Integrative taxonomy, systematics and distribution of the genus Eligmodontia (Rodentia, Cricetidae, Sigmodontinae) in the temperate Monte Desert of Argentina

Abstract

The systematics and distribution of South American sigmodontine rodents a matter of continuous revision and debate. The silky mice, genus Eligmodontia Cuvier, 1837, are among the most specialized murid rodents endemic to South America and its diversification for desert existence is associated with the uplift of the Andes and the early development of arid landscapes. Aiming to clarify the systematics of the species of silky mice occurring in the driest portion of the temperate Monte Desert in Argentina, qualitative and quantitative external and cranial characters, cytogenetics and molecular relationships, were studied. We characterized three karyotypes of Eligmodontia; two of which are described for the first time, and allocated them to previously named species. E. moreni Thomas, 1896 (2n=52 and FN=50), E. typus Cuvier, 1837 (2n=44 and FN=44) and E. marica Thomas, 1918. The later shows the same diploid number of E. typus, but its Xchromosome is not METACENTRIC but ACROCENTRIC . A discriminant analysis of external and cranial data separates E. moreni from E. typus and E. marica. Whereas these last ones show some degree of overlap. The morphological and chromosomal differentiation of Eligmodontia is sustained by DNA distances. Phylogenetic analyses show two major clades. One formed by E. moreni, E. puerulus and E. hirtipes, sharing a high FN and a northern distribution, and THE other formed by E. typus, E. marica and E. morgani with low FN and a central-southern distribution. Two centers of diversification are proposed to explain the evolution of Eligmodontia.

The mammals of the Monte Desert revisited

“…Just an example, other than the Monte, is the long-term ecological program carried on in the semiarid North of Chile, where we have gained an in-depth comprehension of particular processes and dynamics in relation to ''El Niñ o'' event and its impact on vertebrate assemblages and rodent outbreaks among others (Jaksic et al, 1997;Lima et al, 1999;Marquet et al, 1998;Meserve et al, 2003, and references). (2004), Diaz et al (2000), Giannoni et al (1996), Kufner and Chambouleyron (1991), Lanzone et al (2007), Mares and Ojeda (1982), Ojeda (1989), Ojeda et al (1999), Rosi et al (2002), Taraborelli et al (2003), and Tognelli et al (1995Tognelli et al ( , 1999.…”

“…In most cases these lists were based on records from few localities of the north and central Monte, as well as earlier published information. The description of new mammal taxa in recent years Mares, 1995, 2002;Braun et al, 2000;Lanzone et al, 2007;Mares et al, 2000), has reverted previous generalizations of a depauperate mammal fauna (Mares, 1975). The Monte Desert over its total geographical range now accounts for approximately 73 mammal species (Table 1) and possesses a relatively high endemicity in comparison with other arid and semiarid biomes (Ojeda et al, 2002).…”

Diversidad y endemismo de los mamíferos del Perú

“…(Thomas, 1902) Musser y Carleton (2005) (Spotorno et al 2001). Ambos taxa son también diferenciados en las secuencias del gen de citocromo-b (Lanzone et al 2007, Mares et al 2008. Más temprano, Pearson y Eremoryzomys polius (Osgood, 1913) Especie endémica del departamento Amazonas, al este del río Marañón.…”

Habitat selection by two sympatric rodent species in the Monte desert, Argentina. First data for Eligmodontia moreni and Octomys mimax

“…We studied habitat selection in one species of Octodontidae (Vizcacha Rat O. mimax; weight: 120.0 AE 2.0 g, Ebensperger et al, 2008) and two species of Cricetidae (silky mouse or Monte gerbil mouse E. moreni (weight: 17.6 AE 3.3 g, Lanzone et al, 2007) and gray leaf-eared mouse G. griseoflavus), although eventually only the first two were captured in sufficient numbers. Several individuals of a marsupial, Thylamys pusillus, were also captured but not enough to include them in the analyses.…”