Biogeographic patterns of the freshwater fishes from the state of Espírito Santo, eastern Brazil

Biogeographic studies offer valuable insights into the origin, distribution and extinction of biodiversity. As such, this study aims to identify patterns of diversity and distribution of freshwater ichthyofauna in the state of Espírito Santo, to delineate biogeographic units and to propose a hypothesis of area relationship. A database containing information on 123 fish species occurrences was compiled to conduct analyses of species richness interpolation, bioregionalization, sampling effort interpolation, endemism, and a parsimony analysis of endemism. The sampling effort in Espírito Santo is uneven, with higher representativeness of sampling sites in the highlands. Six freshwater ichthyofauna bioregions were identified, along with three major areas of increased species richness, two consensus areas of endemism and three groups of basins. The central basins of the state are characterized by a marked presence of endemic species. The southern basins also stand out as an area of endemism and density of species typical of mountainous environments, such as loricariids; they are also characterized by a significant faunal overlap with the Rio Paraíba do Sul basin. The results of this biogeographic evaluation reinforce the perception that the watersheds of the state of Espírito Santo have a diverse and characteristic freshwater fish fauna, with well-defined biogeographic units.