BIOGEOGRAPHY OF THE FRESHWATER DECAPODS IN THE LA PLATA BASIN, SOUTH AMERICA

COLLINS PABLO AGUSTIN; GIRI FEDERICO; WILLINER VERONICA

JOURNAL OF CRUSTACEAN BIOLOGY

CRUSTACEAN SOC

Lugar: Kansas; Año: 2010

0278-0372

The distributions of freshwater fauna in the La Plata Basin, including decapods, are dynamic; their actual distributions depend on notonly their movements but also on environmental fluctuations. The La Plata system has a diverse range of environments, which arecolonized by crustaceans with complex evolutionary histories. Our aim was to elucidate the distribution patterns and relationships ofcurrent freshwater decapod fauna in terms of the different geo-climatic processes at work in the La Plata system. We recognized 13zones based on their unique environmental characteristics. Species lists were assembled through field samples, examination of museumcollections, and literature analysis. Faunistic similarity was evaluated using the Jaccard index and cluster analysis. A parsimony analysisof endemicity (PAE) was applied to determine the most parsimonious of all possible tree topologies. There were 69 species freshwaterdecapods analyzed in the La Plata Basin. The Mata Atla´ntica (MA), Parana´ Superior (PS), and Uruguay Superior (US) zones aredistinguished by their high species richness values, whereas the western and southern basin regions exhibit the lowest species richnessvalues. The Paraguay-Pantanal (PP) and Paraguay-Pilcomayo-Bermejo (PPB) zones share some prawn taxa with the Amazon Basin. Theeastern zones of the La Plata Basin were grouped by the presence of several species of the genera Parastacus, Aegla, and Trichodactylus.The northern, central, and western zones were characterized by species of the genera Dilocarcinus, Sylviocarcinus, and Zilchiopsis.According to the PAE analysis, two major zones were recognized in relation to the presence of freshwater decapods (eastern andwestern-central zones). In the western-central zones, three sub-areas were identified; one shares species with the Amazon basin theothers have a relationship with the eastern and northern regions and represents a region that is strongly influenced by a temperate climateand therefore possesses diminished species richness values.