Total-evidence phylogeny and evolutionary morphology of New World pitvipers (Serpentes: Viperidae: Crotalinae).

Crotalines (pitvipers) in the Americas are distributed from southern Canada to southern Argentina, and are represented by 13 genera and 163 species that constitute a monophyletic group. Their phylogenetic relationships have been assessed mostly based on DNA sequences, while morphological data have scarcely been used for phylogenetic inquiry. We present a total-evidence phylogeny of New World pitvipers, the most taxon/character comprehensive phylogeny to date. Our analysis includes all genera, morphological data from external morphology, cranial osteology and hemipenial morphology, and DNA sequences from mitochondrial and nuclear genes. We performed analyses with parsimony as an optimality criterion, using different schemes for character weighting. We evaluated the contribution of the different sources of characters to the phylogeny through analyses of reduced datasets and calculation of weighted homoplasy and retention indexes. We performed a morphological character analysis to identify synapomorphies for the main clades. In terms of biogeography, our results support a single colonization event of the Americas by pitvipers, and a cladogenetic event into a Neotropical clade and a North American/Neotropical clade. The results also shed light on the previously unstable position of some taxa, although they could not sufficiently resolve the position of Bothrops lojanus, which may lead to the paraphyly of either Bothrops or Bothrocophias. The morphological character analyses demonstrated that an important phylogenetic signal is contained in characters related to head scalation, the jaws and the dorsum of the skull, and allowed us to detect morphological convergences in external morphology associated with arboreality.

Thermoconformity strategy in the freshwater turtle Hydromedusa tectifera (Testudines, Chelidae) in its southern distribution area.

Ectotherm species are not capable of generating metabolic heat; therefore, they present different strategies for regulating their body temperatures, ranging from a precise degree of thermoregulation to a passive thermoconformity with ambient temperatures. In reptiles, aerial basking is the most common mechanism for gaining heat. However, among aquatic reptiles, such as freshwater turtles, aquatic basking is also frequent. Hydromedusa tectifera is a turtle of exclusively aquatic and nocturnal habits widely distributed in South America. We studied the relationship between body temperature (Tb) of H. tectifera and its habitat, and explored the effects of sex, life stage and body size and mass on Tb. Fieldwork was conducted in two streams of a mountain area of central Argentina. We recorded cloacal temperature, size and mass of 84 turtles. We also determined individuals' sex and life stage (adult/juvenile). Regarding ambient temperatures, we measured water temperature on the surface (Tsurf) and at depth of turtle capture (Tdepth) and air temperature. Mean Tb was 18.58°C (Min = 10.20°C; Max = 25.70°C). Tsurf and Tdepth were highly correlated. Multi-model analysis using Akaike criterion indicated that Tb was strongly associated with water temperature, whereas air temperature and body size and mass did not show a significant effect. There was also no effect of turtle sex or life stage on Tb. Our results indicate that H. tectifera is a thermoconformer and eurythermal species. A nocturnal pattern of activity and a fully aquatic lifestyle are suggested as determinant factors.

Is thermal sensitivity affected by predation risk? A case study in tadpoles from ephemeral environments.

Changes in environmental temperature may induce variations in thermal tolerance and sensitivity in ectotherm organisms. These variations generate plastic responses that can be analyzed by examining their Thermal Performance Curves (TPCs). Additionally, some performance traits, like locomotion, could be affected by other factors such as biological interactions (e.g., predator-prey interaction). Here, we evaluate if the risk of predation modifies TPCs in Mendoza four-eyed frog (Pleurodema nebulosum, Burmeister, 1861) and Guayapa's four-eyed frog (Pleurodema guayapae, Barrio, 1964), two amphibian species that occur in ephemeral ponds in arid environments. We measured thermal tolerances and maximum swimming velocity at six different temperatures in tadpoles under three situations: control, exposure to predator chemical cues, and exposure to conspecific alarm cues. TPCs were fitted using General Additive Mixed Models. We found that curves of tadpoles at risk of predation differed from those of control mainly in thermal sensitivity parameters. Our work confirms the importance of biotic interactions have in thermal physiology.

How far from water? terrestrial dispersal and nesting sites of the freshwater turtle Phrynops hilarii in the floodplain of the Paraná River (Argentina).

Terrestrial environments surrounding aquatic resources are important and intensively used by semi-aquatic species. In the present work, terrestrial dispersal and nesting sites of the freshwater turtle Phrynops hilarii were analyzed in the floodplain of the Paraná River, using field data and variables obtained from remote sensing. A total of 112 turtles and 44 nests were recorded during road sampling for one year (covered a total of 786 km in 30 surveys). Individuals were at a mean distance of 171.45 m from water, with a negative correlation between number of turtles and distance from water bodies. No significant differences in distance of turtles from water were observed among seasons. Phrynops hilarii nested at a mean distance of 136.51 m from water, showing a negative correlation between number of nests and distance from water bodies. Mean elevation of nests relative to maximum level of water body nearest each record was 1.13 m. The correlation between number of nests and elevation of the nearest water body was positive and significant. The landscape surrounding wetlands is important for P. hilarii to complete the life cycle, as nesting is done in this environment. Our results show that the habitat selected for nesting and terrestrial dispersal was proportionally different from that available in the entire study area, with a higher proportion of wetlands, grasslands and forests.

Patterns of morphological variation and ecological correlates in the skull of vipers (Serpentes: Viperidae).

The skull of vipers is a highly kinetic anatomical structure involved in envenomating and consuming of prey. Morphological knowledge about the viperid skull is based on studies on some groups of species, but information on its variation within the whole family and its functional morphology is still scarce. In this study, we aimed to explore variation in skull morphology among species of the three subfamilies of Viperidae, and test whether that variation correlates with macrohabitat and diet. We performed quantitative analyses of the viperid skull based on broad taxonomic sampling and two methodological approaches: linear and geometric morphometrics. The results of both approaches showed that much of the variation lies in differences of shape and relative size of the premaxilla, the nasals, the frontals, and the parietals. The results indicated that phylogeny and size influence the shape of the skull, but we also found evidence of morphological differentiation between arboreal and terrestrial species and in species with mammal specialist diet. Our findings imply that, besides evolutionary allometry and phylogenetic signal, demands of particular diets coupled with use of certain habitats have in part shaped morphological evolution of the viperid skull.

A new species of Bothrops (Serpentes: Viperidae: Crotalinae) from Pampas del Heath, southeastern Peru, with comments on the systematics of the Bothrops neuwiedi species group.

We describe a new species of pitviper of the genus Bothrops from the Peruvian Pampas del Heath, in the Bahuaja-Sonene National Park. Pampas del Heath is an area of seasonally flooded savannas and a northwestern extension of the Gran Chaco Boliviano-Paraguayo. The new species is easily distinguished from its congeners by the exclusive combination of dorsal color pattern of body consisting of small C-shaped blotches, postocular stripe originating posteriorly to the eye, covering posterior supralabials, dorsum of the head with paired markings arranged symmetrically, venter cream heavily speckled with brown, prelacunal scale discrete in contact with second supralabial, three to five prefoveals, subfoveal single usually present, postfoveals absent to two, canthals two, seven intersupraoculars, one or two suboculars, two or three postoculars, seven or eight supralabials, nine to eleven infralabials, 26-27 interrictals, 23-25 middorsal scales, 172 ventrals in the female and 169-173 in males, 45 subcaudals in the female and 50 in males. We performed separate and combined phylogenetic analyses based on morphology and five mitochondrial genes and recovered the new species as a member of the Bothrops neuwiedi species group. All lineages of this clade inhabit the South American dry diagonal. This novel species of pitviper increases the known diversity of the genus Bothrops and adds to the number of described taxa from the unique and scarcely known ecosystem of Pampas del Heath.

Identification of limiting climatic and geographical variables for the distribution of the tortoise Chelonoidis chilensis (Testudinidae): a baseline for conservation actions.

Background. Just as for most other tortoise species, the once common Chaco tortoise, Chelonoidis chilensis (Testudinidae), is under constant threat across it distribution in Argentina, Bolivia and Paraguay. Despite initial qualitative description of the species distribution and further individual reports of new locations for the species, there is no description of the species distribution in probabilistic terms. With this work we aim to produce an updated predictive distribution map for C. chilensis to serve as a baseline management tool for directed strategic conservation planning. Methods. We fitted a spatially expanded logistic regression model within the Bayesian framework that accounts for uncertainty on presence-only and generated pseudo-absence data into the parameter estimates. We contrast the results with reported data for the national networks of protected areas to assess the inclusion of the species in area-based conservation strategies. Results. We obtained maps with predictions of the occurrence of the species and reported the model's uncertainty spatially. The model suggests that potential suitable habitats for the species are continuous across Argentina, West Paraguay and South Bolivia, considering the variables, the scale and the resolution used. The main limiting variables were temperature-related variables, and precipitation in the reproductive period. Discussion. Given the alarming low density and coverage of protected areas over the distribution area of C. chilensis, the map produced provides a baseline to identify areas where directed strategic conservation management actions would be more efficient for this and other associated species.

Climate change and American Bullfrog invasion: what could we expect in South America?

BACKGROUND: Biological invasion and climate change pose challenges to biodiversity conservation in the 21(st) century. Invasive species modify ecosystem structure and functioning and climatic changes are likely to produce invasive species' range shifts pushing some populations into protected areas. The American Bullfrog (Lithobates catesbeianus) is one of the hundred worst invasive species in the world. Native from the southeast of USA, it has colonized more than 75% of South America where it has been reported as a highly effective predator, competitor and vector of amphibian diseases. METHODOLOGY/PRINCIPAL FINDINGS: We modeled the potential distribution of the bullfrog in its native range based on different climate models and green-house gases emission scenarios, and projected the results onto South America for the years of 2050 and 2080. We also overlaid projected models onto the South American network of protected areas. Our results indicate a slight decrease in potential suitable area for bullfrog invasion, although protected areas will become more climatically suitable. Therefore, invasion of these sites is forecasted. CONCLUSION/SIGNIFICANCE: We provide new evidence supporting the vulnerability of the Atlantic Forest Biodiversity Hotspot to bullfrog invasion and call attention to optimal future climatic conditions of the Andean-Patagonian forest, eastern Paraguay, and northwestern Bolivia, where invasive populations have not been found yet. We recommend several management and policy strategies to control bullfrog invasion and argue that these would be possible if based on appropriate articulation among government agencies, NGOs, research institutions and civil society.

[Identifying areas of high risk for ophidism in Cordoba, Argentina, using SIGEpi software]. / Identificación de las zonas de riesgo ofídico en Córdoba, Argentina, mediante el programa SIGEpi.

OBJECTIVES: To determine the case distribution of accidental ophidism in the Córdoba province of Argentina, identify high risk areas, and evaluate the usefulness of the SIGEpi software program (Pan American Health Organization, Washington, DC, United States of America). METHODS: Information regarding the 299 cases of accidental ophidism reported in Córdoba in 1995-2006 was collected from the Provincial Epidemiology Department's official records of incidents involving venomous creatures. The SIGEpi software program was used for geographic mapping. Specific maps were produced to identify, quantify, and visualize the danger zones and areas of high risk for ophidism. RESULTS: The incidents occurred mostly in the northern and western areas of the province. Snakes of the Bothrops genus were responsible for the majority of the incidents (87.7% of the total). The departments with the highest annual incidence rates were Pocho and Río Seco (> 10 incidents per 100,000 residents). Three ophidism high-risk zones were identified: one in far west of the province, another in the far north, and another just north of Bañados del Río Dulce and the Mar Chiquita lagoon. CONCLUSIONS: Accidental ophidism constitutes a major health problem in the Córdoba province where incidence rates are higher than those areas with more severe economic issues tied to rural labor. SIGEpi software is a reasonable choice for studying public health challenges and proved to be effective in identifying areas at high risk for ophidism.

Identificación de las zonas de riesgo ofídico en Córdoba, Argentina, mediante el programa SIGEpi / Identifying areas of high risk for ophidism in Cordoba, Argentina, using SIGEpi software

OBJETIVOS: Describir la distribución de los accidentes ofídicos en la provincia de Córdoba, Argentina, identificar las zonas de mayor riesgo y analizar la utilidad del programa informático SIGEpi. MÉTODOS: Se recopiló la información relacionada con los 299 accidentes ofídicos notificados en la provincia de Córdoba entre los años 1995 y 2006, tomados del registro oficial de la Dirección de Epidemiología provincial para accidentes por animales venenosos. Para su localización geográfica se utilizó el programa informático SIGEpi. Se generaron mapas específicos que permitieron identificar, cuantificar y visualizar las zonas vulnerables y de mayor riesgo ofídico. RESULTADOS: Los accidentes se concentraron en el sector norte y oeste de la provincia. A las serpientes del género Bothrops correspondió la mayoría de los accidentes (87,7 por ciento del total). Los departamentos con mayor incidencia anual de accidentes de este tipo fueron Pocho y Río Seco ( > 10 accidentes por 100 000 habitantes). Se identificaron tres zonas de mayor riesgo ofídico: una en el extremo oeste de la provincia, una en el extremo norte y otra al norte de Bañados del Río Dulce y la laguna Mar Chiquita. CONCLUSIONES: Los accidentes ofídicos constituyen un importante problema de salud en la provincia de Córdoba, con una incidencia superior en las zonas de mayor carencia económica vinculadas al trabajo rural. El programa SIGEpi constituye una opción adecuada para estudiar problemas de salud pública y resultó eficaz para identificar las zonas de mayor riesgo ofídico.

OBJECTIVES: To determine the case distribution of accidental ophidism in the Córdoba province of Argentina, identify high risk areas, and evaluate the usefulness of the SIGEpi software program (Pan American Health Organization, Washington, DC, United States of America). METHODS: Information regarding the 299 cases of accidental ophidism reported in Córdoba in 1995-2006 was collected from the Provincial Epidemiology Department's official records of incidents involving venomous creatures. The SIGEpi software program was used for geographic mapping. Specific maps were produced to identify, quantify, and visualize the danger zones and areas of high risk for ophidism. RESULTS: The incidents occurred mostly in the northern and western areas of the province. Snakes of the Bothrops genus were responsible for the majority of the incidents (87.7 percent of the total). The departments with the highest annual incidence rates were Pocho and Río Seco ( > 10 incidents per 100 000 residents). Three ophidism high-risk zones were identified: one in far west of the province, another in the far north, and another just north of Bañados del Río Dulce and the Mar Chiquita lagoon. CONCLUSIONS: Accidental ophidism constitutes a major health problem in the Córdoba province where incidence rates are higher than those areas with more severe economic issues tied to rural labor. SIGEpi software is a reasonable choice for studying public health challenges and proved to be effective in identifying areas at high risk for ophidism.