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Two new species of Bachia of the bresslaui group are described from the central Brazilian Cerrados, state of Tocantins. The two species are most similar to Bachia bresslaui and Bachia cacerensis from which they differ in limb morphology and head scalation. In both, the snout is more prominent than that of previously known species, suggesting more pronounced adaptations to fossoriality. One of the new species has stiliform forelimbs and four clawed short toes in the hind limb, an opposite pattern to the condition observed in the genus where limb reduction is more pronounced in hind limbs. The two new species were obtained in relictual sandy soil areas covered by semidecidual or open dry forest vegetation. Considering the relictual condition of these sandy areas, the possible endemism to those areas, and the high level of disturbance of the Cerrados, we strongly suggest that these areas should be the target of special conservation efforts.
Bite force capacity is a directly related performance correlate of head shape and is an integrative measure of performance in capturing and handling prey, fighting, and mating, especially for males. We investigated head shape and bite force dimorphisms in a small semifossorial lizard (Elgaria coerulea) that exhibits females-larger sexual size dimorphism (FL-SSD) in some populations but not in others. Specifically, we explored how body size, head shape, and bite force compare between the sexes relative to any dimorphisms in body or head size in a coastal population of E. coerulea. Female larger-SSD was confirmed for this population, but it contrasted with males-larger sexual dimorphism in head size (ML-SDHS). Males also had greater bite force than females of similar size. The secretive habit of E. coerulea hampers observations of behavioral interactions among conspecifics. However, it is expected that lizards with FL-SSD will have ML-SDHS if males with greater bite force win fights with other males over access to mates and/or if greater bite force increases copulation success.
Snakes are often highly selective in the choice of sites for hibernation, and suitable sites can potentially be a limiting resource. Hibernating Louisiana Pine Snakes (Pituophis ruthveni; N = 7) in eastern Texas and Black Pine Snakes (Pituophis melanoleucus lodingi; N = 5) in Mississippi were excavated to characterize their hibernacula. Pituophis ruthveni hibernated exclusively in burrows of Baird's Pocket Gophers (Geomys breviceps), whereas P. m. lodingi hibernated exclusively in chambers formed by the decay and burning of pine stumps and roots. All snakes hibernated singly at shallow depths (P. ruthveni mean = 19 cm, max. = 25 cm; P. m. lodingi mean = 25 cm, max. = 35 cm). Pituophis taxa at higher latitudes and elevations hibernate communally and at greater depths. In contrast to Northern Pine Snakes (Pituophis melanoleucus melanoleucus), none of the pine snakes in our study excavated hibernacula beyond minimal enlargement of the preexisting chambers. These differences are presumably the result of mild winters, an abundance of suitable sites offering sufficient thermal insulation, and reduced predation risk caused by absence of communal hibernation in traditional sites. It is increasingly apparent that, throughout their annual cycle, pine snakes are dependent upon fire-maintained pine ecosystems.
We present the results of a taxonomic review of the four species of Allobates endemic to the Atlantic Forest Domain in Brazil. A total of 880 preserved specimens from 29 localities covering their range in Atlantic Forest were studied based on external attributes. Characters formerly described as diagnostic in original descriptions and others cited for dendrobatids in the literature were studied along the total geographic range of the populations of these species, including the type localities. We found no discrete characters, qualitative or quantitative, capable of differentiating the species. Most local and geographic variation was limited to snout-vent length and color pattern. Considering the lack of evidence otherwise, we use the results of our morphological analysis to allocate all Atlantic Forest species of Allobates to synonymy with Allobates olfersioides.
The tadpole of Melanophryne carpish is described based on two specimens found in an arboreal, water-filled bromeliad in humid montane forest at 2,870 m in the eastern Andes of northern Peru (Departamento de San Martín). It differs from all known New World microhylid tadpoles in having unpigmented, keratinized, jaw sheaths. The lower labium is expanded and platelike. The body is depressed with eyes located dorsally, and the spiracle is ventral. The presence of jaw sheaths suggests that the larvae might feed while undergoing development in aerial plants. The tadpole of Nelsonophryne aequatorialis is described based on a series of 17 specimens in Gosner Stages 37–42, which were found in a water canal in a pasture at 2,535 m in southern Ecuador (Departamento de Azuay). These tadpoles lack jaw sheaths and have a ventral spiracle with medial subdivision evident anterior to the gut. The tadpoles of M. carpish and N. aequatorialis are compared to one another, as well as other microhylid larvae. The nature of characters used to describe microhylid larvae, especially their mouthparts, is discussed and clarified.
Contamination of aquatic ecosystems with anthropogenic sources of nitrate is of increasing concern. Anurans are especially at risk for overexposure to nitrate because they occupy aquatic environments during embryonic, larval, and adult stages. Whereas there have been numerous studies examining the effect of nitrate on frog eggs and tadpoles, the effects of nitrate on adult frogs have been largely neglected. In this study, we examined whether brief exposure to environmentally relevant concentrations of aquatic nitrate influenced ovarian steroid synthesis and ovarian follicle size in adult African Clawed Frogs (Xenopus laevis). We exposed frogs for seven days to nitrate at concentrations of 24.8 or 49.5 mg/l in order to simulate a pulse of nitrate exposure. Relative to controls, nitrate-exposed frogs exhibited suppressed ex vivo synthesis of testosterone and estrogen. Follicles from nitrate-exposed frogs also exhibited an increased stage-4 diameter at both nitrate concentrations and a decreased stage-5 and -6 diameter at the highest nitrate concentration. These results indicate that anuran ovarian steroidogenesis and follicle size are modified by even a brief exposure to environmentally relevant concentrations of nitrate.
We present a new, plaster model for measuring operative environmental temperature (Te) and water loss of amphibians with little or no cutaneous resistance to water loss. These models are made from molds of live animals, cast in plaster of Paris, and can be fitted with water reservoirs that allow them to be used for extended periods. Plaster models did not differ significantly in Te or water loss rate from either identically shaped models made of 3% agar and measured in a wind tunnel or from live cane toads (Bufo marinus) measured outdoors in a variety of conditions. Thus, plaster models offer an accurate measure of both Te and water loss across a range of environmental conditions. The plaster models are also relatively simple to make and offer several advantages over other model types, in that they are durable, they do not shrink like agar models, they can be colored to match absorptivity of live animals, and they can be made in postures representative of live animals.
A new species of Eutropis (Sauria: Scincidae) is described from the island of Sulawesi, Indonesia, distinguished from all congeneric species, with the exception of Eutropis longicaudis, by its large size and low number of midbody scale rows. It has two primary temporal scales, whereas E. longicaudis from Borneo has only one. This new species is diurnal, partially arboreal, and inhabits rain forest from below 100 m to at least 600 m elevation.
Rhinella ocellata is a relatively unknown species of toad that occurs in Brazilian cerrado, a savanna-like biome. We studied home range and calling behavior of a population of this species in the state of Tocantins, Brazil, in 2004. Unlike most other species of bufonids, male R. ocellata did not migrate to ponds or other aquatic sites and form choruses for reproduction. Instead, R. ocellata had a prolonged breeding period during which males called from terrestrial sites typically on bare sandy soil near grass clumps or other shrubby vegetation. Calling sites were within open gallery forest in cerrado and ranged from 10–64 m from the shoreline of a river; similar calling sites were observed at another site in Tocantins in 2005. Home-range size was small compared to other toads that have been studied. Most individual R. ocellata remained within a small area during the study, typically calling nightly except during hot, dry periods. Calling bouts of R. ocellata consisted of an average of 36.9 short calls with fairly long intervals between bouts. Calling bout length averaged 31 sec. Neighboring individuals frequently alternated calls. One clutch of eggs found in a backwater pool of the river was tentatively identified as that of R. ocellata. The derived breeding behavior of R. ocellata is consistent with the historical difficulty in placing this species phylogenetically.
Clearcuts have been shown to adversely affect salamander populations, whereas impacts from milder forms of timbering are more variable. We determined the effects of clearcuts and shelterwood cuts on populations of the Peaks of Otter Salamander (Plethodon hubrichti) using counts of surface active salamanders found during multiple night collections. Sampling was done prior to and then periodically after timbering for 12 yr. Overall, the long-term trends in mean number of P. hubrichti at reference and shelterwood cut sites were not significantly different. In contrast, means at clearcut sites declined 41% during the first year posttimbering and then declined over the next three years to a low of 75% below pretimbering means. The means stabilized at 45% below pre-timbering means for the remainder of the study. Immediately after timbering 41% of the salamanders moved from transects established at the edge of clearcuts to reference transects that were 3–9 m away. Clearcuts had less canopy closure and dead leaf cover than reference and shelterwood cuts which likely degraded habitat for salamanders. Therefore, clearcutting forests is not advisable because of adverse impacts on salamanders, but forms of timbering that retain a portion of the forest canopy may be acceptable if it can be shown that the timbering method does not reduce salamander populations.
We document variation among 13 populations of distinct species of the lizard genus Xenosaurus in four key reproductive traits: minimum size at maturity, litter size, size at birth, and relative clutch mass (RCM). Despite a common flattened morphology, considerable variation occurs in the examined traits. Minimum size at maturity varied between 92 and 110 mm snout–vent length (SVL), average litter size ranged between 2.1 and 5.7 newborns per female, mean size at birth varied between 40.6 and 51.6 mm SVL, and average RCM ranged between 0.16 and 0.35. We also found considerable interpopulational variation in mean size of reproductive females (from 102.9–119.2 mm SVL) and in the length of the birth season (from about one month to four months distributed between early May and late September). Litter size and RCM were the most variable traits with coefficients of variation above 20, whereas the other traits showed coefficients of variation between 4 and 7.4. Only the minimum size at maturity showed an allometric effect. Litter size and size at birth were negatively correlated, which we interpret as evidence of a trade-off between these two traits. Cluster analyses revealed the existence of two main life-history strategies: populations with relatively large litters of small young and populations with small litters of large young. We suggest further ecological and phylogenetic analyses to explain the patterns of variation and covariation observed in the studied traits.
Growth and age at reproductive maturity are two life-history parameters that add an important temporal component to species conservation, yet such information is seldom available for plethodontid salamanders. We modeled growth and age at maturity for a northern West Virginia population of Green Salamanders, Aneides aeneus, using snout–vent length (SVL) growth intervals from a five-year mark-recapture study. Growth data were fit to the von Bertalanffy and logistic growth interval models and compared using the residual error mean square. The logistic model provided the best fit to the recapture data, indicating that Green Salamanders grow slowly for plethodontids and that it takes 7–8 yr to reach reproductive maturity. Our results revealed that Green Salamanders mature at a later age than most plethodontid species, indicating that the species might have greater generation time and longevity than previously suspected. Our data may offer insight into why the species is sensitive to population declines. Thus, we suggest that future research focus on Green Salamander longevity and generation time to provide a framework from which comparisons can be made across populations.
Fitness benefits to individuals from using a particular habitat during the non-breeding season are likely species- and habitat-specific. Our goal was to define the postbreeding habitat use of adult Wood Frogs (Rana sylvatica) within continuous oak-hickory forest in Missouri. We used radio-telemetry to determine whether adult Wood Frogs are evenly spaced throughout this forest type or clumped at a particular resource. In addition, we determined microhabitat selection using conditional logistic regression that compares the microhabitat at frog locations to paired points located 2 m from the frog. Adult frogs migrated from breeding sites located on ridgetops into ephemeral, rocky ravines. Use of drainages by Wood Frogs depended on the distance between the breeding site and drainage, and the orientation of drainages relative to the pond edge influenced whether migratory paths of frogs are funneled or spaced apart. The most supported model of microhabitat selection indicated that frogs selected locations with increased leaf litter depth and air temperature and with decreased humidity and light compared to paired points. Persistence of Wood Frog populations along the southwestern edge of their range requires successful annual migrations between breeding sites and forested drainages, which are important nonbreeding habitat for Wood Frogs in a Missouri oak-hickory forest.
If community structure is influenced by habitat structure at a local level, then it should be possible to tie species occurrence to key habitat variables. We used a pitfall-trap system to determine the relationship of species composition, species diversity (relative abundance), and community structure to habitat structure along a transect through a habitat gradient in the Brazilian Cerrado. A total of 531 individuals of 12 lizard species were sampled. A species accumulation curve based on EstimateS and a curve-fitting protocol predicted 12 species at day 22 and all species by about day 40. We registered 12 species at day 11. Trapping success declined through time, likely because of a combination of removal along the transect and seasonal environmental change (wet to dry). The more open end of our transect experienced higher temperatures in all microhabitats sampled, suggesting thermal structure associated with vegetative structure. A Canonical Correspondence Analysis showed that lizard species composition and relative abundance respond to variation in vegetative and physical structure of the habitat at small scales. Consequently, maintenance of habitat gradients should be considered in programs aimed at maintaining local biodiversity.
Using karyotypic, morphological, and molecular data, we compared Hynobius yunanicus with a sympatric species, Pachyhynobius shangchengensis. Similar to P. shangchengensis, H. yunanicus has a diploid chromosome number of 64, with five large pairs, six medium pairs, and 21 microchromosome pairs. In both H. yunanicus and P. shangchengensis, the vomerine teeth are arranged in two arched series, the lacrimals do not reach the orbits but are in touch with the external nares, and a gap between the pterygoid and maxillary is always present. The two species not only clustered together on a phylogenetic tree based on mitochondrial DNA sequence data but also share an identical haplotype. Therefore, H. yunanicus is not a valid species but a synonym of P. shangchengensis.
Detecting individuals of amphibian and reptile species can be a daunting task. Detection can be hindered by various factors such as cryptic behavior, color patterns, or observer experience. These factors complicate the estimation of state variables of interest (e.g., abundance, occupancy, species richness) as well as the vital rates that induce changes in these state variables (e.g., survival probabilities for abundance; extinction probabilities for occupancy). Although ad hoc methods (e.g., counts uncorrected for detection, return rates) typically perform poorly in the face of no detection, they continue to be used extensively in various fields, including herpetology. However, formal approaches that estimate and account for the probability of detection, such as capture-mark-recapture (CMR) methods and distance sampling, are available. In this paper, we present classical approaches and recent advances in methods accounting for detectability that are particularly pertinent for herpetological data sets. Through examples, we illustrate the use of several methods, discuss their performance compared to that of ad hoc methods, and we suggest available software to perform these analyses. The methods we discuss control for imperfect detection and reduce bias in estimates of demographic parameters such as population size, survival, or, at other levels of biological organization, species occurrence. Among these methods, recently developed approaches that no longer require marked or resighted individuals should be particularly of interest to field herpetologists. We hope that our effort will encourage practitioners to implement some of the estimation methods presented herein instead of relying on ad hoc methods that make more limiting assumptions.
We describe a strikingly distinct new species of Acutotyphlops from Kalinga Province of Luzon Island, Philippines. The new species is most closely related to other members of the genus Acutotyphlops from Papua New Guinea and the Solomon Islands and represents a new genus and species group record for the Philippines. A revised definition of Acutotyphlops is presented along with a synopsis of the genus. The discovery of this species, combined with consideration of its morphology and distribution, represents a curious new systematic and biogeographical problem in Southeast Asian and southwest Pacific scolecophidian snake systematics.
Typhlonectescompressicauda is a viviparous gymnophionan in which metamorphosis occurs during gestation. The development of the hypophysis and thyroid gland, both implicated in metamorphosis of other amphibians, has been poorly studied in gymnophionans. In this species, the adenohypophysis blastema, equivalent to Rathke's pouch, appears at stage 23. At stage 24, the anlage extends toward the diencephalon floor, forming a flat lens. At stage 26–27, at or just after hatching, the nerve fibers develop from the diencephalon, constituting the future pars nervosa. At the beginning of metamorphosis (stages 30–31), the differentiation of five endocrine cell types, resembling those of adult animals, is observed, suggesting the beginning of endocrine activity. The development of the thyroid gland from the pharyngeal endoderm, equivalent to the thyreoglosse canal, is first observed at stage 22. At stage 24, the anlage is divided into two lobes extending to the sinus venosus. At stages 26–27, a central lumen appears in the follicles. At stage 28, the morphology of the thyroid gland is that of an adult. Colloids fill the follicles at stages 29–30, before the threshold of metamorphosis. These observations suggest the association of development and activity of the thyroid gland with the metamorphic process, as in other Amphibia. A relative independence of thyroid endocrine activity with hypophyseal hormonal control (and consequently hypothalamus control) is suggested as in aquatic urodeles, at least at the beginning of metamorphosis.
We investigated the underlying mechanism of coexistence of two sympatric Japalura lizards (Japalura swinhonis and Japalura polygonata xanthostoma). We examined the differences in resource use along three resource dimensions: time, space, and diet. Specifically we tested two ecomorphological hypotheses. Correspondence exists between: perch habitat and limb morphology, and diet and head morphology. The species with shorter forelimbs would perch on narrower surface. The species with larger heads would consume larger or tougher prey. The results showed that the two species did not divide resources by temporal partitioning. Spatially, the two species used similar macrohabitats. However, female J. swinhonis, perching lower and on narrower surfaces, differed from other groups in perch habitats. However, male J. swinhonis and J. p. xanthostoma, despite size and shape differences, were similar in perch habitat. In addition, high diet overlap was detected both intra- and interspecifically despite the presence of significant differences in head sizes. In conclusion, male J. swinhonis and J. p. xanthostoma used largely overlapping resources and therefore, might be potential competitors if resources are limited. We suggest that there was a trade-off between fighting ability and maneuverability because of morphological differences that allowed the coexistence of the two species. Although male J. swinhonis, being larger, may have better fighting ability, J. p. xanthostoma could maneuver around tree trunks and branches to search for prey and avoid fighting more easily.
We describe a new species of Hydrolaetare from the eastern lowlands of Bolivia. The new species differs from the other two congeners in (1) Finger II and III with lateral fringes only on the inner side; (2) relative length of first finger; (3) palmar tubercle distinctly larger than thenar tubercle; (4) toes semiwebbed; and (5) coloration. Moreover, the advertisement call of the new species differs from that of its congeners. Some information about its natural history is given.
Two species of the Fringe-Toed Lizard, Uma exsul and Uma paraphygas, are restricted to small areas of sand dunes in the Chihuahuan Desert, where land cover transformation has increased dramatically in recent years and future climatic changes are expected to be severe. The current geographic distribution of each species was estimated by ecological niche modeling using the Genetic Algorithm for Rule-set Prediction (GARP). A recent land-use map was used to determine areas where habitat has been transformed by human activities, and niche models were projected under two simulated climatic scenarios and for two periods of time (2020 and 2050) to estimate their future potential distributions. Results indicate a high degree of anthropogenic habitat transformation within the distribution of U. exsul, and an important reduction of its distribution by 2050. For U. paraphygas land cover transformation is less severe, but a complete collapse of its current distributions is expected in the future because of climate change. Despite the uncertainty involved, the general trends seem highly feasible and immediate conservation actions are recommended.
Stream salamanders may play important roles as predators within streams, but we know little about actual predation by stream salamanders on other organisms. Because larval stream salamanders are more abundant within streams than adults, feed and forage throughout the year, and may spend multiple years in streams before transformation, larvae may play a more important role than adults in trophic interactions within streams. We conducted a study using larval Red Salamanders (Pseudotriton ruber) to determine (1) the prey composition of larval salamanders, (2) whether feeding rates are affected by stream water temperature, (3) whether larval size affects the diversity of prey items, and (4) whether nonlethal stomach flushing is an effective technique for examining the diet of larval salamanders. We found that larvae consumed a wide diversity of prey items including individuals of the families Chironomidae (36.52% of prey items) and Sphaeriidae (15.17%) as well as terrestrial prey (7.87%) and other salamanders (2.25%). We also found that feeding rates were negatively correlated with stream water temperature, and larger larvae consumed a wider diversity of prey items than smaller individuals. Our results also suggest that nonlethal stomach flushing did not affect survivorship. These findings suggest that larval Red Salamanders are generalist predators that can play important trophic roles in stream ecosystems.
Amphibians are declining globally at an unprecedented rate. Disease and climate change are implicated as causes of enigmatic declines. Batrachochytrium dendrobatidis (Bd) is an amphibian pathogen prevalent in the Neotropics and is commonly associated with declining populations. Another amphibian pathogen, ranavirus, has not been detected in the nontemperate areas of the Neotropics, but few investigators have sampled for it. We used molecular techniques to test for Bd and ranaviruses in two areas of Costa Rica with a history of amphibian declines. We detected Bd from field-sampled amphibians in Monteverde and Las Cruces, Costa Rica; ranaviruses were not detected in either area. Our results are consistent with the hypothesis that Bd was involved in declines at both sites, and provides additional information on its distribution in Costa Rica.
Florida is now home to several exotic species of amphibians and reptiles, but the most prevalent is Anolis sagrei, the Brown Anole. We surveyed 28 sites across the state for infections with the saurian malaria parasite, Plasmodium floridense between 2000 and 2006. Plasmodium floridense was found at five sites, primarily along the Gulf of Mexico coast. The results of the survey allowed for two tests of possible factors contributing to the presence of the parasite. One was a set of ecological variables as implemented in the niche modeling program Maxent. We found that proximity to fresh water and urban areas were important variables in predicting the parasite. The second test examined whether A. sagrei that had originated from western Cuban populations were less susceptible to the parasite; there was no difference in infection rates of A. sagrei from western versus eastern/central Cuban populations.
We surveyed all four extant North America populations of introduced Podarcis (Podarcis muralis and Podarcis sicula) for helminths and hematozoans; both parasite groups infect these lizards in their native European habitats. We found only small numbers of helminths and no hematozoans. We conclude that either these two Podarcis species did not bring many parasites with them, appropriate intermediate hosts are lacking, or that these populations have not been in North America long enough for new parasite faunas to become established.