaped that diversity. This study describes the phylogeographic pattern in Hypostomus ancistroides, a suckermouth catfish species that is widespread in the UP and also reported from the adjoining Ribeira do Iguape basin. We used complete mtDNA sequences of ATPase 6/8 of 162 specimens to infer haplotype distribution using phylogenetic and demographic analyses and a Bayesian molecular clock. Results suggest that during the Quaternary H. ancistroides has undergone superimposed phylogeographic histories, alternating between isolation and subsequent merging of different populations. Occurrence of an isolated population on the Ribeira de Iguape is demonstrated to be a Pleistocene headwater capture event. Widely distributed haplotypes indicate deep genetic differences and suggest that populations of H. ancistroides were isolated for considerable time, but did not undergo speciation because of recurrent population mixing.