American bullfrog (Lithobates catesbeianus) diet in Uruguay compared with other invasive populations in Southern South America

Between 2000-2020, more than ten new populations of the invasive American bullfrog (Lithobates catesbeianus) have been reported in the southern cone of South America. We studied the stomach contents of 126 bullfrogs from a population at an early invasion stage in Uruguay (Acegua, Cerro Largo Department). We observed a rich diet, with extensive prey volume range (1 mm3 to more than 7 000 mm(3)); the most frequent items were Hymenoptera (19.6%), Coleoptera (16.4%), Amphipoda (13.3%), Anura (8.9%) and Heteroptera (8.7%). Despite some overlap, differences were observed in volume (chi(2) = 54.6, p \u3c0.001, d.f. = 2) and prey quantity (F = 8.1, p \u3c0.001, d.f. = 79) between males, females, and juveniles. Juveniles showed significantly higher consumption of terrestrial prey by count (82% of their total ingestion) than adults (29% for males and 32% for females) (chi(2) = 28.5, p \u3c0.001, d.f. = 2). Adults, especially females, showed a high frequency of cannibalism (33% of their total ingestion; chi(2) = 20.9, p \u3c0.001, d.f. = 2). Comparing our data with other bullfrog regional studies, we found great plasticity in trophic habits and differences in the incidence of cannibalism (higher incidence in the populations of Acegua, Uruguay, and Buenos Aires, Argentina). These differences could be related to local biodiversity, but also could be affected by the invasion phase. Cannibalism frequency was higher in small bullfrog populations, where it could be favoring the establishment success. This shift in foraging strategies during the invasion process had been insufficiently evaluated in amphibians. Knowing the ecological determinants for the invasion by bullfrogs can be useful to the development of management strategies

First report of four characiform fishes (Ostariophysi: Characiformes) for Uruguay

In this article the authors present the first report of four characiform fish species for Uruguay, extending their current distribution to the middle and lower Uruguay River basin: Astyanax saguazu Casciotta, Almirón and Azpelicueta, 2003; Hypobrycon poi Almirón, Casciotta, Azpelicueta and Cione, 2001; Leporinus amae Gody, 1980; Cyphocharax saladensis (Meinken, 1933). These species were previously recorded from either the upper Uruguay River, Patos-Merín lagoon system or Paraná River. Color pattern in life for A. saguazu and H. poi are described for the first time

New records of freshwater fish for Uruguay

Based on National Collections records, this article presents the first report of eight freshwater fish species for Uruguay in the middle and lower Uruguay River basin, extending their current distribution: Cyanocharax alegretensis Malabarba and Weitzman, 2003; Leporinus lacustris Amaral Campos, 1945; Microglanis aff. eurystoma Malabarba and Mahler, 1998; Tatia boemia Koch and Reis, 1996; Lepthoplosternum pectorale (Boulenger, 1895); Crenicichla missioneira Lucena and Kullander, 1992; C. minuano Lucena and Kullander, 1992; Apistogramma borellii Regan, 1906. These species were previously recorded either for upper Uruguay River or Paraná River

Variabilidad y determinantes del auto-raleo en un gremio de peces anuales

Tribunal: Dr. Marcelo Loureiro, Dra. Ana I. Borthagaray, Dr. Danilo Calliari

A new species of Gymnogeophagus Miranda Ribeiro from Uruguay (Teleostei: Cichliformes)

We describe a new species of a substrate-brooding Gymnogeophagus, based on coloration characters. The new species can be distinguished from the remaining substrate-brooding species in the genus by the unique pigmentation of the dorsal fin which consists of light blue, diagonal stripes over a red background in the spiny section and a combination of round, elliptic, and elongated bright blue spots over a red background in the soft section. It can be further distinguished from all other species of Gymnogeophagus by the following combination of characters: a discontinuous bright blue band above the upper lateral line in the humeral area, light blue roundish spots over a red to orange background on the anal fin, and conspicuous bright blue horizontal bands on body. The new species inhabits a wide range of freshwater habitats in the lower rio Uruguay basin, Rio de la Plata coastal drainages and Atlantic Ocean coastal drainages in Uruguay.Describimos una nueva especie de Gymnogeophagus con incubación de sustrato, en base a caracteres cromáticos. La nueva especie puede ser diferenciada de las restantes especies del género por la exclusiva pigmentación de la aleta dorsal, la que consiste de bandas oblicuas de color celeste sobre fondo rojo en la porción espinosa y una combinación de manchas redondas, elípticas, o alargadas azul brillantes sobre fondo rojo en la porción blanda. Además puede ser distinguida de las otras especies de Gymnogeophagus por la siguiente combinación de caracteres: banda horizontal azul iridiscente situada por encima de la línea lateral superior discontinua en la región humeral, manchas azules brillantes redondeadas sobre fondo rojo anaranjado en la aleta anal, bandas horizontales azul brillante en el cuerpo conspicuas. La nueva especie habita una amplia gama de hábitats de agua dulce en el sector inferior de la cuenca del río Uruguay, los drenajes costeros del Río de la Plata y drenajes costeros del Océano Atlántico en Uruguay

A new species of Gymnogeophagus Miranda Ribeiro from Uruguay (Teleostei: Cichliformes)

ABSTRACT We describe a new species of a substrate-brooding Gymnogeophagus , based on coloration characters. The new species can be distinguished from the remaining substrate-brooding species in the genus by the unique pigmentation of the dorsal fin which consists of light blue, diagonal stripes over a red background in the spiny section and a combination of round, elliptic, and elongated bright blue spots over a red background in the soft section. It can be further distinguished from all other species of Gymnogeophagus by the following combination of characters: a discontinuous bright blue band above the upper lateral line in the humeral area, light blue roundish spots over a red to orange background on the anal fin, and conspicuous bright blue horizontal bands on body. The new species inhabits a wide range of freshwater habitats in the lower rio Uruguay basin, Rio de la Plata coastal drainages and Atlantic Ocean coastal drainages in Uruguay

First report of four characiform fishes (Ostariophysi: Characiformes) for Uruguay

In this article the authors present the first report of four characiform fish species for Uruguay, extending their current distribution to the middle and lower Uruguay River basin: Astyanax saguazu Casciotta, Almirón and Azpelicueta, 2003; Hypobrycon poi Almirón, Casciotta, Azpelicueta and Cione, 2001; Leporinus amae Gody, 1980; Cyphocharax saladensis (Meinken, 1933). These species were previously recorded from either the upper Uruguay River, Patos-Merín lagoon system or Paraná River. Color pattern in life for A. saguazu and H. poi are described for the first time

The hidden diversity: invertebrates of temporary ponds in Barra Grande Uruguay.

Los charcos temporales de Uruguay y los invertebrados que en estos habitan representan ecosistemas relativamente poco explorados,sin referencias claras en relación a los niveles de diversidad que presentan. En el presente trabajo reportamos la presencia de 216 especies y morfoespecies de invertebrados y una estimación total de riqueza entre 263 y 373 morfoespecies, para 18 charcos temporales de la cuenca de la Laguna Castillos, en el departamento de Rocha, Uruguay. Esta diversidad permitiría mantener la estabilidad del funcionamiento del ecosistema y los servicios que este brinda como ser agua potable, forraje para el ganado, limitación en la abundancia de patógenos y brotes de enfermedades o resistencia del sistema frente a contaminantes. Los estudios ecológicos en charcos temporalesconstituyenexcelentesmodelosparaestudios de biodiversidad ya que proveen resultados generalizables a otros ecosistemas. Sin embargo, una de las limitaciones que encontramos en este trabajo fue la dificultad para la identificación taxonómica de los invertebrados. La gestión y manejo de la diversidad necesita una base taxonómica sólida que permita conocer la composición y estructura de dicha diversidad. Por lo tanto, resaltamos la importancia de realizar estudios en sistemática de invertebrados de agua dulce en Uruguay.Temporary ponds of Uruguay and the invertebrates that inhabit them represent relatively unexplored ecosystems,without clear references in relation to the diversity levels they host. In the present work we report the presence of 216 species and morphospecies of invertebrates and a total estimate of richness between 263 and 373 species, for 18 temporary ponds of Castillos Lagoon Basin, in the department of Rocha, Uruguay. This high species diversity would allow maintaining the stability of ecosystem functioning and the services it provides, such as drinking water, attenuation of hydrological pulses in lagoons and rivers, forage for livestock, limitation in the abundance of pathogens and disease outbreaks or system resistance against contaminants. Ecological studies in temporary ponds are excellent models for biodiversity studies and provide results that can be generalized too ther ecosystems. However, one of the limitations raised in this work was the difficulty for the taxonomic identification of invertebrates. The management of diversity needs a solid taxonomic base that allows knowing the composition and structure of that diversity. Therefore, we highlight the importance of systematic studies of fresh water invertebrates in Uruguay.CSIC: Grupos-657725

A new species of Austrolebias Costa (Cyprinodontiformes: Rivulidae) from northeastern Uruguay, with comments on distribution patterns

A new species of Austrolebias is described based on individuals from the middle and upper río Negro (río Uruguay basin) and río Yaguarón (Patos-Merín system). The new species can be differentiated from all other species of the genus by the unique presence in males of uniform bluish gray pigmentation on flanks (without vertical bands) and unpaired fins. The new species is also distinguished by the combination of characters associated with a reduction of the squamation of the abdominal, preopercular, and opercular regions. The new species presents some morphological characteristics similar to A. gymnoventris and A. luteoflammulatus. The distribution of the new species is concordant with three other species of Austrolebias and may represent a case of drainage rearrangement of the río Negro upstream tributaries (río Uruguay basin) and tributaries of laguna Merín system