Fernando J. Fernández

Enlarging rodent diversity in west-central Argentina: a new species of the genus Holochilus (Cricetidae, Sigmodontinae)

Abstract On the basis of an adult individual collected in 1955 plus 3 mandibles of latest Holocene age, we describe a new living species of the amphibious rat Holochilus (Sigmodontinae, Oryzomyini) from west-central Mendoza Province, Argentina. The new species is characterized by its short tail, broad zygomatic plate with rounded anterior–superior corner, bony palate without excrescences, large mesolophostyle in the upper first molars and complex upper third molar shorter than the second, and lacking the hypoflexus. The morphological traits displayed by this new Holochilus combine features observed in both the H. brasiliensis and H. sciureus groups with others unique among the genus (e.g., absence of hypoflexus). This new species is the southernmost expression of the genus along the western side of its current range, where it appears isolated in the middle part of the Río Atuel. The finding reported here uncovers and highlights unexpected diversity in southern South American arid lands. Resumen En base a un individuo adulto obtenido en 1955 y tres mandíbulas del Holoceno más tardúo se describe una nueva especie viviente de la rata anfibia Holochilus (Sigmodontinae, Oryzomyini) del centro-oeste de la provincia de Mendoza, Argentina. La nueva especie se caracteriza por su cola corta, placa zigomática ancha con el extremo anterodorsal redondeado, paladar óseo sin excrecencias, primeros molares superiores con mesolofostilos bien desarrollados y tercer molar superior complejo sin hipoflexo y más corto que el segundo molar superior. Los rasgos morfológicos que muestra esta nueva especie de Holochilus combinan características observadas en los grupos de especies de H. brasiliensis y H. sciureus como así también otras únicas en el contexto del género (e.g., ausencia de hipoflexo). Esta nueva especie es la expresión más austral del género en la porción occidental de su rango de distribución y parece estar aislada en el cauce medio del río Atuel. El hallazgo reportado aquí destaca una diversidad insospechada en las tierras áridas del sur de América del Sur.

Taphonomy and dispersion of bones scavenged by New World vultures and caracaras in Northwestern Patagonia: implications for the formation of archaeological sites

Scavenger birds can feed on large- to small-sized vertebrates and may contribute in the formation of archaeological sites. To evaluate the modifications and dispersal patterns of bones produced by New World vulture and caracara from Northwestern Patagonia, samples of adult sheep, young sheep, and hare carcasses were offered and subsequently analyzed. New World vultures and caracaras quickly fed on the samples. Taphonomic and bone dispersal patterns suggest two types of accumulations: (1) open-air sites with large and medium-sized vertebrates represented by complete, fractured, scratched, notched, and punctured elements and (2) rock shelter or cave sites dominated by small vertebrates represented by broken, corroded, fractured, and digested elements.

MICROMAMÍFEROS, TAFONOMÍA Y AMBIENTES DURANTE LOS ÚLTIMOS 3.800 AÑOS A.P. EN EL VALLE MEDIO DEL RÍO GRANDE, MENDOZA, ARGENTINA

Desde una perspectiva tafonomica y paleoambiental se estudiaron restos de micromamiferos recuperados de dos sitios arqueologicos que abarcan un periodo temporal desde 3.800 anos a.p. hasta el siglo XX y se ubican en el curso medio del rio Grande, sudoeste de la provincia de Mendoza (Cueva de Luna y Alero Puesto Carrasco). La presencia de marcas de digestion ligera y moderada indica que los micromamiferos fueron depositados por aves strigiformes, posiblemente Tyto alba. Esto contrasta con el modelo de intensificacion de los recursos planteado para los grupos cazadores-recolectores que habitaron el sur de Mendoza hacia el 2.000 a.p. Los conjuntos zooarqueologicos mostraron cierta estabilidad taxonomica, presentando especies patagonicas (p.ej. Lestodelphys halli, Reithrodon auritus y Euneomys chinchilloides) y otras afines al desierto del Monte (p.ej. Galea leucoblephara, Akodon iniscatus y Calomys musculinus), en contraste con las muestras actuales donde principalmente se hallaron especies patagonicas, senalando un paleoambiente mas arido y calido que el actual.

Small mammals (Didelphimorphia, Rodentia and Chiroptera) from Pampean Region, Argentina

We studied small mammal assemblages recovered from owl pellets collected at 11 locations throughout the Argentina’s Pampean Region. We identified 21 species, including two marsupials, one bat, and 18 rodents. From the analysis of this dataset, we could distinguish three main groups of small mammals that currently inhabit the Pampean Region: 1) a group of taxa related to Pampean agroecosystems ( Calomys spp., Akodon azarae , and Oligoryzomys flavescens ); 2) a group of Brazilian species ( Cavia aperea , Oxymycterus rufus , Necromys lasiurus , Necromys obscurus , Holochilus brasiliensis , and Monodelphis dimidiata ); and 3) a group including species from Patagonia, Espinal and Monte phytogeographic provinces ( Microcavia australis , Oligoryzomys longicaudatus , Eligmodontia typus , Graomys griseoflavus , and Akodon molinae ). In addition, we documented the first record of a species of the large-bodied group of Calomys in Buenos Aires province, expanding its distribution ca. 420 km southward.

New data on the endemic cricetid rodent Holochilus lagigliai from central-western Argentina: fossil record and potential distribution

Abstract The recently described cricetid Holochilus lagigliai is a poorly known amphibious rat to this day restricted to its type locality in Mendoza Province, Argentina. Here, we provide and discuss several new late Holocene records enlarging its past distribution to cover the north portion of the province, indicating that this rodent was widespread in a recent past. We also performed a potential distribution analysis pointing to plausible areas of occurrence in neighboring provinces. Holochilus lagigliai seems to be a mammal negatively affected by the growing pressure of humans on wetlands in the context of drylands that characterizes western Argentina.

Noteworthy sigmodontine (Rodentia: Cricetidae) diversity in southern Brazil as an indication of environmental change during the Holocene

ABSTRACT We describe a new sigmodontine fossil sequence ranging from 8,800 ± 40 to 3,730 ± 60 years BP retrieved from the archaeological site RS-S-327:Sangão (Rio Grande do Sul, Brazil). The studied material includes 2,683 craniomandibular remains totalizing about 20 sigmodontine species. The assemblage encompasses a variety of taxa associated to both open and forest environments. Among the former, we recorded species today disappeared in southern Brazil such as the rare ‘giant’ rats Gyldenstolpia and Kunsia, but also the coney rat Reithrodon and the akodontine Necromys obscurus. Conversely, an important assemblage of sylvan species, including the genera Delomys, Oecomys, and Wilfredomys, reflects forested environments. Several of the recorded sigmodontines, such as Deltamys or Nectomys, constitute first mentions for the southern Brazil Quaternary. One of the most remarkable features of the studied sequence is its noteworthy specific richness, probably due to a combination of local environmental heterogeneity in a regional tendency of changing climatic conditions. The evidence of Sangão plus the previously studied samples from Garivaldino and Pilger sites exposes faunal changes during the Holocene in southern Brazil. In this context, the impoverishment of recent sigmodontine assemblages seems a natural result from the progressive disappearance of extensive open environments since Middle Holocene.