The role of spatial heterogeneity in diversity of squamate reptiles in the Atlantic Forest highlands of southeastern Brazil.

Spatial heterogeneity of vegetation is considered to be one of the most important factors that can influence species richness in a region and, therefore, an important driver for species diversity. Here, we investigate how squamate diversity varies throughout a heterogeneous area in southeastern Atlantic Forest. Our sampling site corresponded to a mosaic of forest and open fields in Curucutu nucleus, Serra do Mar State Park, São Paulo State, Southeastern Brazil. Species diversity varied throughout the mosaic in terms of species composition and relative abundance, with some species being clearly associated with a particular physiognomy. However, a decrease is observed in species richness in forest, after the rarefaction method is applied, showing that when the abundance effect is excluded, only species composition differed between physiognomies. On the other hand, both space and environmental heterogeneity were associated with diversity and distribution of squamates. Our results emphasize the importance of environmental heterogeneity, as well as the influence of the spatial location of the sample units, in structuring squamate diversity in a highland assemblage from the Atlantic Forest.

Reproduction in the pitviper Bothrops jararacussu: large females increase their reproductive output while small males increase their potential to mate.

Reproductive traits vary widely within and among snake species, and are influenced by a range of factors. However, additional studies are needed on several species, especially on tropical snake faunas, to fully understand the patterns of reproductive variation in snakes. Here, we characterized the reproductive biology of B. jararacussu from southeastern and southern Brazil. We combined macroscopic and microscopic examinations of the reproductive system of museum specimens with observations of free-ranging snakes to characterize size at sexual maturity, sexual size dimorphism (SSD), reproductive output, and male and female reproductive cycles. We compared our data with published literature and discuss the factors that may play a role in shaping the reproductive patterns in the species and the genus. Bothrops jararacussu shares several characteristics with its congeners such as autumn mating season, obligatory sperm storage in the female reproductive tract, seasonal timing of parturition (summer-autumn), female-biased SSD, maturity at larger body sizes in females, and a positive relationship between body size and litter size. These characteristics seem phylogenetically conserved in Bothrops. On the other hand, B. jararacussu exhibits some unique characteristics such as a high degree of SSD (one of the highest values recorded in snakes), a large female body size, and a large litter and offspring size, which are among the largest recorded in the genus. Moreover, larger females reproduce more frequently than smaller conspecifics. These characteristics may be collectively interpreted as the result of a strong selection for increased fecundity. Other peculiarities of the species include an asynchrony between spermiogenesis (summer-autumn) and the peak of SSK hypertrophy (autumn to spring) and a prolonged production of SSK granules. Because SSK hypertrophy and mating are androgen-dependent in snakes, the prolonged SSK hypertrophy suggests that male B. jararacussu may prolong their potential to mate (compared with its congeners), which may increase their reproductive success. Our results and previous literature collectively suggest that, in Bothrops, the evolution of SSD is driven by fecundity selection, variation in reproductive output is influenced by variation in female body size, and the timing of spermiogenesis is influenced by other factors in addition to temperature. We also suggest that male Bothrops have undergone multiple evolutionary shifts in the timing of spermiogenesis.

Composition and Natural History of Snakes from Etá Farm region, Sete Barras, south-eastern Brazil.

Approximately 140 snake species are known to occur in the Atlantic Forest with nearly half being endemic to this ecoregion. However, the Atlantic forest is one of the most threatened tropical ecoregions, with only 16% of its original area remaining as forest. This extensive habitat loss must have had a negative effect on its snake fauna. Indeed, 53% of the threatened snakes of Brazil occur in the Atlantic forest. Therefore, basic natural history information that can potentially contribute to the conservation of Atlantic forest snakes are urgently needed. Here the natural history of a snake assemblage at Etá Farm region, Sete Barras municipality, south-eastern Brazil is described, and a visual guide and an identification key provided that can be used by researchers and local people to identify snakes from this region. Most of the species found in the field use both open areas and forests, are primarily terrestrial, present diurnal activity, and include frogs in their diet. A higher number of enlarged follicles, eggs, and/or embryos were recorded during the warm and rainy season. Seventeen different types of defensive tactics were recorded in the species found in the field. This study provides useful information for understanding the structure of snake assemblages of the Atlantic Forest and is potentially useful for conservation assessments and for designing conservation plans.

Diversity, natural history, and geographic distribution of snakes in the Caatinga, Northeastern Brazil.

The present study is a synthesis on snake diversity and distribution in the Caatinga region of northeastern Brazil, providing an updated species list and data on natural history and geographic distribution. Our study is based on the careful revision of 7,102 voucher specimens, housed in 17 herpetological collections, complemented by data on taxonomic literature. We recorded a total of 112 snake species in the Caatinga, belonging to nine families: Anomalepididae, Leptotyphlopidae, Typhlopidae, Aniliidae, Boidae, Viperidae, Elapidae, Colubridae, and Dipsadidae. Our list includes at least 13 never recorded species for this region, as well as distribution records for all species known from the Caatinga (including expansion and new records of distribution). The snake assemblage of the Caatinga is complex, sharing species with other continental open areas (38.4%), forested areas (27.7%), and both open and forested areas (32.1%). The richest areas were isolated plateaus, followed by contact areas, semi-arid caatinga, and sandy dunes of the São Franscisco River. We identified 22 Caatinga endemic species with the sandy dunes of São Franscico River showing the highest endemism level (12 species, with six endemic species restricted to the area) followed by semi-arid caatinga, and isolated plateaus (eight endemic species each, and six and three endemic species with restricted distribution to each area, respectively). Most species show relatively restricted ranges in parts of the Caatinga. The snake assemblage in Caatinga includes mainly terrestrial species (38.4%), followed by fossorial/cryptozoic (26.8%), arboreal/semi-arboreal (26.8%), and aquatic/semi-aquatic (7.1%) species. Vertebrates are the most important dietary item (80.4%), with 56.6% of species being generalist consumers of this kind of prey; 24.4% are frog-eaters, 7.8% prey on caecilians/amphisbaenians, 6.7% lizard-eaters, 3.3% mammal-eaters, and 1.1% are fish-eaters. Only 18.7% of the snakes eat invertebrate prey, as arthropods, annelids, and mollusks. In relation to time of activity, 35.7% of snakes are both diurnal and nocturnal, 33.0% are strictly nocturnal, and 30.4% are diurnal. The data provided herein increase the list of Caatinga snake species from 50 to 112, and includes detailed maps and information on geographic distribution. The Caatinga snake assemblage shows high richness and endemism levels, and our results highlight the usefulness of basic natural history data and revision of voucher specimens as baseline information for biogeographic studies and conservation strategies. 

The golden lancehead Bothrops insularis (Serpentes: Viperidae) relies ontwo seasonally plentiful bird species visiting its island habitat

Adult individuals of the island pitviper Bothrops insularis have a diet based onbirds. We analysed bird species recorded in the gut of this snake and found that it relies on two out of 41 bird species recorded on the island.When present, these two prey species were among the most abundant passerine birds on the island. A few other migrant birds were very occasionally recorded as prey. A resident bird species(Troglodytes musculus) is the most abundant passerine on the island, but seems able to avoid predation by the viper. Bothrops insularis is most commonly found on the ground. However, during the abundance peak of the tyrannid passerine Elaeniachilensis on the island, more snakes were found on vegetation than on the ground. We suggest that one cause may be that these birds forage mostly on vegetation, and thus cause the snakes to search for prey on this arboreal substratum.

When Basking Is Not an Option: Thermoregulation of a Viperid SnakeEndemic to a Small Island in the South Atlantic of Brazil

It is broadly accepted that snakes are able to regulate their body temperature (Tb) behaviorally, but fundamentaldifferences in this ability have been suggested to exist between temperate and tropical species. Herein, we examined the thermal ecology of the Golden Lancehead, Bothrops insularis, a critically endangered Neotropical crotaline snake endemic to Queimada Grande Island (QGI), southeastern Brazil. We sampled Tb’s of individual snakes found in the field and tested which proximal factors, biotic and abiotic, were potentially relevant for their thermoregulatory behavior and Tb selection. We verified whether Tb regulation would be compensated, through the day and/or seasons, by adjustments in the thermoregulatory effort. Finally, we hypothesized that for a Neotropical snake, the thermoregulatory effort would be lower because the thermal quality of habitat is higher compared to species inhabiting temperate zones. In general, B. insularis conformed to this hypothesis. However, seasonal declines in the thermal quality of habitat during the colder seasons and during nighttime were compensated by increases in the effectiveness of thermoregulation. Overall, Tb of B. insularis is determined largely by environmental variables, particularly air temperature, with some influence of biotic factors, such as body size. Use of open areas for basking, a common thermoregulatory behavior for squamates, was largely avoided; this may be explained by ecological factors, and may be due to foraging constraintsand increased risks of predation and dehydration.

Reptilia, Squamata, Serpentes, Dipsadidae, Tropidodryasstriaticeps (Cope, 1869): Latitudinal and altitudinal extension and geographic distribution map

We report here the northernmost record of Tropidodryas striaticeps (Cope, 1869) extending the speciesdistribution northwards from the previously known localities. We also provide data about altitudinal distribution of T. striaticeps, extending its occurrence to altitudes lower than 150 m a.s.l. In addition, this is the first confirmed record of T. striaticeps for the Caatinga ecorregion and the fourth one for the state of Bahia. An updated distribution map is alsoprovided.

Does gestation or feeding affect the body temperature of the golden lancehead, Bothrops insularis (Squamata: Viperidae)under field conditions?

Temperature affects physiological performance in reptiles and, therefore, body temperature (Tb) control isargued to have an important adaptive value. Alterations in Tb due to transient changes in physiological state, as duringdigestion or gestation, are often linked to the potential benefits of a more precise Tb regulation. However, such thermoregulatory responses in nature remain controversial, particularly for tropical snakes. Herein, we measured Tb of the golden lanceheads, Bothrops insularis (Amaral, 1921), at Queimada Grande Island, southeastern Brazil, to test for alteration in selected body temperatures associated with feeding or gestation. We found no evidence that postprandial or gravid snakes selected for higher Tb indicating that, under natural conditions, body temperature regulation in B. insularis apparently encompasses other ecological factors beyond physiological state per se.

Reproductive biology and food habits of Pseudoboa nigra (Serpentes Dipsadidae) from the Brazilian cerrado / Biologia reprodutiva e hábitos alimentares de Pseudoboa nigra (Serpentes Dipsadidae) do cerrado brasileiro

Reproductive biology and food habits of Pseudoboa nigra (Serpentes: Dpsadidae) from the Brazilian cerrado. Herein we provide data on body size, sexual size dimorphism, reproductive cycle, and food habits of the pseudoboini snake Pseudoboa nigra, wich is dissections of 147 preserved specimens, it is shown that femmales attain, and mature at, larger body sizes than males. There is no significant sexual dimorphism in head lenght, but males have longer tails to their body sizes. Vitellogenesis, egg-laying, and sperm production occur throughout the year, but males do not exhibit long-term sperm storage. The main prey of P. nigra is lizards; there is no evidence of ontogenetic change or sex differences in the diet of this species.

Biologia reprodutiva e hábitos alimentares de Pseudoboa nigra (Serpentes: Dipsadidae) do cerrado brasileiro. Neste trabalho fornecemos informações sobre tamanho corporal, dimorfismo sexual, ciclo reprodutivo e hábitos alimentares da serpente Pseudoboini Pseudoboa nigra, que corre no domínio do Cerrado na região Central da América do Sul. Com base na dissecção de 147 espécimes preservados, mostramos que as fêmeas são em média maiores e atinguem maturidade sexual com maior tamanho corporal que os machos. O dimorfismo sexual não foi significativo para o tamanho da cabeça, mas os machos possuem caudas relativamente mais longas que as fêmeas. A vitelogênese, a postura de ovos e a espermatogênese ocorrem durante todo o ano, e os machos não armazenam esperma no ducto deferente por longos períodos. A principal presa dessa espécie são lagartos; não há evidencias de variação ontogenética ou de diferenças relacionadas ao sexo na dieta dessa espécie.

Tail Luring by the Golden Lancehead (Bothrops insularis), an Island EndemicSnake from South-Eastern Brazil

Herein, we report on direct and indirect evidence of tail luring by the golden lancehead, Bothrops insularis (Viperidae), a threatened snake species endemic to a small island off the coast of South-eastern Brazil. Tail luring was recorded for a juvenile male in nature and circumstantial evidence indicates that it was directed to ectothermic prey. Indeed, B. insularis juveniles feed on small lizards and frogs and tail luring is probably an important hunting strategy of this species. Adult golden lanceheads prey mostly on birds. A frequently seen characteristic ambush posture, coiled with the conspicuous tail tip exposed close to the head, indicates that they use tail luring as well. Lured birds may peck at a snake's tail, and the high frequency of tail tip injuries in B. insularis (20.9%) compared to a continental sister species that rarely preys on birds (B. jararaca, 7.3%) strengthens the view that B. insularis adults lure birds.

A First Estimate of the Population Size of the Critically Endangered Lancehead, Bothrops insularis

Although Bothrops insularis is critically endangered, there is no estimate of its population size based on fieldquantifications. Here we provide the first estimate of its population size based on plot surveys conducted at the Queimada Grande Island. We distributed 26 quadrat plots regularly in a trail that crosses the island. Plots were sampled twice in 2002. Of the 26 plots we sampled, 21 were located in forests and five in grassy areas. For the first survey, mean estimates of population size forplots located in forests and grassy areas were 2134.3 and 224.0 snakes, and the Percentage Relative Precision for these estimates were 38.6% and 277.6%, respectively. For the second survey, no snakes were found in grassy areas, whereas the mean estimate ofpopulation size for plots located in forests was 1304.3 snakes and the Percentage Relative Precision for these estimates was 93.7%. Although suffering from relatively low precision, our best estimate of population size in B. insularis is around the lower end of the guesses found in the literature (2000‑4000 individuals for the entire island). Furthermore, based on encounter rates obtained in a non-systematic way in the last 12 years, we have the impression that the density of B. insularis decreased in this period and we have evidence for the illegal removal of snakes from the island in the last few years. Our results suggest the urgent need of enforcement to restrain the illegal removal of snakes from the island and of a monitoring program to track future changes in the population size of B. insularis.

A new insular species of pitviper from Brazil, with comments on evolutionary biology and conservation of the Bothrops jararaca group ( Serpentes, Viperidae)

We describe a new pitviper species, Bothrops alcatraz, of the Bothrops jararaca group, from Alcatrazes Island, off the coast of São Paulo, southeastern Brazil. It differs from the mainland coastal populations of B. jararaca in southeastern Brazil mostly by its darker coloration; smaller size; lower number of ventrals, subcaudals, and infralabials; number and shape of anterior cephalic scales; shape of hemipenis spines; intense coagulant activity of venom; and three specific venom proteins. From Bothrops insularis, another island species from southeastern Brazil, the new species differs mainly by its color pattern, smaller size, lower number of subcaudals in males, and absence of hemiclitoris in females. Bothrops alcatraz presents some features that may be viewed as paedomorphic within the B. jararaca group, such as small adult size, proportionally large eyes,intense coagulant venom activity, and diet composed of centipedes and lizards. We postulate that the dwarfism and characteristics of venom in B. alcatraz may be related to its diet (similar to thatof juveniles of the mainland B. jararaca). Bothrops alcatraz and B. insularis may have originatedthrough the isolation of populations of a B. jararaca-like ancestor on the Alcatrazes and Queimada Grande islands, respectively. The new species is regarded as critically endangered due to its very small area of occurrence and the declining quality of its habitat.