A NEW AREA OF ENDEMISM FOR AMAZONIAN BIRDS IN THE RIO NEGRO BASIN

We describe a new area of endemism for Amazonian birds which we designate as the Jau Area of Endemism. This area of endemism in central-western Amazonia north of the Rio Solimoes was identified through congruent distributions of six avian taxa: Psophia crepitans ochroptera Pelzeln 1857, Nomula amattrocephala Chapman 1921, Pteroglossus azara azura Vieilot 1819, Picumnus lafresnayi pusillus Pinto 1936, Synallaxis nailans confinis Zimmer 1935, and Mynnoborus myotherinus ardesiacus Todd 1927. The southern and eastern limits of this area of endemism are the middle courses of the Solimoes and Negro rivers, respectively. The northern limits apparently coincide with sandy soil vegetation along the middle Rio Negro. The western boundary remains undefined, but could involve the Japura or Ica rivers north of the upper Solimeles. Taxonomic studies and expansion of ornithological collections are needed to more precisely delimit the Jau Area of Endemism. It is possible the avian taxa restricted to the Jail Area of Endemism are derived through parapatric or peripatric speciation events from taxa whose ranges were centered in the Imeri and Napo areas of endemism. Alternatively, tectonic events that affect the lower course of the Rio Negro could influence bird distribution in this region if they serve as vicariance mechanisms. Received 27 June 2007. Accepted 15 July 2011.