Helga C. Wiederhecker

Diet of Epipedobates flavopictus (Anura: Dendrobatidae) in a Neotropical Savanna

Abstract A central issue in comparative biology is identifying the relative importance of historical (phylogenetic) versus present-day (ecological) factors in shaping phenotypic traits of organisms. Herein, we investigate effects of sex, ontogeny, and season on diet of Epipedobates flavopictus, a species restricted to open landscapes in central Brazil. Based on prey frequency, number, and volume, the most important prey categories were ants, termites, beetles, spiders, and orthopterans. Prey number and volume increased significantly with snout–vent length (SVL), and the consumption of termites also increased with SVL. There were few effects of sex and season upon diet composition, average prey number, or average prey volume, all independent of SVL. Reproductive females consumed larger prey, in great numbers, likely to increase energy uptake. As is true for most congeners, as well as species of closely related genera, ants are an important component in the diet of E. flavopictus. However, in contrast to its forest relatives, E. flavopictus consumes large amounts of termites, revealing the influence of prevailing ecological conditions. The small volume of ants in the diet of E. flavopictus and the high toxicity of its skin are not in agreement with the hypothesis of a causal relationship between skin toxicity and ant consumption.

Reproductive Ecology of Tropidurus torquatus (Squamata: Tropiduridae) in the Highly Seasonal Cerrado Biome of Central Brazil

Abstract We studied the reproductive cycle of Tropidurus torquatus in the Cerrado biome of central Brazil from October 1997 to September 1998. Females reached sexual maturity at about 65 mm snout–vent length (SVL), whereas males became sexually mature at 70 mm SVL. Females were reproductively active between August and February, although males contained spermatozoa in the epididymides year-round. Frequency of reproductive females was inversely correlated with precipitation and air humidity and positively correlated with day length. Reproductive activity of males was inversely correlated with air humidity and positively correlated with day length. Females laid six eggs on average and may have produced up to three clutches per reproductive season. With the advancement of the reproductive season, clutches tended to be smaller, whereas egg size remained constant. Fat body mass varied inversely with reproductive activity in both sexes, but females had significantly larger values than males. After an incubation period of approximately 5 months, young emerged at a SVL around 31 mm. Juveniles began to accumulate energy in fat bodies after reaching 47 mm SVL. The fat body cycle and the recruitment pattern of T. torquatus suggest that food resources are not limiting and that the length of the reproductive season is most likely constrained by the availability of microhabitats suitable for egg development.

Sexual dimorphism in the Neotropical lizard, Tropidurus torquatus (Squamata, Tropiduridae)

Abstract. We describe the sexual dimorphism in coloration, body shape, and body size in Tropidurus torquatus ,awidelydistributed lizard species in central Brazil. Adult males have colored patches varying from yellow to yellow-and-black, andblack on the abdomen, ventral aspect of the thighs, and pre-cloacal sap. Adult females lack ventral colored patches. Duringontogeny, there is a gradual darkening of the patches, but no modiÞcation either in patch size or color is associated with thereproductive cycle. Adult males have wider heads and thinner bodies than females of the same body size. Males and femalesgrow at the same rate prior to sexual maturity, but males take longer to reach sexual maturity, maturing at a larger body sizethan females. IntroductionSexual dimorphism is a widespread featureamong lizards, as in many other groups ofanimals. Male and female lizards may dif-fer in many traits, such as coloration, bodyshapeandsize.Thesedifferenceshavegenerallybeen attributed to the effects of sexual selec-tion (Andersson, 1994), but other mechanisms,such as ecological divergence (Schoener, 1967;Schoener and Gorman, 1968; Shine, 1991) andfecundity selection (Shine, 1992; Olsson et al.,2002), offer alternative explanations for sexualdimorphism (Shine, 1989).Color patterns can be linked to several as-pects of the ecology of a species (Cooper andGreenberg, 1992). For example, dorsal col-oration has often been associated with anti-predatoryandthermoregulatorybehaviors(Nor-ris and Lowe, 1964; Porter and Tracy, 1983),whereas ventral and lateral colors seem to beemployed in intra- (Lemos-Espinal et al., 1996;Cuadrado,2000;Galan,2000)andinter-speciÞcsignaling (Losos, 1985). In adult males, ven-tral and lateral coloration is often conspicvous,being exhibited in intra-speciÞc encounters asdominance displays (Zucker, 1989) or as an aidin sexual identiÞcation (Cooper and Vitt, 1988;

A CRITICALLY ENDANGERED NEW SPECIES OF CNEMIDOPHORUS (SQUAMATA, TEIIDAE) FROM A CERRADO ENCLAVE IN SOUTHWESTERN AMAZONIA, BRAZIL

We describe a new species of Cnemidophorus from a Cerrado enclave in southwestern Amazonia, Rondônia state, Brazil. This species is apparently endemic to Cerrado enclaves in the vicinity of the city of Vilhena, a region under intensive anthropic pressure due to the expansion of soybean plantations. A discriminant analysis indicated that femoral pores and scales around the tail are the best discriminators among Brazilian species of Cnemidophorus. A naïve Bayesian network constructed with categorical (mostly coloration) variables indicated that the new species had high conditional probabilities of dorsolateral fields absent, vertebral field spotted, and paravertebral lines absent. The analyses revealed clear distinctions between species of Cnemidophorus that range north and south of the the Amazon River. The new species may have evolved as a result of vicariance, following the isolation of peripheral enclaves of Cerrado in southwestern Amazonia after the late Pleniglacial. The restricted range in small areas, under extreme human pressure around Vilhena, makes this species one of the most critically endangered elements of the Brazilian herpetofauna.

Spermiogenesis and testicular cycle of the lizard Tropidurus torquatus (Squamata, Tropiduridae) in the Cerrado of central Brazil

We studied the spermiogenesis and testicular cycle of the lizard Tropidurus torquatus , using light and electron microscopy. Males bearing spermatozoa were present practically year-round and spermatogenic activity showed a regenerative phase from late dry season to the end of the rainy season (July to March), with low frequency of initial stages of the spermatogenic cycle, and a brief degenerative phase from April to June, lacking the total regression of seminiferous tubules. These characteristics resemble those from species with continuous reproductive cycles, contrasting with the strongly seasonal reproductive cycle of females. Spermiogenesis includes nuclear elongation, chromatin condensation, acrosomal and flagellar development, and elimination of excessive cytoplasm. We describe some new aspects in the spermiogenesis of T. torquatus , including the interaction between spermatid and Sertoli cell, acrosomal granule, subacrosomal granule, and the fibrous sheath formation. The testicular cycle of T. torquatus is very similar to that of other lizards that inhabit seasonal environments, and its spermiogenesis and ultrastructure of mature sperm display a number of conservative features.

Reproduction, Body Size, and Diet of Polychrus acutirostris (Squamata: Polychrotidae) in Two Contrasting Environments in Brazil

Abstract We compared reproduction, diet, and body size of Polychrus acutirostris (Squamata: Polychrotidae) from the Cerrado and Caatinga biomes in Brazil. Because these two biomes have widely different climates, we predicted that lizards in Caatinga would produce smaller clutches in response to rainfall unpredictability. We also expected reproductive timing to differ between biomes, with lizards occurring in the Cerrado producing a single clutch in association with the predictable rains of October–November. Contrary to expectations, clutches had fewer (although larger) eggs in Cerrado. Reproductive period was remarkably similar (peak of female reproductive activity in November), but female reproduction started 1 month earlier in Cerrado. Diet composition was also similar, with the exception of spiders, that exhibited a high index of relative importance in Cerrado but were nearly absent in Caatinga lizard diets. Lizards from both biomes ingested a large proportion of plant material, as well as soft-bodied arboreal arthropods, such as orthopterans, and mostly slow-moving, large arboreal insects. Rainfall predictability in the Cerrado therefore did not influence Polychrus reproduction or diet in the same manner as in other lizard species. The large number of small eggs in the Caatinga suggests that the competitive environment for offspring is either unpredictable or that mortality is high but random. Rain forest Polychrus lizards produce few large eggs, suggesting that the competitive environment for offspring is predictably intense and mortality is non-random. Cerrado Polychrus lizards seem intermediate between Caatinga and rain forest Polychrus lizards, producing fewer and larger eggs than their conspecifics in the Caatinga but relatively more and smaller eggs than rain forest Polychrus species.