Gerardo C. Leynaud

Morphology, phylogeny and taxonomy of South American bothropoid pitvipers (Serpentes, Viperidae)

Carrasco, P.A., Mattoni, C.I., Leynaud, G.C. & Scrocchi, G.J. (2012). Morphology, phylogeny and taxonomy of South American bothropoid pitvipers (Serpentes, Viperidae). —Zoologica Scripta, 41, 109–124.

Identificación de las zonas de riesgo ofídico en Córdoba, Argentina, mediante el programa SIGEpi

OBJETIVOS: Describir la distribucion de los accidentes ofidicos en la provincia de Cordoba, Argentina, identificar las zonas de mayor riesgo y analizar la utilidad del programa informatico SIGEpi. METODOS: Se recopilo la informacion relacionada con los 299 accidentes ofidicos notificados en la provincia de Cordoba entre los anos 1995 y 2006, tomados del registro oficial de la Direccion de Epidemiologia provincial para accidentes por animales venenosos. Para su localizacion geografica se utilizo el programa informatico SIGEpi. Se generaron mapas especificos que permitieron identificar, cuantificar y visualizar las zonas vulnerables y de mayor riesgo ofidico. RESULTADOS: Los accidentes se concentraron en el sector norte y oeste de la provincia. A las serpientes del genero Bothrops correspondio la mayoria de los accidentes (87,7% del total). Los departamentos con mayor incidencia anual de accidentes de este tipo fueron Pocho y Rio Seco ( > 10 accidentes por 100 000 habitantes). Se identificaron tres zonas de mayor riesgo ofidico: una en el extremo oeste de la provincia, una en el extremo norte y otra al norte de Banados del Rio Dulce y la laguna Mar Chiquita. CONCLUSIONES: Los accidentes ofidicos constituyen un importante problema de salud en la provincia de Cordoba, con una incidencia superior en las zonas de mayor carencia economica vinculadas al trabajo rural. El programa SIGEpi constituye una opcion adecuada para estudiar problemas de salud publica y resulto eficaz para identificar las zonas de mayor riesgo ofidico.

Predation on snakes of Argentina: Effects of coloration and ring pattern on coral and false coral snakes

The occurrence of coral snake coloration among unrelated venomous and non‐venomous snake species has often been explained in terms of warning coloration and mimicry. In Argentina, no field tests have been conducted to confirm this mimetic association between one venomous coral species (Micrurus phyrrocryptus, Elapidae) and two non‐venomous snake species with a similar color pattern (Lystrophis pulcher and Oxyrhopus rhombifer, Colubridae). The aims of this work were to test for the possible aposematic or cryptic function of the ring pattern and coloration of coral snakes and false coral snakes from central Argentina, and to analyse whether the pattern is effective throughout the year. Predation on snakes was estimated by using non‐toxic plasticine replicas of ringed venomous and non‐venomous snakes and unbanded green snakes placed along transects in their natural habitat during the dry and rainy season. Ringed color pattern was attacked by predators despite the background color. One of the replica types was attacked more than expected during the dry season, suggesting that both shape and width of rings may influence the choice by predators. The reaction of predators towards replicas that mimic snake species with ringed patterns is independent of the geographical region, and we can conclude that mimicry characteristics are quite general when the true models are present in the area.

American bullfrog invasion in Argentina: where should we take urgent measures?

Argentina is the country with the most geographically extended biological invasion of the American bullfrog (Lithobates catesbeianus) in South America after Brazil. Here, we used a maximum entropy ecological niche modeling algorithm (using records of the native range of American bullfrog) to project the model onto the whole of Argentina. We determined the most suitable habitats for this invasive alien species and where we consider urgent measures should be taken. Our projections showed good agreement with known feral populations of American bullfrog in Argentina. By implementing the “Multivariate Environmental Similarity Surface” analysis, we be able to determine that factors such as low precipitations or highest altitudes could be limiting the species’ ability to invade the west and south of the country. We suggest that strategies should focus on detecting established feral populations of the American bullfrog and preventing further introductions or range expansion of feral populations in the northeast portion of the country. Lastly, we report a new feral population of bullfrogs in Argentina.

Density, population structure and activity pattern of Hydromedusa tectifera (Testudines-Chelidae) in a mountain stream of Córdoba province, Argentina

The Snake-necked Turtle ( Hydromedusa tectifera ) is mainly distributed in the northeastern provinces of Argentina; however, some isolated populations occur in central Cordoba. This is the first report on some ecological aspects of one of these populations. Population density and annual activity pattern were characterized at Toro Muerto Stream in the Sierras region of the Cordoba province, central Argentina. Turtles were hand-captured and sex and carapace length were determined for each individual. Mark-recapture data were used to estimate population density, variation in monthly capture rates, and sex ratios throughout the sampling months. A total of 96 turtles were captured and density was estimated at 218 individuals ha −1 . Individuals were captured all year round, but showed activity peaks in spring and summer. This seasonal pattern has also been observed in other freshwater turtles. During the mating season a higher number of males were captured, which suggested a seasonal difference in activity patterns between sexes.

Breeding-site selection by red-belly toads, Melanophryniscus stelzneri (Anura: Bufonidae), in Sierras of Córdoba, Argentina

Differences among wetlands can have important consequences on reproductive success of amphibians; therefore habitat selection is expected to be of particular importance for anurans inhabiting heterogeneous environments. To investigate if the red-belly toad ( Melanophryniscus stelzneri ; Anura: Bufonidae) uses available habitats differentially and to determine the main factors influencing the use of certain water bodies as breeding habitat, we surveyed 30 spawning sites used by red-belly toads, and 30 adjacent unused sites, in an area of the Sierras of Cordoba, Argentina. We evaluated the relative importance of morphological and biotic features of ponds, and the presence of other organisms within the water body on the use of ponds as breeding sites by red-belly toads. Eight habitat variables related to important water body features were recorded and were used to fit a habitat selection model with GLM. Red-belly toads presented a positive selection to mallines , a wetland characteristic of the Sierras of Cordoba. They were associated with small, shallow ephemeral ponds with muddy banks and a high percent of vegetation cover. In general, the ponds used did not host other anuran species or potential predators. Breeding site selection by red-belly toads is largely consistent with records for other species of the genus in other parts of Argentina.

Biogeographic regions of Central Argentina based on snake distribution: evaluating two different methodological approaches

Regionalization studies attempt to divide an area into regions by studying the distribution of its biota. Here we used snake distribution in Central Argentina to recognize distribution patterns, and then compared two methods (cluster analysis and endemism analysis) and the patterns found with previously defined regions. Both analyses recovered Chaco and, within Chaco, the subregion Chaco Serrano, as well as all the snake species that are threatened or range-restricted occurring only in the Chaco region, which has been severely deforested in the last decades. The Espinal region was not recovered by cluster analysis or NDM software, and may be considered an “impoverished” Chaco or a transition zone. The Pampas was only recovered by cluster analysis. NDM appears to be more robust than cluster analysis, whereas the latter seems to be very sensitive to sampling problems, sometimes identifying spurious areas or areas characterized by having no exclusive species.

Redescription of the southernmost snake species, Bothrops ammodytoides (Serpentes: Viperidae: Crotalinae)

Bothrops ammodytoides is a pitviper species endemic to Argentina that inhabits arid and semiarid areas from sea level to more than 3000 m, reaching the southernmost latitude for snakes. According to previous studies, the species is placed in the Bothrops alternatus group. We redescribe Bothrops ammodytoides based on examination of 101 specimens and provide new data on lepidosis, hemipenial morphology, cranial osteology, variation in coloration, and distribution. We compare Bothrops ammodytoides with representative species of the genus and related genera. Morphological comparisons reveal considerable affinities between Bothrops ammodytoides, Bothrops pictus, Bothrops andianus ,a ndBothrocophias microphthalmus, suggesting that the current taxonomy for Bothrops ammodytoides requires to be reassessed.

Diet of Hydromedusa tectifera (Testudines-Chelidae) in a mountain stream of Córdoba province, Argentina

The diet of Hydromedusa tectifera occurring in two mountain streams in the province of Cordoba is described through a comparative analysis of 154 individuals. Turtles were manually captured between August 2005 and August 2006 from streams at the localities of Tanti and Flor Serrana. Before being released, turtles were stomach-flushed, and sex and carapace length were recorded. The stomach contents were observed under stereomicroscope; prey items were identified and classified according to size and volume. The importance of the different items was quantified using the Index of Relative Importance (IRI). Similarity in the diet between sexes and among size classes and seasons of an annual cycle was evaluated using the simplified Morisita index. Trophic breadth was estimated with the Shannon diversity index. Detrended Correspondence Analysis (DCA) was used to evaluate differences in the diet between categories (sex, size classes). Forty-seven food items belonging to the following taxa were identified: leeches, annelids, gastropods, arachnids, insects, and fishes. According to the IRI value, the most important items in the diet of H. tectifera were larvae of Trichoptera (IRI = 33.5), fishes (IRI = 30), and naiads of Odonata (IRI = 25.2). The relative importance of the items varied with size of turtles but not with sex. Size of prey consumed increased with increasing turtle size. A greater trophic breadth was observed in smaller individuals.

Annual activity patterns of snakes from central Argentina (Córdoba province)

Annual variations of activities of 13 snake species from the province of Córdoba, Argentina, are described based on the analysis of 6838 records of arrivals to the serpentarium of Centro de Zoología Aplicada (Córdoba, Argentina) between 1973 and 2000. The climate in the region is semiarid with mean annual rainfall of 650 mm concentrated in summer and mean annual temperature of 16°C. The species analyzed are Boa constrictor occidentalis, Bothrops alternatus, B. ammodytoides, B. diporus, Crotalus durissus terrificus, Epicrates cenchria alvarezi, Liophis poecilogyrus sublineatus, Lystrophis dorbignyi, L. pulcher, Philodryas baroni, P. patagoniensis, Micrurus pyrrhocryptus, and Waglerophis merremii. All species showed a similar activity pattern, with a maximum in the warm and wet season and a minimum in the dry and cold season. The following subgroups can be observed: (1) unimodal, with a peak in spring, associated with species related to aquatic riparian environments and a diet based on amphibians; (2) bimodal, related to species of mountain areas and with great daily and seasonal fluctuations in temperature; and (3) unimodal, with peak in autumn, related to species from the Chaco, of dry forest environments and a diet based on rodents. The degree of seasonal activity of the species studied is halfway between low values found in tropical forests and high values characteristic of desert areas.