To test the hypothesis that subtle differences in abiotic requirements can result in almost total spatial segregation, we sampled two species of diurnal frogs, Atelopus spumarius and Allobates sumtuosus, in a primary forest reserve in central Brazilian Amazonia. We conducted visual and acoustic surveys on three occasions over 2 months, in 40 streamside (riparian) plots distributed throughout the reserve's two major drainage basins, using a grid system that covers 64 km 2 . On average, drainages differed in the pH of stream water and the number of connected and isolated streamside pools. Differences in abiotic characteristics of drainages were associated with the spatial distribution of frog species. The occurrence and density of Allobates sumtuosus was negatively related to stream pH and discharge and positively related to the number of isolated pools in plots. The occurrence and density of Atelopus spumarius was associated with streams with high discharge and pH near neutral. These results indicate that although very large reserves will probably contain sufficient landscape heterogeneity to accommodate different species of diurnal frogs, due to strongly patchy distributions, in situ studies using fine-scale species-distribution models will be necessary to assess the adequacy of small reserves in Amazonia that cover hundreds of square kilometers or less for the conservation of some anuran species.Abstract in Portuguese is available with online material.

The Manaus harlequin frog is an evolutionarily significant clade within the Atelopus hoogmoedi species complex. Analyses of 16S and COI concatenated sequences support Atelopus from the Manaus region as an evolutionary significant unit, sister of all species of a Guiana Shield clade. A previous study showed that subtle changes in stream characteristics influence the Manaus harlequin frog occurrence and density variation at local‐scale in a reserve on the outskirts of Manaus. As deforestation is approaching areas where the Manaus harlequin frog occurs, we asked how site and landscape heterogeneity influence the geographic boundaries, occurrence patterns, and density variation of the Manaus harlequin frog. We searched for the frog in 80 plots that measured 250 m by 4 m on banks of first‐ to third‐order streams during the rainy seasons in 2012–2013 and 2016–2019. The plot distribution covered all likely areas of occurrence of the Manaus harlequin frog and extended to the areas where it is substituted by its geographically closest relative on the Guiana Shield. Ecological drivers related to climate, flooding events, and forest structure apparently restrict the Manaus harlequin frog to a patchy distribution in a narrow portion of the interfluve between the Negro and Uatuma Rivers. Densities of individuals varied in response to subtle changes in floodplain and stream characteristics. The Manaus harlequin frog is associated with a very specific habitat that is directly affected by the growth of Manaus, the largest city in Amazonia. We conclude that it is endangered and urgent actions are required for its conservation.

We used integrative taxonomy to describe a new species of Atelopus from the lowlands of Central Amazonia in the region of Manaus, Amazonas, Brazil. The new species is geographically isolated from the southernmost species of Atelopus of the Guiana Shield. Atelopus manauensis species nova (sp. nov.) is characterized by the combination of the following characteristics: male snout-vent length range (SVL = 19.1–26.4 mm; n = 11); dorsal and lateral skin smooth; ventral surface entirely white or white with cream-colored gular region; fingers and toes lacking subarticular tubercles and fringes. The advertisement call of the new species has a call duration of 689–840 ms, contains 15–26 pulses, is emitted at an average pulse rate of 25.5 pulses per second, and has a dominant frequency ranging 3088–3610 Hz. The genetic divergence between the new species and its morphologically most similar congeners (A. spumarius and A. pulcher) is greater than 4%. Atelopus manauensis sp. nov. is closely related to species of the A. hoogmoedi complex inhabiting the Guiana Shield. The new species has a small geographic distribution (approximately 4500 km2) in a landscape that is strongly threatened by the growth of Manaus, the largest city in Brazilian Amazonia. The new species is considered critically endangered and in need of urgent conservation measures.

This work presents the first data on incubation temperature of Phrynops geoffroanus (Schweigger, 1812) in a natural environment, and provides information on nest predation, hatching success and size of offspring born in the nests on sandy beaches along the Upper Xingu River. Thirty-one P. geoffroanus nests were found, of which eleven were completely predated, mainly by Cerdocyon thous (Linnaeus, 1766). Incubation was completed in nine out of the 17 nests protected by netting. The nests presented an average of 13.1 eggs and were distributed over the various geomorphological sectors of the nine sampled beaches. The size and weight of the hatchlings varied significantly between nests, and the incubation period in protected nests lasted for 76.5 days, less than reported for controlled incubation in the laboratory. Daily variation in incubation temperature in the three nests monitored for temperature was lower in those situated in fine sand sediments. Incubation temperature varied from 22 to 39 C and may have affected hatching success, which reached 60.8% in protected nests. Nest distribution in different geomorphological sectors indicated the plasticity of P. geoffroanus in terms of variation in nesting environment, which partly explains the species' broad geographical distribution

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Amphibians and reptiles are diversified in the Cerrado biome but have been threatened by habitat loss and fragmentation, as well as lack of understanding of their distribution. Therefore, collection and organization of information about species in natural environments are essential for conservation, especially in Protected areas (PAs) and their adjacent zones. We present information about the composition and structure of the herpetofauna from Parque Estadual da Serra de Caldas Novas (PESCAN) and its representativeness in comparison to other PAs in the Cerrado. Fieldwork was conducted in 12 sampling sites from February 2009 to February 2010, using active search and pitfall traps. We recorded 41 species of amphibians, with greatest richness in sites with open vegetation and water bodies. Reptiles were represented by 32 species, with the greatest species richness in cerrado open environments. Both amphibian and reptile communities were more similar to those from geographically closer PAs and located in the central region of the Cerrado (State of Goiás and Distrito Federal). The PESCAN holds 24.85% and 17.98% of amphibians and reptiles species occurring in Cerrado PAs, respectivelly. This large representativeness and the high number of endemisms (18 amphibians and 7 reptiles) emphasize the importance of the PESCAN, together with other PAs, for the maintenance of regional biodiversity. In addition, we also encourage researches evaluating amphibian and reptile communities outside PAs, such as legal reserves, and we suggest new approaches to study the biodiversity of protected areas.

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Infectious diseases are one of the main threats to biodiversity. The fungus Batrachochytrium dendrobatidis (Bd) is associated with several amphibian losses around the globe, and environmental conditions may dictate the success of pathogen spread. The Brazilian Amazon has been considered climatically unsuitable for chytrid fungus, but additional information on Bd dynamics in this ecoregion is still lacking. We sampled 462 amphibians (449 anurans, 4 caudatans and 9 caecilians), representing 57 species from the Brazilian Amazon, and quantified Bd infections using qPCR. We tested whether abiotic variables predicted the risk of Bd infections, and tested for relationships between biotic variables and Bd. Finally, we experimentally tested the effects of Bd strains CLFT 156 and CLFT 102 (from the southern and northern Atlantic Forest, respectively) on Atelopus manauensis. We detected higher Bd prevalence than those previously reported for the Brazilian Amazon, and positive individuals in all 3 orders of amphibians sampled. Both biotic and abiotic predictors were related to prevalence, and no variable explained infection load. Moreover, we detected higher Bd prevalence in forested than open areas, while the host’s reproductive biology was not a factor. We detected higher mortality in the experimental group infected with CLFT 156, probably because this strain was isolated from a region characterized by discrepant climatic conditions (latitudinally more distant) when compared with the host’s sampling site in Amazon. The lowland Brazilian Amazon is still underexplored and future studies targeting all amphibian orders are essential to better understand Bd infection dynamics in this region.