We studied abundance and habitat use in two species of Liolaemus (Squamata: Tropiduridae) at a coastal dune site in eastern Argentina before and 7 years after a road was built at the site. Before disturbance, lizards exhibited similar abundances and a wide segregation in microhabitat use. Liolaemus multimaculatus used flat dunes scarcely covered by Spartina ciliata, while Liolaemus gracilis used the grass Panicum racemosum as cover. After disturbance, the mean number of L. multimaculatus detected by month was significantly less than that observed in the predisturbance period, owing to a drastic reduction in S. ciliata microhabitat patches. The mean number of L. gracilis was similar to that seen during the first period. These differences were clearly linked to habitat loss at the site. We concluded that human impact on the habitat structure of foredunes induced changes in the structure of the lizard assemblage, including shifts in the relative abundance of species and the proportional use of their preferred microhabitats.

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Physiological performance in lizards may be affected by climate across latitudinal or altitudinal gradients. In the coastal dune barriers in central‐eastern Argentina, the annual maximum environmental temperature decreases up to 2°C from low to high latitudes, while the mean relative humidity of the air decreases from 50% to 25%. Liolaemus multimaculatus, a lizard in the family Liolaemidae, is restricted to these coastal dunes. We investigated the locomotor performance of the species at 6 different sites distributed throughout its range in these dune barriers. We inquired whether locomotor performance metrics were sensitive to the thermal regime attributable to latitude. The thermal performance breadth increased from 7% to 82% with latitude, due to a decrease in its critical thermal minimum of up to 5°C at higher latitudes. Lizards from high latitude sites showed a thermal optimum, that is, the body temperature at which maximum speed is achieved, up to 4°C lower than that of lizards from the low latitude. At relatively low temperatures, the maximum running speed of high‐latitude individuals was faster than that of low‐latitude ones. Thermal parameters of locomotor performance were labile, decreasing as a function of latitude. These results show populations of L. multimaculatus adjust thermal physiology to cope with local climatic variations. This suggests that thermal sensitivity responds to the magnitude of latitudinal fluctuations in environmental temperature.

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We describe a new species of Liolaemus of the L. alticolor-bibronii group of the subgenus Liolaemus sensu stricto. We studied meristic, morphometric and qualitative pattern characters. Statistical tests were performed in order to evaluate morphological differences among the candidate species and the most closely geographically distributed species. Molecular analyses of Cyt-b mitochondrial gene were performed in order to estimate the position of the new species in relation to other taxa. We also recorded natural history data such as habitat, behavior, reproductive state, diet, and body temperature. Liolaemus absconditus sp. nov. differs from other species of Liolaemus in presenting a distinct combination of morphological character states of lepidosis and color pattern, being phylogenetically close to Liolaemus tandiliensis, Liolaemus gracilis and Liolaemus saxatilis. The new species is a saxicolous and endemic lizard of the Tandilia Mountain Range System of Buenos Aires Province.