Body temperature is fundamental for the ecology of ectotherms due to its direct effect on their fitness. The thermoregulation of small reptiles involves a regulatory process that depends on morphophysiological and behavioural adjustments, along with environmental thermal characteristics, to maintain as close as possible to their optimum temperature. In this study, we evaluated the thermoregulation capacity of Phyllodactylus gerrhopygus, a relatively small and crepuscular-nocturnal gecko. Specifically, the aims of the present work were: 1) to determine if this species behaves as a thermoregulator or thermoconformer species, 2) to examine if the preferred body temperatures (Tpref) vary during the hours of potential thermoregulation and 3) if there are differences in daily patterns of Tpref and thermoregulation between juveniles and adults. In the field, we recorded the Tb of geckos and the substrate (Ts) and air (Ta) temperatures from their refuges. In the laboratory, we evaluated Tpref by recording the temperature geckos selected in a thermal gradient at different times of the day. We found a positive association between Tb and Ts. The positive correlation between Tb and refuge temperature suggests that P. gerrhopygus is a thigmothermic and thermoconformer species. Both juveniles and adults select similar temperatures and neither of them thermoregulates. The Tpref was significantly higher during the evening (32.23 ± 5.91 °C) than the morning period (25.2 ± 9.02 °C). We did not find differences between juveniles and adults. Our results are similar to those found in other phylogenetically close lizards, suggesting a strong phylogenetic inertia in thermal preferences.
