Euryoryzomys emmonsae
It lives only in a limited area south of the Amazon River in the state of Pará, a distribution that is apparently unique among the muroid rodents of the region.In 1998, Guy Musser, Michael Carleton, Eric Brothers, and Alfred Gardner reviewed the taxonomy of species previously lumped under "Oryzomys capito" (now classified in the genera Hylaeamys, Euryoryzomys, and Transandinomys).[3] The specific name honors Louise H. Emmons, who, among other contributions to Neotropical mammalogy, collected three of the known examples of the species in 1986, including the holotype.[7] In 2000, James Patton, Maria da Silva, and Jay Malcolm reported on mammals collected at the Rio Juruá in western Brazil.In this report, they provided further information on the Oryzomys species reviewed by Musser and colleagues, including sequence data from the mitochondrial cytochrome b gene.[8] In 2006, an extensive morphological and molecular phylogenetic analysis by Marcelo Weksler showed that species then placed in the genus Oryzomys did not form a single, cohesive (monophyletic) group; for example, O. macconnelli, O. lamia (placed under O. russatus by Musser and colleagues) and O. russatus clustered together in a single natural group (clade), but were not closely related to the type species of Oryzomys, the marsh rice rat (O. palustris).[9] Later in 2006, Weksler and colleagues described several new genera to accommodate species previously placed in Oryzomys, among which was Euryoryzomys for the "O. nitidus complex", including O. emmonsae.[16] Musser and colleagues speculated that E. emmonsae may be scansorial, spending time both on the ground and climbing in vegetation, like the similarly long-tailed rice rat Cerradomys subflavus.