Origin of species diversity in the catfish genus Hypostomus (Siluriformes: Loricariidae) inhabiting the Paraná river basin, with the description of a new species

Abstract

Within the Loricariidae, the genus Hypostomus is one of the most diversified freshwater catfish groups. Using new sequence data from the mitochondrial Control Region (D-loop) we examined the phylogeny of this genus. Our phylogenetic analyses suggest that, in the Paraná river basin, species diversity in the genus Hypostomus has been shaped by two processes: 1) by inter-basin diversification, generating groups of species that inhabit different basins, as a result of dispersal events; and 2) via intra-basin speciation as a result of basin fragmentation due to past marine transgressions, which produced groups of species within a basin. Using the D-loop as a molecular clock, each event of diversification was dated and linked with documented hydrological events or sea level changes. We also assessed the possible dispersal routes between the Paraná and Uruguay rivers, in addition to the obvious dispersal route via the Río de la Plata estuary. Finally, we describe a new species of Hypostomus inhabiting Middle Paraná river, Hypostomus arecuta n. sp. This species can be separated from all other Hypostomus by having light roundish dots on a darker background and by number of premaxillary/ dentary teeth.