Journal of Mammalogy, 97(4):1177–1196, 2016 DOI:10.1093/jmammal/gyw070 Published online May 5, 2016 Version of Record, first published online May 05, 2016, with fixed content and layout in compliance with Art. 8.1.3.2 ICZN. A new species of arboreal rat, genus Oecomys (Rodentia, Cricetidae) from Chaco ULYSES F. J. PARDIÑAS,* PABLO TETA, JORGE SALAZAR-BRAVO, PHIL MYERS, AND CARLOS A. GALLIARI Instituto de Diversidad y Evolución Austral (IDEAus-CONICET), Casilla de Correo 128, 9120 Puerto Madryn, Chubut, Argentina (UFJP) División Mastozoología, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Avenida Ángel Gallardo 470, Downloaded from https://academic.oup.com/jmammal/article-abstract/97/4/1177/1753501 by guest on 29 October 2019 C1405DJR Buenos Aires, Argentina (PT) Department of Biological Sciences, Texas Tech University, 2901 Main st., Lubbock, TX 79409-3131, USA (JS-B) Museum of Zoology, 1109 Geddes, University of Michigan, Ann Arbor, MI 48109, USA (PM) Centro de Estudios Parasitológicos y de Vectores (CEPAVE), Calle 120 entre 61 y 62, 1900 La Plata, Buenos Aires, Argentina (CAG) * Correspondent:
[email protected] A new species of rodent is added to the highly diverse genus Oecomys (Cricetidae, Sigmodontinae, Oryzomyini) based on specimens collected in the Argentinian provinces of Chaco and Formosa. The new species is characterized by a derived carotid circulatory pattern, a feature shared with O. concolor, O. mamorae, and O. sydandersoni. A unique combination of morphological, morphometric, and molecular characters, however, provides unambiguous evidence of its validity as a separate entity. Individuals of the new species are larger than other representatives of Oecomys, and their skulls have wide and cuneate interorbital regions with well-developed supraorbital shelves, long incisive foramina, long palates, absent alisphenoid struts, and broad Eustachian tubes.