Julián N. Lescano

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.

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.

Description of the advertisement and distress call of Chacophrys pierottii and comments on the advertisement call of Lepidobatrachus llanensis (Anura: Ceratophryidae)

Chacophrys is a monotypic genus in the family Ceratophryidae which also contains Ceratophrys and Lepidobatrachus. In this paper an analysis of the acoustic repertoire of Chacophrys pierottii is presented and compared with calls from other Ceratophryidae species. The advertisement call of Chacophrys is composed of pulsed notes with a higher dominant frequency and a marked bioacoustic differentiation with respect to Ceratophrys and Lepidobatrachus. Moreover, new contributions to the bioacoustical knowledge of Lepidobatrachus llanensis are reported.

New records of the Endangered Chacoan peccary Catagonus wagneri suggest a broader distribution than formerly known

The Chacoan peccary Catagonus wagneri is the rarest and most threatened of the three extant species of peccary. Its presence has been recorded in the northern Dry Chaco ecoregion, which spans northern Argentina, western Paraguay and south-eastern Bolivia. However, distribution models based on its occurrence in Argentina have predicted that suitable habitat extends southwards into central Argentina, where the species was not previously recorded. We present several records of the species outside the currently accepted distribution, including the first two records in the west of Cordoba province, > 650 km south of the southern limit of the previously known distribution. The discovery of the Chacoan peccary in central Argentina could serve as a justification for the protection of Chacoan forests in this region, where deforestation rates are among the highest worldwide.

Anfibios de las Sierras Pampeanas Centrales de Argentina: diversidad y distribución altitudinal

Las Sierras Pampeanas Centrales (SPC) ocupan parte del territorio de las provincias de Cordoba y San Luis (Argentina) y constituyen un area de singular importancia biogeografica. En este trabajo se presenta una sintesis sobre el conocimiento de la diversidad y distribucion altitudinal de la fauna de anuros de las Sierras de Cordoba y San Luis. El listado de especies de anfibios de las SPC se compilo utilizando diversas fuentes de informacion (datos de campo, colecciones biologicas y registros bibliograficos). Utilizando esta informacion se caracterizo el rango de distribucion altitudinal de cada especie y se analizaron las asociaciones entre la riqueza y composicion de anfibios y el gradiente de altura de las SPC. Se registro un total de 22 especies de anfibios pertenecientes a cinco familias. Dicha fauna se distribuye de forma heterogenea en el gradiente de altura de las SPC observandose una disminucion lineal de la riqueza en funcion de la altura y ensambles asociados a sectores altitudinales definidos. Los resultados obtenidos representan informacion basica y necesaria para evaluar el impacto de diversas actividades humanas en este particular y fragil sistema de montana

Natural interspecific hybridization in Odontophrynus (Anura: Cycloramphidae)

The frog genus Odontophrynus is a composite of diploid and tetraploid populations and species that are widely distributed in South America. Some of the several genetic studies on this group report the production of artificial hybrids but only a single case of natural hybridization has been documented, in southern Brazil. In this study we report the finding of an interspecific natural hybrid specimen in central Argentina. We present morphological and cytogenetical evidence that the diploid taxa Odontophrynus cordobae and O. occidentalis are the parental species. The hybrid genome exhibited problematic pairing and segregation of homeologue chromosomes during meiosis, and the production of non-reduced gametes.

New data on the endangered Chacoan peccary (Catagonus wagneri) link the core distribution with its recently discovered southern population

Abstract The endangered Chacoan peccary (Catagonus wagneri Rusconi, 1930) has been recorded in western Paraguay, southeastern Bolivia and northern Argentina, reaching the north of Santiago del Estero province. Recently, however, this species was found much further south in central Argentina, ca. 650 km away from the southern limit of its known distribution. In this report we provide new records in previously unsurveyed areas linking the core range with the southern population, suggesting a continuous distribution. Due to synergistic effects of hunting pressure and deforestation, we are almost certain that the Chacoan peccary is as threatened in central Argentina as in the rest of its distribution range.

Stereotyped Defensive Behaviours in Frogs of the Genus Odontophrynus (Amphibia: Anura: Odontophrynidae)

Abstract: Observations on stereotyped defensive behaviours are presented for 7 frog species of the Neotropical genus Odontophrynus from Argentina and Uruguay. Seven stereotyped postures were observed, among which the most common observed were puffing up the body, contracting, and crouching down. Newly reported behaviours include tongue protrusion, eye protection, and some combinations of postures. We provide an account of defensive behaviours already described in Odontophrynus and discuss the correspondence between the terminology used by previous authors and recently proposed classifications. In addition, we highlight defensive mechanisms associated with the body raising posture in Neotropical anurans, which may include intimidating predators, body shape disruption, warning signaling, and exposure of skin macroglands.