A hint on the unknown diversity of eastern Andes: high endemicity and new species of mammals revealed through DNA barcoding

The eastern Andean slopes harbours a diverse fauna with multiple endemic and endangered species. The region is identified as a biodiversity hotspot with high conservation priority. However, it remains one of the least studied in South America regarding the diversity of mammals. Here we present new data on the diversity of non-volant small mammals (marsupials and rodents) from Parque Nacional del Rio Abiseo (PNRA), a poorly known, remote site located in the eastern Andean slopes in central-northern Peru. We sequenced the mitochondrial gene cytochrome b to provide identification of the collected specimens, and to discuss zoogeographic patterns of the species from PNRA and closely related taxa. In 15 days of sampling at PRNA we registered 16 species (12 rodents, 4 marsupials) on montane forests between 2500 and 2800 m above sea level (asl). Combined with results from previous surveys, the diversity of non-volant small mammals at PNRA (23 species) is the highest ever recorded for high Andes. Remarkably, only four of the 16 species recorded in our expedition could be assigned to described species based on molecular identification. The remaining 12 species need urgent taxonomic attention, several of which are potentially new to science. Moreover, 11 of the 16 species (69%) registered are currently unknown from other sites, suggesting a large beta diversity. A combination of exceptional levels of endemism in Andean montane forests and an obvious sampling bias resultant of the lack of comprehensive surveys explain the high number of 'unique' species at PNRA. Our phylogenetic analyses suggest that the non-volant small mammals from PNRA seem to have diverse phylogeographic affinities, with a closer proximity with central Andes. The scarcity of sequenced samples for comparative analyses from multiple Andean sites is, however, a major barrier to the development of accurate historical reconstructions for these endemic faunas.