Thermal tolerance in the Andean toad Rhinella spinulosa (Anura: Bufonidae) at three sites located along a latitudinal gradient in Chile.

Rhinella spinulosa is one of the anuran species with the greatest presence in Chile. This species mainly inhabits mountain habitats and is distributed latitudinally along the western slope of the Andes Range. These habitats undergo great temperature fluctuations, exerting pressure on the amphibian. To identify the physiological strategies and thermal behavior of this species, we analyzed the temperature variables CTmin, CTmax, TTR, τheat, and τcool in individuals of three sites from a latitudinal gradient (22°S to 37°S). The amphibians were acclimated to 10°C and 20°C and fed ad libitum. The results indicate that the species has a high thermal tolerance range, with a mean of 38.14±1.34°C, a critical thermal maxima of 34.6-41.4°C, and a critical thermal minima of 2.6-0.8°C, classifying the species as eurythermic. Furthermore, there were significant differences in CTmáx and TTR only in the northern site. The differences in thermal time constants between sites are due to the effects of size and body mass. For example, those from the central site had larger size and greater thermal inertia; therefore, they warmed and cooled in a slower manner. The wide thermal limits determined in R. spinulosa confirm that it is a thermo-generalist species, a characteristic that allows the species to survive in adverse microclimatic conditions. The level of plasticity in critical temperatures seems ecologically relevant and supports the acclimatization of thermal limits as an important factor for ectothermic animals to adapt to climate change.

BODY DISTRIBUTION OF HANNEMANIA SP. (ACARI: LEEUWENHOEKIIDAE) IN RHINELLA SPINULOSA, PLEURODEMA BUFONINA, AND PLEURODEMA THAUL FROM CHILE.

Hannemania larvae are parasites of amphibians in North and South America. In Chile, only one species of Hannemania has been reported from Batrachyla taeniata (banded wood frog). The objective of the study was to determine the abundance and body distribution of Hannemania among three amphibians from Antuco (Biobío Region, Chile): Pleurodema thaul (13 adults; Chile four-eyed frog), Pleurodema bufonina (5 adults; large four-eyed frog), and Rhinella spinulosa (15 adults and 16 juveniles; warty toad). Amphibians (82.75 %; n = 49) were infested with Hannemania. The infestation rate in R. spinulosa juveniles was lower than in adults (68 versus 100%, respectively; mean larval intensity: juvenile = 3.2 ± 2.5 and adult = 17.3 ± 16.3). Mean intensity of larval infestation in P. bufonina (63.2 ± 47.9) was higher than in the other two species of amphibians (R. spinulosa adult: 17.3 ± 16.3; R. spinulosa juvenile: 3.2 ± 2.5; P. thaul: 11.62 ± 7.8). There was no significant association between body size and mean intensity of infestation. The inguinal region, ventrum, and dorsal forearm region were the most parasitized. These body zones would be in direct contact with the substrate making the infestation easier for the larvae. This study represents the first record of Hannemania sp. in P. bufonina, R. spinulosa, and P. thaul in Chile.