Comparative thermal ecophysiology in Pristidactylus scapulatus populations from the Puna region of Argentina.

Reptiles are important models for understanding fundamental aspects of physiological ecology and for assessing how environmental change can impact biodiversity. Abiotic factors (micro-environmental temperatures, operative temperatures, thermal quality) may vary geographically along an altitudinal and latitudinal gradient, and therefore the different thermal resources available for thermoregulation also vary. Comparative analyses among populations provide an opportunity to understand how variation in abiotic factors can affect different ecophysiological traits of a species at different geographical points. Our objective was to carry out a comparative study between two populations of Pristidactylus scapulatus in the Puna region of Argentina, providing the first data available on thermal ecophysiology, thermoregulatory efficiency and locomotor performance of the species. We determined field body temperature, micro-environmental temperatures and operative temperatures. In the laboratory, we measured preferred temperatures and calculated the index of thermoregulatory efficiency. In addition, we recorded critical temperature (minimum and maximum) and we estimated the thermal sensitivity of locomotion by measuring sprint speed at different body temperatures; based on these data we calculated the optimal temperature for performance, the optimal performance breadth and thermal safety margin. Air temperatures and operative temperatures were different between sites. However, we only found differences between populations in the minimum critical temperatures, with these being lower at higher latitude. We note that P. scapulatus populations adjust optimal temperatures of performance to field body temperatures and preferred temperatures, which could reduce the costs of thermoregulation in lizards with limited daily activity and who inhabit sites with variable and unpredictable environment temperatures. We conclude that Pristidactylus scapulatus has thermal sensitivity in locomotor performance, is a moderate thermoregulator with respect to the environment and is a eurithermic lizard, which has thermal flexibility in the cold.

New association between Amblyomma parvitarsum (Acari: Ixodidae) and the endemic lizard Liolaemus eleodori (Iguania: Liolaemidae) in Argentina

Records of lizard parasitizing ticks in Argentina are scarce and incomplete. We recorded a new population of Liolaemus eleodori, a lizard endemic to Argentina, parasitized by the hard tick Amblyomma parvitarsum. Hence, the objective of this study is to report this new association and enhance knowledge about its parasitism on reptiles of Argentina. To do this, we researched ectoparasitic loads. We determined different ecological predictors: intensity, mean intensity and prevalence. Our results provide the first data on the parasitism of nymphal stages on this lizard. We found a tick prevalence of 91.6% and a mean intensity of 2.45. Considering sexes, mean intensity was higher in females than in males. The gular region and lower ventral abdomen were the highest parasitized anatomical regions. This new record of the host-parasite association suggests that this relationship is not accidental, with this lizard species being central to the tick's life cycle. Probably, the microhabitat of this lizard species is essential for the tick to reach high prevalence. Our study represents an important contribution and provides additional information on parasitism in lizards of Argentina.