Abstract Sampling gaps across the logistically challenging and extremely biodiverse Amazonia largely hamper our understanding of broad-scale amphibian and reptile diversity patterns in this ecosystem. The Juruá River basin, a southwestern tributary of the Amazon River, is one of these undersampled areas, with only punctual information documented for these vertebrates that are spatially or temporally biased. This is especially the case for the lower-middle courses of the Juruá River, which also has comparatively less protected areas than its upper course. In order to fill some biodiversity knowledge gaps associated with amphibians and reptiles in this river basin, we combined results of our field expeditions carried out in 1992, 2005-2007, and 2018 to the Reserva Extrativista (Extractive Reserve) do Baixo Juruá, a Brazilian protected area in the right bank of the lower Juruá River. Amphibians and reptiles were sampled using four complementary methods: active surveys, pitfall traps, funnel traps, and trammel nets. We identified species or updated their taxonomic status with a reanalysis of the external morphology of the preserved material in the light of novel taxonomic literature (more than 1,500 specimens) and employment of DNA barcoding analyses for some newly collected specimens with contentious taxonomic status. Our combined sampling evidenced 149 species of amphibians and reptiles occurring in this protected area (72 amphibians, 68 squamates, six chelonians, and three crocodilians). Recorded species highlight the value of the lower Juruá River region as harboring quite diverse assemblages for these vertebrates, with species typical of the western and southwestern Amazonia sub-regions. Remarkable species records are presented, as well as accounts on species with lower taxonomic resolution. Furthermore, we discuss the biogeographic affinities of recorded assemblages based on the species geographic range and preferred habitats, and the value of this protected area to preserve the regional biological diversity.

Natural history accounts are presented for six species of anuran amphibians from the Manaus region, Amazonas. Varied information concerning advertisement call, clutch size, hatching success, and reproductive behavior for two species of dendrobatids and four species of hylids. The information was gathered over several years of field work and hopefully will serve to better understand the ecology of these species.

Thirty-three species of anuran amphibians and 22 species of reptiles were found in 9 days and nights of sampling in an unexplored region of Central Amazon. The community is characterized by typical lowland Amazonian species. The relatively short sampling time and high number of species caught indicates that this region probably has very high species richness.

An experiment was set-up to see in mortality inflicted by tadpole predators depends on prey and predator sizes. Fish and dragonfly larvae were used as predators and two size classes of Osteocephalus taurinus tadpoles as prey. Results show that the effect of predators is dependent on the size structure of the prey population. Furthermore, dragonfly larvae are more voracious predators than the fish used in the experiment. Both predators occur in natural ponds where Osteocephalus taurinus lays its eggs. The timing of arrival of predators and prey, which determines the relative sizes of predators and prey, is an important factor determining the outcome of an episode of community interaction in tropical ponds, as in similar temperate systems.

The tadpole of Atelopus pulcher is described for the first time. Tadpoles of this species were encountered in large streams where reproduction occurs. Tadpoles of this species conform to the genus characteristics in exhibiting an enlarged ventral disc and a 2/3 tooth row formula. One characteristic, however, distinguishes this species from other Atelopodids in that the upper beak is shorter than the lower beak.