Notes on the behavior of Tropidurus melanopleurus Boulenger (Reptilia, Sauria, Iguanidae)

Abstract

SUMMARY Field observations on a population of Tropidurus melanopleurus confinn conspecificity by detection of courtship behavior. Peculiarities in female and juvenile behavior were observed in this poor known species.Overall observations were conducted on a population of Tropidurus melanopleurus from Aguas Blancas (Salta, Argentina) near the frontier with Bolivia, on the south bank of the Bermejo river.The observed population inhabits areas that are lacking in vegetation almost completely. The lizards are either found on vertical walls made of tertiary sedimentary rocks, which were exposed by the construction of a road, or on the sandy shore of the river, which probably 90rresponds to its original biotope.The population of this region has been described as two species, T. pictus and T. praeomatus, which can be differentiated by their morphology and coloration (Muller, 1924). Peters and Donoso·Barros (1970). placed both in the synonymy of T melanopleurus, Boulenger. Laurent (1980) describes the sexual dichromatism for specimens of this species collected in the National Park of Baritu (Salta, Argentina), area to which the observed population.belongs. The first indication of conspecificity of T pictus and T. praeomatus as suggested by Laurent, came from observation of their courtship behavior. This was confirmed by our observations. These were conducted during a collection trip in January 1989 , between 1050 and 1250 hours. We were able to record behavioral patterns of adults as well as of juveniles.With respect to adults, extensive activity was observed among females and males , both performing pushups. During observation we followed, on a rock at two meters above the ground, a female repelled three other females which were attempting to reach her. In one instance , there was physical contact between two females, the first jumping on the invading female which then escaped and was purshued a short distance . The "territorial" female then chased for short distances the other two females which appeared to be trying to reach a rock on which an adult male was perched , and in front of which she had been performing several pushups . The male twisted over the rock and intermutlantly licked it . At one pOint , the female chansed the male . He withdrew a little but later again approached the female which arched her back, and with stiff legs and tail, departed. We did not observe copulation . Pursuits and escapes were observed in various groups of females, these being much more numerous than the males (approximately 10 to 2). In some species females may exhibit territorial defense behavior (Carpen-I. Instituto de Herpetolog{a, Fundacion Miguel Lillo .Miguel Lillo 25 1, 4000 Tucuman, Argen tina.