Ectoparasitismo em uma população de Tropidurus catalanensis (Gudynas & Skuk, 1983) (Squamata: Tropiduridae) do município de Alegrete, RS

Abstract

Tropidurus catalanensis (Gudynas & Skuk, 1983) is a saxicolous and heliophilous species and its geographic distribution includes the northwest of Uruguay, the northeast of Argentina, the south of Paraguay and the southwest of Brazil, extending to the extreme southwest of the São Paulo State and the southeast of the Mato Grosso do Sul State. The objective of the present study was to analyze the composition and structure of community component of ectoparasites associated to a population of T. catalanensis located in Alegrete city, Rio Grande do Sul State, Brazil, aiming to evaluate the effects of this infestation on some aspects of the population. We analyze 315 lizards from Zoological Collection of Federal University of Santa Maria, collected between September/2007 and August/2008. The lizards were examined under a stereomicroscope and the prevalences and intensities of ectoparasites were quantified. Three species of ectoparasites were recorded: one tick, Ornithodoros fonsecai (Ixodidae) and two mites, Eutrombicula alfreddugesi and Microtrombicula sp. (Trombiculidae). Only mites were considered in analyzes. The total prevalence was 61.3% and a mean total intensity was 21.8 ± 37.5. Eutrombicula alfreddugesi had higher prevalence and Microtrombicula sp. a higher infestation intensity. Microtrombicula sp. used T. catalanensis dorsum, mostly, whereas E. alfreddugesi used its mite pockets in gular regions and armpits as the most common microhabitats. The prevalences and infestation intensities were significantly highest in hot season. The body size influenced the intensity of infestation in the lizards, with larger individuals having higher rates. The body condition differed among juveniles infested and non-infested by Microtrombicula sp., but was not related to the infestation rate. Males and females did not differ in infestation rates, but ontogenetic variation was observed with adults having higher prevalence and intensity of mite infestation. The infestation intensity did not differed between lizards with and without caudal autotomy. Pregnant females were more infested than non-pregnant ones, a result opposite to the expected, but the intensity did not affect the size and clutch mass. Factors such as saxicolous mode of life, age, body size, and the use of habitat in T. catalanensis, associated to some ecological and physiological characteristics of mite species, as well as climatic conditions of Pampa biome, with very low temperatures in cold season, can explain the results found in present study. The infestation patterns were significantly different from those already registered for Tropidurus, with the registration of two new ectoparasite species, so that long-term and under-sampled studies are essential for understanding the parasitic ecology of these lizards