Daniel Cunha Passos

Helminths Infection Patterns in a Lizard (Tropidurus hispidus) Population from a Semiarid Neotropical Area: Associations Between Female Reproductive Allocation and Parasite Loads

Abstract:  This study reports helminth infection patterns of the lizard Tropidurus hispidus from an area of semiarid caatinga in northeastern Brazil (Ceará state). The lizard population was parasitized by 8 helminth species, and the species composition of the component community resembles that found for other Neotropical lizards. The prevalence of parasites was higher for males compared with females, whereas no relation was found between intensity of infection of 2 parasites (Parapharyngodon alvarengai and Physaloptera lutzi) and the lizards body size. For reproductive females, parasite infection intensity was negatively correlated to reproductive investment.

Ecologia e história natural das serpentes de uma área de Caatinga no nordeste brasileiro

A fauna de serpentes do bioma Caatinga e uma das menos estudadas do Brasil. Estudamos a assembleia de serpentes de uma area de Caatinga arbustivo-arborea a fim de descrever a historia natural das especies ocorrentes na regiao. Um total de 636 individuos de 22 especies de quatro familias foi registrado. A distribuicao das abundâncias das especies na area e log-normal e a composicao apresenta serpentes tipicas de Caatinga sendo Oxybelis aeneus (Wagler, 1824) e Philodryas nattereri Steindachner, 1870 as especies mais comuns. A historia natural de cada especie e descrita a partir das informacoes sobre padroes de atividade, dieta, uso do ambiente, reproducao e repertorio defensivo obtidas durante o estudo e de informacoes disponiveis na literatura. A area de estudo esta em uma area prioritaria para conservacao e os resultados reforcam que politicas conservacionistas sejam aplicadas na regiao.

Levels of helminth infection in the flat lizard Tropidurus semitaeniatus from north-eastern Brazil

Parasites represent a great, unknown component of animal biodiversity. Recent efforts have begun to uncover patterns of infection by helminth parasites in several Neotropical lizards. The present study reports, for the first time, levels of helminth infection in a population of the flat lizard Tropidurus semitaeniatus. One hundred and thirty-nine lizards were examined and evidence of five intestinal helminth species was found, comprising four species of nematodes, one species of cestode and an unidentified encysted larval nematode. The most frequently occurring species was the intestinal nematode Parapharyngodon alvarengai, which did not exhibit differences in prevalence and intensity of infection relative to host sex or age/body size. Furthermore, helminth species richness was not related to host body size.

Efficiency of snake sampling methods in the Brazilian semiarid region

The choice of sampling methods is a crucial step in every field survey in herpetology. In countries where time and financial support are limited, the choice of the methods is critical. The methods used to sample snakes often lack objective criteria, and the traditional methods have apparently been more important when making the choice. Consequently researches using not-standardized methods are frequently found in the literature. We have compared four commonly used methods for sampling snake assemblages in a semiarid area in Brazil. We compared the efficacy of each method based on the cost-benefit regarding the number of individuals and species captured, time, and financial investment. We found that pitfall traps were the less effective method in all aspects that were evaluated and it was not complementary to the other methods in terms of abundance of species and assemblage structure. We conclude that methods can only be considered complementary if they are standardized to the objectives of the study. The use of pitfall traps in short-term surveys of the snake fauna in areas with shrubby vegetation and stony soil is not recommended.

New state record and distribution extension of the golden tegu Tupinambis teguixin (Linnaeus, 1758) (Squamata: Teiidae) to the Caatinga biome, northeastern Brazil

We expand the distribution of Tupinambis teguixin to the Caatinga biome, and report the first record of this species in Ceara state, northeastern Brazil. We found T. teguixin at a typical Caatinga habitat, approximately 215 km from the nearest locality with known record of the species. Our findings expand the knowledge of Caatinga’s herpetofauna, reinforcing the deficiency of information from several areas, and the necessity of additional surveys in this biome.

Indirect evidence of predation and intraspecific agression in three sympatric lizard species from a semi-arid area in northeastern Brazil

We analyzed the frequency of tail autotomy, toe amputation and integument scars in three sympatric lizard species, Ameivula ocellifera, Tropidurus hispidus and T. semitaeniatus, from a Neotropical area of semi-arid Caatinga, in northeastern Brazil. We evaluated intraspecific differences in the frequency of injuries between the sexes within each species. Only in A. ocellifera there were differences in frequency of toe amputation and integument scars between males and females, with more injured females than males. This highest frequency of body injuries in females of A. ocellifera might be attributed to the mating behavior of the species, in which males bite and scratch the females. None of the species analyzed presented intersexual differences in frequency of tail autotomy. These findings might be due to similar predation pressure upon males and females as suggested for other lizards species.

Survival of Amazonian Tadpoles Under Harsh Water-Limiting Conditions

Abstract. Tadpoles of some anuran species are known to survive out of water, but information is scarce or nonexistent for most species. We experimentally tested the survival ability of Amazonian tadpoles of six species out of water in conditions that simulated pond drying. Specifically, we tested the hypothesis that tadpoles typical of habitats subject to fast drying would have higher capacity to survive without free water. We found higher survival rates for some species that usually occur in temporary ponds and the lowest one for a species from perennial ponds. However, we also found species from temporary ponds and streams with intermediate tolerance to desiccation. Tadpole survival differed among species and increased in function of body mass but was not related to the probability of each species being subject to periods without water in their habitats. Therefore, we reject the hypothesis that tadpole survival in the absence of water is a simple function of the probability of ponds drying.

Challenges and Perspectives for Studies on Home Range of Lizards from South America

Abstract. Knowledge of home range is essential to understand the processes that govern space and social organization in animals. We analyzed the historical development of studies of lizard home range in South America in order to evaluate the extent of accumulated knowledge on this subject and to diagnose spatial patterns in the studied species. We found that the studies on home range of South American lizards are scarce, totaling only 18 publications. Furthermore, the accumulated information is both phylogenetically and geographically restricted, with the majority of studies focusing on species of Iguania and having been carried out in northwestern Argentina and southeastern Brazil. We conclude that the limitations of current knowledge impede the evaluation of patterns of space use for South American lizards. Based on this scenario, we provided a basic guideline to improve data gathering and analysis for future studies on home range of lizards from South America.

Activity patterns of the Brown Vine snake Oxybelis aeneus (Wagler, 1824) (Serpentes, Colubridae) in the Brazilian semiarid

The Brown Vine snake, Oxybelis aeneus (Wagler, 1824), is widely distributed from the United States to Argentina. 113 specimens encountered in the field and 39 individuals from scientific collections were analyzed and we determined patterns of diet, habitat use, and daily and seasonal activity. Oxybelis aeneus can be found to be active year round, especially during the dry and warmer months. Daily temperature poorly describes its activity as it seems to be more active around 31 to 35°C. During the hours of inactivity the species tends to chose higher branches than when active. The snakes choose spiny trees as retreat sites and spineless trees as foraging sites. We suggest that the high abundance of O. aeneus makes it an appropriate model organism for studies on activity patterns of snakes in semi-arid environments.