Enlarging the knowledge on Graomys griseoflavus (Rodentia: Sigmodontinae) in Patagonia: distribution and environments

UDRIZAR SAUTHIER D.E. ; FORMOSO ANAHÍ E.; TETA PABLO; ULYSES F.J. PARDIÑAS

MAMMALIA

WALTER DE GRUYTER & CO

Lugar: Berlin; Año: 2011 vol. 75 p. 185 - 193

0025-1461

The Leaf-eared mouse Graomys griseoflavus is a medium-sized sigmodontine rodent of the tribe Phyllotini that occurs throughout a wide area of the Chaco and Andean-Patagonic domains, from southcentral Bolivia through western Argentina to central and eastern Santa Cruz province (Yepes 1935, Cabrera 1961, Hershkovitz 1962, Díaz et al. 2006). The southern geographic distribution of G. griseoflavus (i.e., south of 398S) is poorly known, basically restricted to a few records based mainly on owl pellets analyses (Nabte 2003, Pardiñas et al. 2003, 2004, Nabte et al. 2006)and collected specimens (e.g., Daciuk 1974, Monjeau et al.1997, 1998, Rodriguez and Theiler 2007). Here, we review the geographic distribution of G. griseoflavus in Patagonia based on (a) literature records, (b) small mammal trappings carried out during the past ten years, and (c) study of owl pellets. We compiled 188 recording localities of which 141 are new. We extend 94 km southward, 176 km northward and 212 km westward the known distribution for this species. We achieved a better understanding of the geographic distribution of G. griseoflavus from its record in intermediate localities, especially in Central Patagonia (Chubut province) and northeast of Santa Cruz province. In a broad view, G. griseoflavus is almost restricted to the Monte Province. However, its western, northern and southern range extension in Patagonia surpasses the limits of this unit and penetrates into the Patagonic Province along the main watercourses that dissect the region, such as the rivers Negro, Chubut, Chico and Deseado.How these rivers promote the dispersion of this and, probably, other species is actually unknown. We can infer that microclimate mesic conditions, sandy soils and shrub development are significant elements for favoring dispersion. Populations of G. griseoflavus also occur over a narrow strip of territory on the Atlantic coastal sector. In turn, G. griseoflavus does not penetrate into the highlands of central Patagonia, as Somuncurá plateau or the central plateaus of Santa Cruz province (e.g., Gran Altiplanicie Central), where the climatic conditions are perhaps too hostile for this species. This distribution pattern, with insights into the steppe (Patagónica Province) following the courses of major rivers and along coastal areas, has been observed in other species of small mammals primarily linked to the Monte such as Calomys musculinus (Thomas 1913), Akodon iniscatus (Thomas 1919) and Thylamys pallidior (Thomas 1902) (Pardiñas et al. 2003, Pardiñas 2009, Udrizar Sauthier 2009). We can learn from this note that G. griseoflavus is an important component of the rodent diversity in Patagonia occupying a significant portion of this vast territory. As many other small mammal species not typically present in the western portion of this region, G. griseoflavus was, in part, ignored as a Patagonian element. In the past decade, an impressive amount of data from a variety of sources and approaches are contributing to depict a new geography for Patagonian mammals (Lessa et al. 2010). We are confident that in the near future refined databases as presented here for G. griseoflavus will be crucial for a better analyses and understanding of biotic evolution in the Southern Cone of South America.