Anahí E. Formoso

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

Abstract 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. We report the southernmost locality 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 >700 m. Its southern distribution is more reduced than in L. halli, not reaching latitudes south of 46°S. We have recorded 20 localities of sympatry between both taxa, all of them from owl pellet samples; however, we have not found conclusive evidence of syntopy by trapping at any site. Both marsupials have widespread distribution in south-central Patagonia with two different histories: one, that of L. halli, related to Patagonian steppes and the other one linked to arid and semiarid lowlands represented by T. pallidior.

Mammalia, Rodentia, Sigmodontinae, Holochilus brasiliensis (Desmarest, 1819): distribution extention

We report the southernmost record for the marsh rats Holochilus brasiliensis 20 km S of Pedro Luro on Hwy 3, province of Buenos Aires, Argentina (39°41’31.13”S, 62°40’23.5”W) extending the range of the species ca. 110 km S. This represents the first contemporaneous record of H. brasiliensis in Patagonia, and also the only species of sigmodontine rodent with amphibious habits reported in Patagonia.

Bats at the end of the world: new distributional data and fossil records from Patagonia, Argentina

Abstract We report new recent and fossil records in Patagonia for six and three bat species, respectively. These findings significantly increase the previously known number of localities for these mammals in this entire region, filling gaps between previous references for some species (e.g., Histiotus macrotus) and/or extending by 140–350 km the range of others (e.g., Myotis chiloensis, M. levis, Lasiurus varius). In addition, we report for the second time the vespertilionid bat Lasiurus blossevillii in Patagonia. Fossils are mostly restricted to the Late Holocene epoch, and the recorded assemblages are similar to the recent ones. A preliminary analysis of richness indicates that bat diversity south of the Colorado River (around 39°S) decreases from five to six species in the northwestern to one species in the southeastern, changing abruptly around 43°S–46°S. Compared with similar latitudes of the Northern Hemisphere, bat diversity in the Neotropics follows a similar pattern, with <20 taxa occurring south of 35°S.

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

No abstract available

Regional Extinctions and Quaternary Shifts in the Geographic Range of Lestodelphys halli, the Southernmost Living Marsupial: Clues for Its Conservation

The Patagonian opossum (Lestodelphys halli), the southernmost living marsupial, inhabits dry and open environments, mainly in the Patagonian steppe (between ~32°S and ~49°S). Its rich fossil record shows its occurrence further north in Central Argentina during the Quaternary. The paleoenvironmental meaning of the past distribution of L. halli has been mostly addressed in a subjective framework without an explicit connection with the climatic “space” currently occupied by this animal. Here, we assessed the potential distribution of this species and the changes occurred in its geographic range during late Pleistocene-Holocene times and linked the results obtained with conservation issues. To this end, we generated three potential distribution models with fossil records and three with current ones, using MaxEnt software. These models showed a decrease in the suitable habitat conditions for the species, highlighting a range shift from Central-Eastern to South-Western Argentina. Our results support that the presence of L. halli in the Pampean region during the Pleistocene-Holocene can be related to precipitation and temperature variables and that its current presence in Patagonia is more related to temperature and dominant soils. The models obtained suggest that the species has been experiencing a reduction in its geographic range since the middle Holocene, a process that is in accordance with a general increase in moisture and temperature in Central Argentina. Considering the findings of our work and the future scenario of global warming projected for Patagonia, we might expect a harsh impact on the distribution range of this opossum in the near future.

Dense sampling provides a reevaluation of the southern geographic distribution of the cavies Galea and Microcavia (Rodentia)

Abstract The southern distribution of the small cavies Galea leucoblephara and Microcavia australis is reviewed. It has been enriched through the addition of 36 new locality records for G. leucoblephara and 176 for M. australis. Both caviomorph rodents are widespread in Patagonia – the former occurs in the northern portion of the territory, whereas the latter is recorded up to the Strait of Magellan. The reference of Patagonian Galea populations to leucoblephara is still subject to confirmation. Therefore, the status of negrensis must be addressed in future studies. For southern Microcavia australis populations, a rich subspecifical scenario is proposed, including the names australis, kingii, and nigriana. The alpha taxonomy of this cavy needs a fresh approach that is based on a larger sample set coupled with the analysis of molecular markers.

Range extension of Tympanoctomys barrerae (Lawrence, 1941) (Rodentia: Octodontidae) in Patagonia and southernmost record

We report the southernmost record for the octodontid rodent T. barrerae , which is also the second recording locality for this species in Patagonia. The new locality is placed in S Neuquen province, extending the known range of the species about 150 km SW from the nearest previous record. Although T. barrerae is considered a highly specialized rodent of salar flats in Monte desert, the record reported here came from an arbustive rocky environment belonging to the Monte- Patagonia ecotone.