Mauricio Sebastián Akmentins

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.

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.

Vocal repertoire of two species of Oreobates Jiménez de la Espada, 1872 (Anura: Strabomantidae) of the Yungas Andean Forest, NW Argentina

The vocal repertoire of males of two cryptic species of Oreobates and interpretation of the communicative significance of vocalizations were studied under natural conditions in Yungas Andean Forest of NW Argentina. Males of O. discoidalis and O. barituensis showed remarkable territorial behaviour defending their calling sites against conspecific males through both aggressive vocalizations and fights involving physical contact. The vocal repertoire of both species consists of at least three different call types. Two of these vocalizations, advertisement calls and territorial calls were utilized in long-range territorial interactions, and aggressive calls were utilized in close-range male-male territorial interactions. This represents the first report of a complex repertoire of vocalizations in the genus Oreobates

Amphibia, Anura, Strabomantidae, Oreobates barituensis : distribution extension, new provincial record and geographic distribution map

Oreobates barituensis Vaira and Ferrari, 2008 (Figure 1) is the most recently described of 16 recognized species of the genus Oreobates Jimenez de la Espada, 1872 (Frost 2009). The genus occurs in western South America from southern Colombia to southwestern Brazil and northwestern Argentina (Hedges et al. 2008). The two Argentinean species of Oreobates (O. discodalis and O. barituensis) inhabit subtropical humid montane forests belonging to the ecoregion of Southern Andean Yungas (Vaira and Ferrari 2008). Oreobates barituensis is currently known only from three close localities (the most distant was separated about 10 km straight-line) in northern Salta province, Argentina, and its possible occurrence in adjacent Bolivia has been discussed (Vaira and Ferrari 2008).

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.

Composición y riqueza de anfibios y sus relaciones con las características de los sitios de reproducción en un sector de la Selva Atlántica de Misiones, Argentina

Atlantic forest harbors a large number of endemic amphibian’s species. At present only 7.5 % of the Atlantic Forest original surface remains. In this study we compare frog’s species richness and assemblage composition between different types of reproductive habitats in a sector of the Atlantic Forest of Argentina. Surveys were made during four months in two consecutive years. Four reproductive habitats were surveyed: temporary ponds, pig wallows, temporary streams and permanent streams. Frogs species richness and composition and environmental descriptors were recorded in these habitats. Temporary ponds have the greatest richness. Anuran abundance shows associations with vegetation in the bodies of water. The results suggest that different types of wetlands exert differential pressures (e.g. predation, hidroperiod) on amphibian assemblages. Finally, we highlight the importance of small ponds and vegetation heterogeneity for anuran assemblages of the Atlantic Forest of Argentina.

Registro de un ejemplar de Trachemys scripta elegans (Wied 1839) en la provincia de Jujuy, Argentina

Localidad Republica Argentina, provincia de Jujuy, departamento El Carmen, ruta nacional N° 9 (24°26’6.77”S; 65°17’59.86”W; altitud: 1252 m s.n.m). Colectores M. S. Akmentins, M. F. Quiroga y N. Gonzalez. Ejemplar hembra adulto hallado termorregulando sobre la carpeta asfaltica a las 17:30 hs del dia 01 de junio de 2015. El ejemplar fue removido del ambiente natural y se mantiene en cautividad.

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.

Reptilia, Squamata, Dipsadidae, Tomodon orestes Harvey and Muñoz, 2004: distribution extension, new country record

We report the first record of Tomodon orestes Harvey and Munoz, 2004 for Argentina. An adult male was collected in November 2008 in an open grassland habitat in the locality of Vallecito, Santa Victoria department, Salta province, Argentina. This new record is the southernmost locality for the species extending its distribution range ca. 95 km straight-line south from type locality.