This paper describes ecological features of the reproductive biology of a population of Elachistocleis bicolor from Uruguay. From a monthly sample obtained throughout a year, we measured mass of the fat bodies and the ovaries, testicular volume, and estimate fecundity. We found evidence of a relationship between reproductive activity and air temperature, although we cannot rule out photoperiod as a regulator mechanism of the reproductive cycle. The dynamics of fat bodies are independent of the reproductive cycle, since their mass does not vary significantly along the year. We found evidence of sexual dimorphism and dichromatism, expressed by females being largest than males and by dark colored vocal sacs of males, although only present in some of them. Fecundity in females increases with body size, however larger females do not invested most of resources in reproduction.

Este trabajo describe aspectos de la biología reproductiva de una población uruguaya de Elachistocleis bicolor. En una muestra mensual obtenida durante un año, se midió la masa de los cuerpos grasos y ovarios, el volumen testicular y se estimó la fecundidad. Se encontró evidencia que la actividad reproductiva se encuentra correlacionada con la temperatura, sin embargo no podemos descartar al fotoperiodo como regulador del ciclo reproductivo. La dinámica de los cuerpos grasos es independiente del ciclo reproductivo, ya que su masa no varió significativamente durante el año. Se encontró evidencia de dimorfismo y dicromatismo sexual, expresado por el mayor tamaño de las hembras y en la coloración oscura del saco vocal de los machos, aunque sólo presente en algunos de ellos. La fecundidad de las hembras se incrementó con el tamaño corporal; sin embargo, las hembras más grandes no invierten una mayor proporción de sus recursos en la reproducción.

Climate change (CC) constitutes one of the main biodiversity threats. The efects of CC on species are apparent worldwide, with primarily poleward and upward shifts in species distribution. Due to their narrow distribution, threatened species are highly vulnerable to CC. In this context, protected areas (PA) could be key tools for adaptation to CC. Our aims were to study the efects of CC on the distribution and richness of the threatened and near threatened amphibians of Uruguay; and to evaluate the efectiveness of the National Network of Protected Areas (NNPA) at present and under future climate scenarios. To model the distribution of nine species, we obtained records from herpetological collections, scientifc publications and GBIF, as well as current data and future climate projections of the General Circulation Model HadCM3 under the A2 and B2 IPCC scenarios from Worldclim. To model species distribution we applied maximum entropy techniques (MAXENT). To evaluate the efectiveness of NNPA we conducted a gap analysis by overlaying PA with the distribution of species. The models indicate that the distribution of most amphibian species could expand in Uruguay in the future; except for Pleurodema bibroni y Melanophryniscus montevidensis. Local amphibian richness is predicted to increase, mainly in the northwest and east of the country. While amphibians studied are included in at least one PA, less than 2% of the distribution is actually covered by the NNPA, both currently and under CC scenarios; which it is a strong indicator of the inefciency of the system. Although projected CC for this region would not constitute a major threat to amphibians studied, the scarce protection by the NNPA represents a risk to the conservation of herpetofauna facing the other components of global change.

El cambio climático (CC) es una de las principales amenazas a la biodiversidad. Se han constatado efectos del CC sobre la distribución de las especies, principalmente corrimientos hacia latitudes altas y zonas elevadas. Las especies amenazadas resultan especialmente vulnerables a dichos cambios. En este marco, las áreas protegidas (AP) podrían ser una herramienta clave para la adaptación al cambio climático. Nuestros objetivos son: estudiar los efectos del CC sobre la distribución y riqueza de anfibios amenazados y casi amenazados de Uruguay, y evaluar la eficacia del Sistema Nacional de Áreas Protegidas (SNAP) en el presente y ante escenarios de CC. Para modelar la distribución de nueve especies se obtuvieron registros de colecciones herpetológicas, publicaciones científicas y del GBIF, datos de clima actual y proyecciones del Modelo de Circulación General HadCM3 bajo los escenarios A2 y B2 del IPCC descargadas del Worldclim. La distribución potencial se obtuvo aplicando modelos de máxima entropía (MAXENT). Para evaluar la eficacia del SNAP se realizó un análisis de vacíos, superponiendo la cobertura de las AP con la distribución de las especies. Los modelos indican que la mayoría de las especies expandirá su distribución a futuro en Uruguay, excepto Pleurodema bibroni y Melanophryniscus montevidensis. La riqueza local de anfibios podría aumentar en el noroeste y este del país. Si bien los anfibios estudiados están incluidos al menos en un área del SNAP, la superfcie protegida cubre menos de 2% de la distribución de las especies, tanto en la actualidad como bajo los escenarios de CC. Esto indica la baja eficacia del sistema. Si bien el CC esperado para la región no sería una amenaza para los anfibios estudiados, la escasa protección por parte del SNAP representa un riesgo para la conservación de la herpetofauna nativa frente a otros componentes del cambio global.

A distribuição espacial e temporal de Pseudis minuta Günther, 1858 e fatores ambientais relacionados à atividade reprodutiva da espécie foram estudados na Reserva Biológica do Lami (30º 15' S; 51º 05' W), Porto Alegre, Brasil. As atividades de campo compreenderam visitas bimensais a três banhados semi-permanentes, com duração aproximada de dois dias e duas noites cada, entre agosto de 2004 e julho de 2005. Observaram-se diferenças nos sítios utilizados por machos, fêmeas e juvenis, com machos ocupando locais mais profundos e mais distantes da margem. A distribuição temporal dos indivíduos, vocalizações e amplexos indicaram que a atividade reprodutiva de P. minuta está relacionada com alguns dos fatores abióticos estudados. Os machos em atividade de vocalização apresentaram diferença significativa em relação aos machos não vocalizantes para todos os fatores abióticos diários analisados (temperatura do ar, temperatura da água, umidade relativa do ar e pluviosidade), bem como na temperatura do ar e pluviosidade mensais. O número de machos, fêmeas e juvenis em atividade foi influenciada por pelo menos um dos fatores ambientais mensais ou diários analisados. Conclui-se que a reprodução desta espécie é sazonal e parcialmente determinada por fatores abióticos.

We studied the reproductive biology of a population of Pseudis minuta Günther, 1858 from Reserva Biológica do Lami (30º 15' S; 51º 05' W), Porto Alegre, southern Brazil. We assessed the spatial and temporal distribution of individuals (males, females, juveniles) and explored potential relationships with environmental variables. Field activities encompassed bimonthly surveys in three semi-permanent ponds, each one during approximately two days and two nights, from August 2004 to July 2005. We recorded differences in the sites used by males, females and juveniles, with males occupying deeper and more distant places from the border. The temporal distributions of individuals, calling sites and amplectant pairs indicated that the reproductive activity of P. minuta is related to some of the studied abiotic factors. Calling males presented statistical differences in relation to non-calling males for all daily abiotic variables analyzed (air temperature, water temperature, relative humidity and rainfall), as well as to monthly temperature and rainfall. The number of active males, females and juveniles was influenced by at least one of the daily or monthly environmental variables analyzed. We conclude that the reproduction in this species is seasonal and may be partially determined by abiotic factors.

The native species of amphibians and reptiles of Uruguay were categorized according to the IUCN Red List criteria. Out of 47 amphibian species, seven are listed as Critically Endangered (CR), five as Endangered (EN), one as Vulnerable (VU), three as Near Threatened (NT), and two as Data Deficient (DD); the remaining species are considered to be Least Concern (LC). Among the 64 species of reptiles evaluated, one is listed as Critically Endangered (CR), seven as Endangered (EN), two as Vulnerable (VU), one as Near Threatened (NT) and seven as Data Deficient (DD); the rest are considered to be Least Concern (LC). The use of these results as an additional criterion in the definition of protected areas in Uruguay will contribute towards the conservation of the aforementioned threatened species and their associated ecosystems.

Las especies nativas de anfibios y reptiles de Uruguay fueron categorizadas de acuerdo a los criterios de la Lista Roja de UICN. De las 47 especies de anfibios, siete se encuentran En Peligro Crítico (CR), cinco En Peligro (EN), una Vulnerable (VU), tres Casi Amenazadas (NT), y dos con Datos Deficientes (DD); las especies restantes son consideradas como Preocupación Menor (LC). Entre las 64 especies de reptiles evaluados, una se encuentra en Peligro Crítico (CR), siete En Peligro (EN), dos como Vulnerables (VU), una Casi Amenazadas (NT) y siete con Datos Deficientes (DD); las especies restantes son consideradas como Preocupación Menor (LC). El uso de estos resultados como un criterio adicional en la definición de áreas protegidas en Uruguay contribuirá hacia la conservación de dichas especies amenazadas y sus ecosistemas asociados.

A new species of bufonid toad of the genus Melanophryniscus from northern Uruguay is described. It is included in the M. moreirae group and its external morphology is similar to Melanophryniscus sanmartini. Melanophryniscus sp. nov. is distinguished by having a light brown dorsal coloration with six darker longitudinal glandular ridges on the dorsal surface of the body and the gular region uniformly black.

Se describe una nueva especie de anuro bufónido del género Melanophryniscus, procedente del norte de Uruguay. La nueva especie se incluye en el grupo M. moreirae y es similar, en cuanto a su morfología externa, con Melanophryniscus sanmartini. Melanophryniscus sp. nov. se distingue por presentar una coloración dorsal castaño clara con seis cordones glandulares longitudinales más oscuros en la superficie dorsal del cuerpo y la región gular de color negro uniforme.

Physalaemus henselii (Peters, 1872) is a little known leiuperid frog that has not been studied since the 1960’s. Herein, we redescribe its advertisement call, and assess the female sexual cycle and the reproductive period on the basis of the macroscopic analysis of the ovaries and field observations. The Ovarian Size Factor (OSF) was calculated. The study was made in Departamento de Rivera, northern Uruguay. The advertisement call consists of short (177 ± 21ms), multipulsed (20 ± 3 pulses/note) notes, with a note repetition rate of 1.57 ± 0.13 notes/s. Physalaemus henselii has a female sexual cycle with unimodal distribution of gravid females, which are present from February to September. The OSF and the ratio "females with mature oocytes / females without mature oocytes" reached the highest values from April to June. The number and size of oocytes were positively correlated with female size. The smallest female (SVL =18.94mm, weight =0.78g) with mature oocytes was found in July. The observed sexual cycle with a single annual reproductive period during the cold season (autumn and early winter), is an uncommon fact for anuran species in the region.

Physalaemus henselii (Peters, 1872) es un pequeño leiupérido que no ha sido estudiado desde los años 60. Aquí redescribimos su canto de anuncio, y determinamos su ciclo sexual femenino y el período reproductivo en base al análisis macroscópico de los ovarios y de observaciones de campo. Fue calculado el Factor de Tamaño Ovárico (FTO). El estudio fue realizado en el Departamento de Rivera, norte de Uruguay. El canto nupcial consiste en notas cortas (177 ± 21ms) y multipulsadas (20 ± 3 pulsos/nota), con una tasa de repetición de notas de 1.57 ± 0.13 notas/s. Physalaemus henselii tiene un ciclo sexual femenino con distribución unimodal de hembras maduras, las que están presentes de Febrero a Setiembre. El FTO y la tasa "hembras con ovocitos maduros / hembras sin ovocitos maduros" alcanzó los valores más altos desde Abril a Junio. El número y tamaño de los ovocitos estuvieron correlacionados positivamente con el tamaño de las hembras. La hembra más pequeña (SVL =18.94mm, masa =0.78g) con ovocitos maduros fue encontrada en Julio. El ciclo sexual observado, con un solo periodo reproductivo anual durante la estación fría (otoño e invierno temprano), constituye un hecho poco frecuente en las especies de anuros de la región.

Chaunus achavali, uma espécie de bufonídeo recentemente descrita e conhecida apenas para o Uruguai, é registrada para o Brasil. Esta espécie é morfologicamente similar a C. ictericus e C. arenarum, sendo que vários espécimes foram rotulados com esses nomes em coleções científicas brasileiras. É designado um lectótipo para C. arenarum. São apresentadas notas de campo sobre C. achavali e uma chave para identificação das espécies do grupo C. marinus.

The bufonid toad Chaunus achavali, a recently described species known only from Uruguay, is recorded for Brazil. This species is morphologically similar to C. ictericus and C. arenarum, and several individuals were labeled in Brazilian scientific collections under these taxa. A lectotype of C. arenarum is designated. Additional field notes on C. achavali and a key for the identification of the species in the Chaunus marinus group are presented.

The diet of Leptodactylus ocellatus (L., 1758) was studied in specimens collected at Maldonado Department (Uruguay), where monthly surveys were made between August 1998 and March 2000. A total of 143 frogs were collected, measured, sexed, and dissected, to assess stomach contents. The anurans were grouped into three age classes and four categories (considering sex and capture date). The trophic amplitude for each age class and sex-season category was quantified using Shannon-Weaver Index, and the trophic niche overlap between ages and categories by using the Pianka Index. Comparisons among treatments were made by G-tests. The most important prey items were coleopterans (IRI = 2547), and significant correlations were found between predator and prey sizes. The major differences on diet composition were found between extreme age classes (froglets and adults). Significant differences were also detected between sexes in the cold season but not in the warm season. Any of these changes in diet may be related with the availability of prey.