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The food habits of the Broad-snouted Caiman (Caiman latirostris) were studied in northwestern Uruguay. The most common prey were insects, the shrimp Pseudopalaemon bouvieri, the snail Pomacea canaliculata, fish and birds. Spiders, crabs, amphibians, snakes, turtles and mammals were consumed less frequently. Arthropods were the most frequent prey for juvenile caiman. Fish and snails were consumed by all size classes. The proportion of stomach contents with invertebrates decreased with increasing caiman size, and that with vertebrates was greater in the diet of larger caiman. Diet composition and ontogenetic shift are similar to that of other crocodilians considered as opportunistic generalist predators. Se estudiaron los habitos alimenticios del Yacare (Caiman latirostris) en el noroeste de Uruguay. Las presas mas comunes fueron insectos, el camaron Pseudopalaemon bouvieri, el caracol Pomacea canaliculata, peces y aves. Aranas, cangrejos, anfibios, serpientes, tortugas y mamiferos fueron consumidos menos frecuentemente. Los artropodos fueron las presas mas frecuentes de juveniles. Peces y aves fueron consumidos por todos los tamanos. La proporcion de contenidos estomacales con invertebrados disminuyo al aumentar el tamano de los caimanes, y la de vertebrados fue mayor en los individuos de mayor tamano. La composicion y cambio ontogenetico en la dieta resultan similares a los de crocodilianos considerados predadores generalistas oportunistas. [ABSTRACT FROM AUTHOR]

The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) causes chytridiomycosis, a disease among the main causes of amphibian declines worldwide. However, Bd studies on Neotropical amphibians from temperate areas are scarce. We present a comprehensive survey of Bd in Uruguay, in temperate central eastern South America, carried out between 2006 and 2014. Skin swabs of 535 specimens of 21 native and exotic frogs were tested by PCR. We used individual-level data to examine the relationship between infection, climatic variables, and their effects on body condition and the number of prey items found in stomach contents. Infection was widespread in free-ranging anurans with an overall prevalence of 41.9%, detected in 15 native species, wild American bullfrogs Aquarana catesbeiana, and captive specimens of Ceratophrys ornata and Xenopus laevis. Three haplotypes of the Bd ITS region were identified in native amphibians, all belonging to the global panzootic lineage (BdGPL), of which only one was present in exotic hosts. Despite high infection frequencies in different anurans, we found no evidence of morbidity or mortality attributable to chytridiomycosis, and we observed no discernible impact on body condition or consumed prey. Climatic conditions at the time of our surveys suggested that the chance of infection is associated with monthly mean temperature, mean humidity, and total precipitation. Temperatures below 21°C combined with moderate humidity and pronounced rainfall may increase the likelihood of infection. Multiple haplotypes of BdGPL combined with high frequencies of infection suggest an enzootic pattern in native species, underscoring the need for continued monitoring.

Histology is often underappreciated for the detection of the amphibian pathogenic fungus Batrachochytrium dendrobatidis, the cause of the potentially lethal skin disease chytridiomycosis. We evaluated the sensitivity of histology to detect chytrids in 20 wild specimens of 2 frog species from Uruguay that were clinically normal, but confirmed by PCR to be infected by B. dendrobatidis. We detected maturing and sporulated sporangia in 15 of 20 (75%) frogs, which is more sensitive than previously reported for histology. The effort needed to identify chytrids in histologic skin sections of Physalaemus henselii and Pleurodema bibroni required examination of 3.2 and 8.7 mm of skin sections for each frog species, respectively.

The main goal of this manuscript is the reevaluation of the taxonomic status of the teiid lizard Contomastix charrua, known only from Cabo Polonio, a small coastal rocky outcrop in southeastern Uruguay. This species was erected on the basis of the presence of a second pair of ceratobranchials and longer cornua in the hyoid bone, in addition to a reduced expression of the pattern of coloration as compared with C. lacertoides. Nevertheless, we found that both species have indistinguishable hyoid morphology, bearing C. lacertoides a noticeable second pair of ceratobranchials. Besides, we realized that the pattern of coloration in this species is more variable than previously considered. As a result of the present work, C. charrua is included in the synonymy of C. lacertoides. In addition, we provide some observations on the holotype of Cnemidophorus grandensis, a junior synonym of C. lacertoides.

Amphibian chytridiomycosis caused by Batrachochytrium dendrobatidis is reported in Uruguayan native amphibians for the first time. Histological evidence of infection was observed in tadpoles of Hypsiboas pulchellus, Odontophrynus maisuma, Physalaemus henselii, and Scinax squalirostris. The effects of chytridiomycosis on these species are still unknown. However, the disease is of potential concern for the conservation of the apparently declining species P. henselii and also for O. maisuma, given its restricted distribution in habitats which are being increasingly disturbed.