Dense-sampling reveals a complex distributional pattern between the southernmost marsupials Lestodelphys and Thylamys in Patagonia, Argentina

FORMOSO, A.E.; UDRIZAR SAUTHIER, D. E.; TETA, P.; PARDIÑAS, U.F.J.

MAMMALIA

WALTER DE GRUYTER & CO

Año: 2011 vol. 75

0025-1461

Lestodelphys halli and Thylamys pallidior are southernmost representatives of the Order Didelphimorphia. We analyzed their southern distribution compiling locality records south of 42°S (Chubut and Santa Cruz provinces). We found 87 locality records for L. halli and 105 for T. pallidior. The distribution of L. halli reaches the central plateaus of Santa Cruz province but avoids the northeastern corner of the Deseado Massif and its type locality is marginal to its current geographic range. We report the southernmost location for this species. The eastern and southern distribution of T. pallidior follows the courses of major rivers and coastal areas and it was not found at altitudes greater than 700 meters. Its southern distribution is much more reduced than in L. halli, not reaching latitudes south of 46° S. We have recorded 20 localities of sympatry (all of them from owl pellet samples) but we have not found conclusive evidence of syntopy by trapping at any site, because of that we suspect that the observed sympatry is due to foraging activity of the involved raptors. Both marsupials have widespread distribution in south-central Patagonia with two distributional, ecological, and probably biogeographic histories.