Lagostomus telenkechanum , sp. nov., a new lagostomine rodent (Caviomorpha, Chinchillidae) from the Arroyo Chasicó Formation (late Miocene; Buenos Aires Province, Argentina).

We describe a new lagostomine rodent (Caviomorpha, Chinchillidae),Lagostomus telenkechanum, sp. nov., from the Arroyo Chasicó Formation (late Miocene; Buenos Aires Province, Argentina). Three characters permit its assignment toLagostomus: suborbital canal for the infraorbital nerve limited by a bony lamina, well-developed posterior process of the palatine, and posterior maxillary foramen located at the midpoint of the M3. In addition, we identify the new species based on a unique character combination (e.g., small size, palatines reaching anterior to the level of the midpoint of P4, anterior margin of mesopterygoid fossa at the level of the anterior border of M3, upper cheek teeth more compressed anteroposteriorly and more obliquely implanted in the maxilla than inL. pretrichodactyla, L. compressidens, andL. maximusbut less than inL. incisus, and thick cement layer in the hypoflexus). Because the early Miocene–middle Miocene genera,ProlagostomusandPliolagostomus, are no longer recorded from the late Miocene, whereas the oldest record of the extant genusLagostomusis recognized at that time, we consider this period as an important turnover time in the taxonomic composition of the Chinchillidae. This study increases understanding of the taxonomic diversity of the late Cenozoic lagostomines, contributing to the knowledge of the evolutionary and paleobiogeographic history of chinchillids. http://zoobank.org/urn:lsid:zoobank.org:pub:36EF6949-4226-492C-90A6-C51658852AD7 SUPPLEMENTAL DATA—Supplemental materials are available for this article for free atwww.tandfonline.com/UJVP Citation for this article: Rasia, L. L., and A. M. Candela. 2016.Lagostomus telenkechanum, sp. nov., a new lagostomine rodent (Caviomorpha, Chinchillidae) from the Arroyo Chasicó Formation (late Miocene; Buenos Aires Province, Argentina). Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1239205. [ABSTRACT FROM AUTHOR]