Biogeographical analysis of the Rio de la Plata fluvial system wetlands based on climbing and epiphyte plants

Ecological regionalization schemes emphasize the coastal wetlands of the Plata basin as an independent unit, because their characteristics contrast with the areas they cross. In the historical regionalization schemes, based on areas of endemism, there is no consensus to whether the riverine environments are a biogeographic unit, and in the case that they are, to which biogeographic province they belong. The positions about this topic can be summarized as: a) the wetland and forests system belongs to a district within the Parana province; b) belongs to the Pampean province, and c) it is not possible to locate them in terrestrial regionalizations. In order to verify which of the hypotheses is better supported, an exploration for common distribution patterns was made, based on the concept that nestednes of areas of endemism is the essential tool for a regionalization. The geographic distribution of the climbing plants and epiphytes species that reach the Argentine coast of the Rio de la Plata by the fluvial route was studied. Recurrent patterns of geographic distribution of river species were achieved and the location of the system in the biogeographic units recognized in the historical regionalizations was specified. The large number of species restricted to this area allows us to recognize it as an area of endemism nested within the Parana province. This supports the hypothesis that gallery forests can be considered an extension of the Mixed Forests district of the Parana province.