Valeria Corbalán

Mammals of the Monte Desert: from regional to local assemblages

Abstract Much of South America consists of diverse arid and semiarid regions characterized by high mammal endemism as a result of a complex interplay between place and lineage histories. In this review we summarize and highlight several biogeographical and ecological features of the small mammals of South America drylands, with special focus on the Monte Desert biome. We provide information on population characteristics, community structure, food and habitat use, and responses to disturbances. Major findings at different scales include the distinctiveness and high species turnover across South American drylands and Monte Desert ecoregions; synchronous population fluctuations with high variability between years; herbivory and omnivory as dominant trophic strategies; community structure organized through habitat and food segregation; and the importance of a landscape mosaic of grazed and ungrazed areas for maintenance of small and medium-sized mammal diversity.

Basking behaviour in two sympatric herbivorous lizards (Liolaemidae: Phymaturus) from the Payunia volcanic region of Argentina

We studied several aspects of the thermal biology of two coexisting saxicolous species of the genus Phymaturus (Liolaemidae) at the Payunia, a volcanic region in Argentina where harsh conditions prevail. We marked individuals in grids and assessed the environmental conditions when the individuals showed their maximum activity (i.e. when more than 50% of marked individuals were active), the time spent basking, and the postural behaviour in relation to different cloudiness conditions. We found that temperatures recorded when the species exhibit their peaks of activity were higher for Phymaturus payuniae, the smaller species, during the summer at one of the three studied sites. Phymaturus roigorum exhibited the longest basking periods, but during these longer periods cloudy conditions prevailed. Both species adopted a head-up posture when conditions were sunny and a head-down posture when under cloudy conditions. This is the first contribution where thermal aspects of two sympatric species of Phymaturus are evaluated.

Prolonged larval development in the Critically Endangered Pehuenche’s frog Alsodes pehuenche: implications for conservation

Overwintering is an anuran strategy to survive in cold-temperate climates. Those aquatic species that withstand harsh conditions and short growing seasons are candidates for having long larval periods. Prolonged larval development, which includes overwintering for more than two years, has been reported for North-American and Euro-Asiatic species, but this strategy has been poorly studied in the Southern Hemisphere. Alsodes pehuenche is an endemic frog from the high Andes mountains of Argentina and Chile, recently categorized as Endangered by the Asociacion Herpetologica Argentina (AHA) and as Critically Endangered by the International Union for Conservation of Nature (IUCN). We studied egg laying in this species and its larval development by marking tadpoles with elastomers. We found that eggs are laid in clumps at the beginning of summer. The larval cycle includes four winters, although a fifth winter should not be ruled out. This is the first study that demonstrates a long larval development (four winters) in South-American species and has important implications for conservation biology.

DNA Barcoding of Phymaturus Lizards Reveals Conflicts in Species Delimitation within the patagonicus Clade

Abstract Under the DNA Barcode initiative, we used the mitochondrial locus cytochrome c oxidase I to test if this molecular marker would reliably distinguish among lizard species of the patagonicus clade of Phymaturus. Using 18 described species and two populations of unidentified species, we calculated intra- and interpopulation genetic distances for all operational taxonomic units and performed phylogenetic reconstructions using maximum parsimony and maximum likelihood. We identified different species that share the same barcode index number (BIN). We recorded only 12 of the 18 previously described species and one candidate species from the new population. By comparing our results with published morphological and molecular phylogenies, as well as with previous debates, we propose possible explanations for this. In some cases (such as the group with the same BIN formed by Phymaturus spurcus, Phymaturus spectabilis, Phymaturus excelsus, and Phymaturus agilis), where other authors debated the identity of the species, we suggest that the low genetic distances could be attributable to the presence of one species with high polymorphism. On the other hand, in geographically isolated species such as the group formed by Phymaturus payuniae and Phymaturus nevadoi, the group formed by Phymaturus somuncurensis and Phymaturus ceii, and the group formed by Phymaturus indistinctus and Phymaturus videlai, the topology of the phylogenetic trees indicates that the low genetic distances (also found by other authors analyzing cytochrome b) could be attributable to shared ancestral polymorphism resulting from incomplete lineage sorting.

First record of the American bullfrog Lithobates catesbeianus (Shaw, 1802) in Mendoza province, Argentina

We discovered a well established populationof L. catesbeianus in Mendoza province, San Carlosdepartment, Capiz locality (33° 41’ 11’’S, 68° 59’09’’ W; elevation: 920 m) and other nearby localitiesat Tunuyan department. Thisrecord extends the distribution range of this species270 km S-SE from Calingasta, San Juan, and 400km W-SW from Villa Dolores, Cordoba. The regionis part of the Monte phytogeographic province,which is characterized by an arid climate with meanannual temperature of 17.7oC (mean annualminimum and maximum: -1.4 and 38.0oC,respectively) and mean annual rainfall of 331.2 mm,which occurs mainly in summer.