A New Area of Endemism for Amazonian Birds in the Rio Negro Basin

Abstract

We describe a new area of endemism for Amazonian birds which we designate as the Jaú Area of Endemism. This area of endemism in central-western Amazonia north of the Rio Solimões was identified through congruent distributions of six avian taxa: Psophia crepitans ochroptera Pelzeln 1857, Nonnula amaurocephala Chapman 1921, Pteroglossus azara azara Vieilot 1819, Picumnus lafresnayi pusillus Pinto 1936, Synallaxis rutilans confinis Zimmer 1935, and Myrmoborus myotherinus ardesiacus Todd 1927. The southern and eastern limits of this area of endemism are the middle courses of the Solimões 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 Japurá or Içá rivers north of the upper Solimões. Taxonomic studies and expansion of ornithological collections are needed to more precisely delimit the Jaú Area of Endemism. It is possible the avian taxa restricted to the Jaú 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.