Nematode parasites of the Brazilian sand lizard, Liolaemus lutzae

Abstract

Liolaemus lutzae is a small (hatchlings=30-31.0 mm; juveniles up to 50.0 mm and adults up to 80.0 mm SVL) tropidurid lizard endemic to the ofthe Rio deJaneiro State in Brazil (Rocha, 1989). Restingas are Quaternary coastal ridges with salt-sand substrate covered with herbaceous and shrubby vegetation (Suguio and Tessler, 1984). These formations are common along the Brazilian coast. Liolaemus lutzae has a narrow geographic distribution, occurring along only approximately 200 km of coast (Rocha, 1986). It is the only lizard species living on the beach habitat (50-l 00 m wide strips of sand covered with herbaceous vegetation, at seaside) of the restingas in which itoccurs (Rocha, 1988). The diet of L. lutzae consists of plants and soil arthropods but plant material predominates (70-l 00% by volume) in adults diet (Rocha, 1989). The species is presently considered to be threatened with extinction, having been recently included in the checklist of Brazilian threatened fauna (Bernardes et al., 1990). This study reports the prevalence and intensity of infection with nematode parasites in these lizards, and evaluates the relationship between prevalence of infection and rainfall. I examined the alimentary tract of l78 (x=61.1:t10.0 mm SD) lizards of the reptile collection of the Setor de Ecologia that were previously collected for a study of feeding habits. The Restinga da Barra de Marica (22°57'S, 43°50'W) is located approximately 38 km east of Rio de Janeiro City, Rio de Janeiro State, southeastern Brazil. The L. lutzae of the collection were collected in monthly samples from December 1985 to November 1986. The stomach and small and large intestine were removed, slit longitudinally and systematically examined under a dissecting microscope. Nematodes were mounted in glycerol. Voucher specimens were deposited in the helminthological collection ofthe Funda;jo Instituto Oswaldo Cruz -FIOCRUZ, under the numbers 32820 a-c and 3282l a-e. Data on rainfall in the area were obtained from the Departamento Nacional de Aguas e Energia Eletrica, Station of Niteroi, located approximately 19 km west from the study area. I found two species of nematodes in the digestive tract of L. lutzae: Physaloptera retusa Rudolphi, l8l9, in the stomach and Pharyngodon cesarpintoi Pereira, 1975, which was found in the large intestine. Both species represent a new host record. Overall prevalence of infection by nematodes in L. lutzae was l3.5%, but only one lizard (0.6%) contained both species of nematode. P. retusa had a prevalence of 9.6% while that of P. cesarpintoi was 4.5%. The prevalence of P. retusa varied seasonally. Infected lizards occurred from December to July with a peak in February (fig. I). Rainfall in the area also varied seasonally, most rain falling between November and