Laura C. Pereyra

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.

Variation of thermal parameters in two different color morphs of a diurnal poison toad, Melanophryniscus rubriventris (Anura: Bufonidae)

We study the variation in thermal parameters in two contrasting populations Yungas Redbelly Toads (Melanophryniscus rubriventris) with different discrete color phenotypes comparing field body temperatures, critical thermal maximum and heating rates. We found significant differences in field body temperatures of the different morphs. Temperatures were higher in toads with a high extent of dorsal melanization. No variation was registered in operative temperatures between the study locations at the moment of capture and processing. Critical thermal maximum of toads was positively related with the extent of dorsal melanization. Furthermore, we founded significant differences in heating rates between morphs, where individuals with a high extent of dorsal melanization showed greater heating rates than toads with lower dorsal melanization. The color pattern-thermal parameter relationship observed may influence the activity patterns and body size of individuals. Body temperature is a modulator of physiological and behavioral functions in amphibians, influencing daily and seasonal activity, locomotor performance, digestion rate and growth rate. It is possible that some growth constraints may arise due to the relationship of color pattern-metabolism allowing different morphs to attain similar sizes at different locations instead of body-size clines.

The use of ephemeral reproductive sites by the explosive breeding toad Melanophryniscus rubriventris (Anura: Bufonidae): is it a predator cue mediated behavior?

Amphibians detect quality signals when selecting reproduction sites. We hypothesize that Melanophryniscus rubriventris, an explosive breeding toad that reproduces in small, ephemeral water bodies, is able to select sites without predators. We performed a field experiment simulating oviposition sites, two with predators (tadpoles and bugs) and one control. Contrary to our expectations, we obtained no differences in the number of eggs deposited. We also performed an experiment to test the capability of M. rubriventris tadpoles to detect potential predators. Tadpoles could not detect predators, as other species did. Melanophryniscus rubriventris is selecting spawning sites following other signals, not predation risk. Identifying selection cues is crucial to protect species that depend on threatened habitats.

Patterns of daily and seasonal calling activity of a direct-developing frog of the subtropical Andean forests of Argentina

Climate often regulates different aspects of the life cycle and activity of amphibians. Climatic seasonality may impose severe restrictions on breeding patterns of direct-developing terraranan frogs. We studied the influence of abiotic cues on calling activity of males of the direct-developing frog Oreobates discoidalis in the Yungas forests of north-western Argentina. Vocalization activity and daily emission pattern of the vocal repertoire were registered with a frog-logger, and climatic variables were registered with a data logger. We sampled two reproductive seasons from 2010 to 2011. We used ordinal logistic regression to evaluate the relationship between independent climatic variables and the intensity of calling activity. The calling season of males of O. discoidalis was triggered by the first rainfall of the aestival season. The species could be defined as crepuscular–nocturnal with a calling activity peak at dusk. Sporadic calling activity during day time was associated with conditions of high humidity and rainfall. Both the emission and the intensity of the advertisement call activity were influenced by time of the day, high levels of relative air humidity and presence of rainfall; air temperature was not a determinant factor in the calling activity of this frog species. Territorial calls were strongly associated with full chorus activity that could be associated with a mechanism of inter-male spacing.

Figure 1 In A New Species Of Elachistocleis (Anura: Microhylidae) From North-Western Argentina

FIGURE 1. Elachistocleis haroi sp. nov., holotype (FML 24900), dorsal and ventral views of body, and head profile. White bar 1 cm.