ORIGINAL INVESTIGATION A new species of Philander Brisson, 1762 (Didelphimorphia, Didelphidae) David A. Flores à , Rube´n Marcos Barquez, Marı´a Mo´nica Dı´az PIDBA (Programa de Investigaciones de Biodiversidad Argentina), Facultad de Ciencias Naturales, Universidad Nacional de Tucuma´n, Miguel Lillo 205, CP 4000, Tucuma´n, Argentina CONICET (Consejo Nacional de Investigaciones Cientı´ficas y Te´cnicas), Argentina Received 20 September 2006; accepted 20 April 2007 Abstract A new species of Philander, known from two localities in Bolivia and one in Peru, is described. The new species is externally similar to sympatric populations of P. opossum, but both have several differences, such as ventral pelage color, nasal morphology, condition of the zygomatic arches, and rostral tympanic process of the petrosal. Morphometric differences with other taxa in the genus are also shown. Based on the few localities known at present, it is probable that the new taxon has a wide geographic range in Amazonian forest. The description of another species of Philander reflects the complexity of the genus, and the fact that the holotype corresponds to a museum specimen demonstrates one more time the importance of the study of the systematic collections. We describe external, dental, and cranial morphology, and we offer morphometric data as well as comparisons with other species in the genus. r 2007 Deutsche Gesellschaft fu¨r Sa¨ugetierkunde. Published by Elsevier GmbH. All rights reserved. Keywords: Philander; Bolivia; Peru; Systematics; Taxonomy Introduction The genus Philander Brisson, 1762 includes several species commonly known as four-eyed opossums, owing to the presence of a pale spot above each eye. It has a wide distribution in the Neotropics, being known from Tamaulipas, Mexico, and south to northern Argentina (Hershkovitz 1997). The extant forms of Philander were included within the subgenus Metachirus (genus Didel- phys) by Thomas (1888). For decades, the nomenclator- ial status of the genus was discussed by several authors (e.g. Hershkovitz 1949, 1976, 1981, 1997; Husson 1978; Pine 1973; Gardner 1981). Simpson (1972) and Pine (1973) suggested that Philander should be treated as a subgenus of Didelphis, but Reig et al. (1987) showed that the group was clearly distinctive in a diverse array of anatomical traits. To date, the species included in the genus, and their distributions, remain uncertain in several taxonomic and distributional aspects (see Patton and da Silva 1997; Lew et al. 2006). Traditionally, Philander was considered to be a monotypic genus, containing only P. opossum and several synonyms (Cabrera 1958), among them P. andersoni (Osgood, 1913), P. mcilhennyi (Gardner and Patton, 1972), and P. frenatus (Olfers, 1818). Emmons and Feer (1990) and Gardner (1993) considered Philander andersoni to be a valid species and included P. mcilhennyi as a junior synonym. Hershkovitz (1997) reviewed the genus adding to the analysis several morphological traits such as cranio- dental and soft anatomy, as well as distribution and behavior, and recognizing only two species: P. opossum ARTICLE IN PRESS www.elsevier.de/mambio 1616-5047/$ - see front matter r 2007 Deutsche Gesellschaft fu¨r Sa¨ugetierkunde. Published by Elsevier GmbH. All rights reserved. doi:10.1016/j.mambio.2007.04.002 Mamm. biol. 73 (2008) 14–24 à Corresponding author. PIDBA (Programa de Investigaciones de Biodiversidad Argentina), Facultad de Ciencias Naturales, Universi- dad Nacional de Tucuma´n, Miguel Lillo 205, CP 4000, Tucuma´n, Argentina. E-mail address: davflor@gmail.com (D.A. Flores).