Determinants of anuran assemblages in Amazonian White-sand Ecosystems.

Amazonian white-sand ecosystems have predominantly sandy soils and a high amount of endemism, and several species found within them are adapted to long periods of drought. However, little is known about the variation in the structure of anuran assemblages in these ecosystems. Considering that most species are not uniformly distributed in heterogeneous landscapes, we tested the hypothesis that anuran assemblage variation in white-sand ecosystems is related to changes in vegetation structure. Specifically, we focused on a heterogeneous patch of white-sand ecosystems of the central Amazon and evaluated whether vegetation structure and soil characteristics, including root depth, influence the richness, abundance, and composition of anuran assemblages. Our results showed that low amounts of clay in the soil play an important role in structuring vegetation in these ecosystems, and these are the main factors that organize anuran assemblages. The Campinaranas close to the water bodies have a high species richness, while Campina landscapes limit the occupation of most of species. Our findings indicate that anurans undergo environmental filtering in white-sand ecosystems and are organized into hierarchical subgroups, in which only species with specialized reproduction can successfully occupy the most water-restricted environments.

Disentangling the veil line for Brazilian biodiversity: An overview from two long-term research programs reveals huge gaps in ecological data reporting.

The lack of synthesized information regarding biodiversity is a major problem among researchers, leading to a pervasive cycle where ecologists make field campaigns to collect information that already exists and yet has not been made available for a broader audience. This problem leads to long-lasting effects in public policies such as spending money multiple times to conduct similar studies in the same area. We aim to identify this knowledge gap by synthesizing information available regarding two Brazilian long-term biodiversity programs and the metadata generated by them. Using a unique dataset containing 1904 metadata, we identified patterns of metadata distribution and intensity of research conducted in Brazil, as well as where we should concentrate research efforts in the next decades. We found that the majority of metadata were about vertebrates, followed by plants, invertebrates, and fungi. Caatinga was the biome with least metadata, and that there's still a lack of information regarding all biomes in Brazil, with none of them being sufficiently sampled. We hope that these results will have implications for broader conservation and management guiding, as well as to funding allocation programs.

Diversification of the terrestrial frog genus Anomaloglossus (Anura, Aromobatidae) in the Guiana Shield proceeded from highlands to lowlands, with successive loss and reacquisition of endotrophy.

Two main landscapes emerge from the Guiana Shield: the highlands to the west called the Pantepui region and the Amazonian lowlands to the east, both harbouring numerous endemic species. With 32 currently recognized species, the genus Anomaloglossus stands out among Neotropical frogs as one that diversified only within the Guiana Shield both in the highlands and the lowlands. We present a time-calibrated phylogeny obtained by using combined mitogenomic and nuclear DNA, which suggests that the genus originates from Pantepui where extant lineages started diversifying around 21 Ma, and subsequently (ca. 17 Ma) dispersed during the Miocene Climatic Optimum to the lowlands of the eastern Guiana Shield where the ability to produce endotrophic tadpoles evolved. Further diversification within the lowlands in the A. stepheni group notably led to an evolutionary reversal toward exotrophy in one species group during the late Miocene, followed by reacquisition of endotrophy during the Pleistocene. These successive shifts of reproductive mode seem to have accompanied climatic oscillations. Long dry periods might have triggered evolution of exotrophy, whereas wetter climates favoured endotrophic forms, enabling colonization of terrestrial habitats distant from water. Acquisition, loss, and reacquisition of endotrophy makes Anomaloglossus unique among frogs and may largely explain the current species diversity. The micro evolutionary processes involved in these rapid shifts of reproductive mode remain to be revealed.

A new species of Pristimantis (Anura: Strabomantidae) from white-sand forests of central Amazonia, Brazil.

The white-sand ecosystems in the Solimões-Negro Interfluve are among the less studied in Amazonia. Recent herpetological surveys conducted west of Manaus, Brazil (central Amazonia) indicate that white-sand forests host a unique anuran fauna comprising habitat specialized and endemic species. In the present study we describe a new species of rain frog belonging to the Pristimantis unistrigatus species group from the white-sand forest locally called "campinarana" (thin-trunked forests with canopy height below 20 m). The new species is phylogenetically close to rain frogs from western Amazonian lowlands (P. delius, P. librarius, P. matidiktyo and P. ockendeni). It differs from its closest relatives mainly by its size (male SVL of 17.3-20.1 mm, n = 16; female SVL of 23.2-26.5 mm, n = 6), presence of tympanum, tarsal tubercles and dentigerous processes of vomers, its translucent groin without bright colored blotches or marks, and by its advertisement call (composed of 5-10 notes, call duration of 550-1,061 ms, dominant frequency of 3,295-3,919 Hz). Like other anuran species recently discovered in the white-sand forests west of Manaus, the new species seems to be restricted to this peculiar ecosystem.

Chytrid fungus in amphibians from the lowland Brazilian Amazon.

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.

A new nurse frog of the Allobates tapajos species complex (Anura: Aromobatidae) from the upper Madeira River, Brazilian Amazonia.

Cryptic diversity is extremely common in widespread Amazonian anurans, but especially in nurse frogs of the genus Allobates. There is an urgent need to formally describe the many distinct but unnamed species, both to enable studies of their basic biology but especially to facilitate conservation of threatened environments in which many are found. Here, we describe through integrative taxonomy a new species of the Allobates tapajos species complex from the upper Madeira River, southwestern Amazonia. Species delimitation analyses based on molecular data are congruent and delimit five candidate species in addition to A. tapajos sensu stricto. The new species is recovered as sister to A. tapajos clade F, a candidate species from Teles-Pires River, southeastern Amazonia. The new species differs from nominal congeners in adult and larval morphology and in male advertisement call. Egg deposition sites differ between east and west banks of the upper Madeira River, but there is no evidence of corresponding morphologic or bioacoustic differentiation. The new species appears to be restricted to riparian forests; its known geographic range falls entirely within the influence zone of reservoirs of two large dams, which underscores the urgent need of a conservation assessment through long-term monitoring. This region harbors the richest assemblage of Allobates reported for Brazilian Amazonia, with six nominal species and four additional candidate species awaiting formal description.

Long-term standardized ecological research in an Amazonian savanna: a laboratory under threat.

A few decades ago, researchers from the National Institute for Amazonian Research (INPA) started a pilot study to integrate the ecological studies of several organisms using monitoring plots, which then became the embryo for the creation of the RAPELD (Rapid Assessments and Long-term Ecological Research) system used by the Program for Biodiversity Research (PPBio) and the Long-term ecological research site POPA (PELD Western Pará). They installed and maintained permanent plots in an Amazonian-savanna patch near to the village of Alter do Chão. Amazonian savannas constitute a threatened ecosystem comprising only 6% of the Amazon biome. Most of the studies focused on three main long-term ecological research questions, but the site was also of importance for other inquiries and for the training of young researchers, contributing 71 articles so far and 32 masters and doctorate theses. Here, we present the experimental design and results of standardized studies in the savannas and forest fragments near Alter do Chão that have been carried out over the years. We discuss the future prospects and local threats to the area (e.g. soy crops and land speculation), and highlight the need to incorporate Alter do Chão villagers in land-use planning in the region.

Impacts of an Amazonian hydroelectric dam on frog assemblages.

About 90% of the Amazon's energy potential remains unexploited, with many large hydroelectric dams yet to be built, so it is important to understand how terrestrial vertebrates are affected by reservoir formation and habitat loss. We investigated the influence of the construction of the Santo Antônio Hydroelectric dam on the Madeira River in southwestern Amazonia on the structure of frog assemblages based on samples collected in two years before the dam flooded (pre-stage) and one (post1-stage) and four years (post2-stage) after its construction. We surveyed five 500-ha plot systems three times during each stage; in the pre-stage we sampled 19 plots in low-lying areas that would be flooded by the dam, (from now called flooded pre-stage plots) and 45 plots in terra-firme forest (from now called unflooded pre-stage plots). At the post1-stage we sampled the 45 unflooded plots and in the post2-stage we sampled the remaining 39 unflooded plots. We detected frogs by active visual and acoustic searches standardized by both time and sampling area. Few species recorded in the pre-stage flooded plots were not found in the pre-stage unflooded plots or in stages after flooding. However, the composition of frog assemblages based on relative densities in flooded pre-stage plots did not re-establish in plots on the new river margins. In unflooded areas, frog assemblages were distinct among the flooding stages with no tendency to return to the original assemblage compositions even four years after the dam was filled. For the areas that were not flooded, there was an increase in species richness in 82% of the plots between the surveys before dam construction and the first surveys after dam completion, and 65% between the pre-stage and surveys four years after dam completion. Lack of understanding by the controlling authorities of the long-term effects of landscape changes, such as water-table rises, means that studies covering appropriate periods post construction are not required in legislation, but the data from Santo Antônio indicate that changes due to dam construction are either long-term or difficult to distinguish from natural fluctuations. Future environmental-impact studies should follow strict BACI designs.

Key roles of paternal care and climate on offspring survival of an Amazonian poison frog.

In poison frogs (Dendrobatoidea), usually the males are territorial, care for terrestrial nests and later transport their offspring to waterbodies where they complete larval development. In some species, mothers care for their offspring or may exhibit flexible care to compensate for father absence. We conducted a multi-season field experiment with the Amazonian species Allobates paleovarzensis, in which it was possible to study the joint impact of paternal care and the El Niño climatic anomaly on offspring survival. The experiment consisted of two treatments: non-removal, and removal of the father from their territories. We observed that parental care was performed exclusively by the father, and none of the mothers of the 21 monitored nests transported the tadpoles. We also observed that the severe drought in a year under the influence of the El Niño event caused such a high mortality in all pre-metamorphic stages, that the role of parental care became irrelevant for offspring survival during that season. We found that pre-metamorphic Allobates paleovarzensis are highly vulnerable to the loss of paternal care. In addition, we showed that paternal care, when present, does not prevent offspring death under these increasingly frequent climatic anomalies.

Evaluation of benzocaine-based anesthetic gel in anuran skins extracts: A case study using the frog Lithodytes lineatus (Anura: Leptodactylidae).

Extracts made from the skin of dead Lithodytes lineatus frog individuals with the application of the benzocaine-based anesthetic gel, introduced into the oral cavity, were analyzed by 1H Nuclear Magnetic Resonance to investigate whether the application of this product (oral) can make studies that use extracts from the skins of these animals unfeasible. For comparison, we used skins of another species of anuran following the same death protocol. No trace of the benzocaine substance was found in the 1H-NMR spectra of the skin extracts from any of the tested anuran species. Still, using the hierarchical clustering model, it was possible to observe the formation of well-defined groups between the skin extracts of anurans and the anesthetic used to kill these animals. Our results suggest that the lethal dose of benzocaine in gel used inside the mouth of frogs may have no influence on potential results regarding the chemical composition or even bioassays using extracts made from the skin of these animals killed under this protocol since there was no detection of this substance for the analyzed samples.

A new nurse frog (Anura: Allobates) from Brazilian Amazonia with a remarkably fast multi-noted advertisement call.

Nurse frogs (Aromobatidae: Allobates) are probably the most extensively studied genus by taxonomists in Brazilian Amazonia. The southwestern portion of Amazonia is the most species-rich: as many as seven species may occur in sympatry at a single locality. In this study, we describe a new species of nurse frog from this region. The description integrates data from larval and adult morphology, advertisement calls and DNA sequences. Allobates velocicantus sp. nov. is distinguished from other Allobates mainly by the absence of hourglass-shaped dark marks on the dorsum and dark transverse bars on the thigh; a throat that is white centrally and yellow marginally; basal webbing on toes II and III; finger I longer than finger II; and an advertisement call composed of 66-138 pulsed notes with a note duration of 5-13 ms, inter-note intervals of 10-18 ms and a dominant frequency of 5,512-6,158 Hz. Tadpoles of the new species have 3-4 short, rounded papillae on the anterior labium, 16-23 papillae on the posterior labium, and a labial keratodont row formula 2(2)/3(1). This is the fifth species of Allobates described from the state of Acre, southwestern Brazilian Amazonia.

The Influence of Environmental Variation on the Genetic Structure of a Poison Frog Distributed Across Continuous Amazonian Rainforest.

Biogeographic barriers such as rivers have been shown to shape spatial patterns of biodiversity in the Amazon basin, yet relatively little is known about the distribution of genetic variation across continuous rainforest. Here, we characterize the genetic structure of the brilliant-thighed poison frog (Allobates femoralis) across an 880-km-long transect along the Purus-Madeira interfluve south of the Amazon river, based on 64 individuals genotyped at 7609 single-nucleotide polymorphism (SNP) loci. A population tree and clustering analyses revealed 4 distinct genetic groups, one of which was strongly divergent. These genetic groups were concomitant with femoral spot coloration differences, which was intermediate within a zone of admixture between two of the groups. The location of these genetic groups did not consistently correspond to current ecological transitions between major forest types. A multimodel approach to quantify the relative influence of isolation-by-geographic distance (IBD) and isolation-by-environmental resistance (IBR) nevertheless revealed that, in addition to a strong signal of IBD, spatial genetic differentiation was explained by IBR primarily linked to dry season intensity (r2 = 8.4%) and canopy cover (r2 = 6.4%). We show significant phylogenetic divergence in the absence of obvious biogeographical barriers and that finer-scaled measures of genetic structure are associated with environmental variables also known to predict the density of A. femoralis.

A new species of Dendropsophus (Anura, Hylidae) from southwestern Amazonia with a green bilobate vocal sac.

Recent studies have shown that species diversity of the South American frog genus Dendropsophus is significantly underestimated, especially in Amazonia. Herein, through integrative taxonomy a new species of Dendropsophus from the east bank of the upper Madeira River, Brazil is described. Based on molecular phylogenetic and morphological analyses, the new species is referred to the D. microcephalus species group, where it is differentiated from its congeners mainly by having a green bilobate vocal sac and an advertisement call comprising 1-4 monophasic notes emitted with a dominant frequency of 8,979-9,606 Hz. Based on intensive sampling conducted in the study area over the last ten years, the new species is restricted to the east bank of the upper Madeira River, although its geographic range is expected to include Bolivian forests close to the type locality.

Hierarchical effects of historical and environmental factors on lizard assemblages in the upper Madeira River, Brazilian Amazonia.

Investigating the role of historical and ecological factors structuring assemblages is relevant to understand mechanisms and processes affecting biodiversity across heterogeneous habitats. Considering that community assembly often involves scale-dependent processes, different spatial scales may reveal distinct factors structuring assemblages. In this study we use arboreal and leaf-litter lizard abundance data from 83 plots to investigate assemblage spatial structure at two distinct scales in southwestern Brazilian Amazonia. At a regional scale, we test the general hypothesis that the Madeira River acts as a barrier to dispersal of some lizard species, which results in distinct assemblages between river banks. At a local scale, we test the hypothesis that assemblages are not evenly distributed across heterogeneous habitats but respond to a continuum of inadequate-to-optimal portions of environmental predictors. Our results show that regional lizard assemblages are structured by the upper Madeira River acting as a regional barrier to 29.62% of the species sampled. This finding suggests species have been historically isolated at one of the river banks, or that distinct geomorphological features influence species occurrence at each river bank. At a local scale, different sets of environmental predictors affected assemblage composition between river banks or even along a river bank. These findings indicate that environmental filtering is a major cause of lizard assemblage spatial structure in the upper Madeira River, but predictor variables cannot be generalized over the extensive (nearly 500 km) study area. Based on a single study system we demonstrate that lizard assemblages along the forests near the banks of the upper Madeira River are not randomly structured but respond to multiple factors acting at different and hierarchical spatial scales.

The evolution of polymorphism in the warning coloration of the Amazonian poison frog Adelphobates galactonotus.

While intraspecific variation in aposematic signals can be selected for by different predatory responses, their evolution is also contingent on other processes shaping genetic variation. We evaluate the relative contributions of selection, geographic isolation, and random genetic drift to the evolution of aposematic color polymorphism in the poison frog Adelphobates galactonotus, distributed throughout eastern Brazilian Amazonia. Dorsal coloration was measured for 111 individuals and genetic data were obtained from 220 individuals at two mitochondrial genes (mtDNA) and 7963 Single Nucleotide Polymorphisms (SNPs). Four color categories were described (brown, blue, yellow, orange) and our models of frog and bird visual systems indicated that each color was distinguishable for these taxa. Using outlier and correlative analyses we found no compelling genetic evidence for color being under divergent selection. A time-calibrated mtDNA tree suggests that the present distribution of dorsal coloration resulted from processes occurring during the Pleistocene. Separate phylogenies based on SNPs and mtDNA resolved the same well supported clades, each containing different colored populations. Ancestral character state analysis provided some evidence for evolutionary transitions in color type. Genetic structure was more strongly associated with geographic features, than color category, suggesting that the distribution of color is explained by localized processes. Evidence for geographic isolation together with estimates of low effective population size implicates drift as playing a key role in color diversification. Our results highlight the relevance of considering the neutral processes involved with the evolution of traits with important fitness consequences.

Rediscovery of Osteocephalus vilarsi (Anura: Hylidae): an overlooked but widespread Amazonian spiny-backed treefrog.

Osteocephalus vilarsi (Melin, 1941) is an Amazonian treefrog species known for over 75 years from its holotype only. Due to a lack of published data on its morphological diagnostic characters and their variations, as well as the absence of molecular, acoustic and ecological data supporting its identity, a highly dynamic taxonomic history has led this species to be confused and even synonymised with other Osteocephalus species from distinct species groups. The molecular phylogenetic relationships of O. vilarsi were investigated based on recently collected specimens from eight Northwestern Brazilian localities in the state of Amazonas, leading to its removal from the Osteocephalus taurinus species group and placement in the Osteocephalus planiceps species group. Furthermore, detailed data on morphology and colour variation are provided, as well as advertisement call and tadpole descriptions. Finally, the currently known geographic range of O. vilarsi is considerably extended, first data on the natural history of the species are provided, and the possible ecological preference of O. vilarsi for Amazonian white-sand forests is discussed.

Author Correction: Sole coloration as an unusual aposematic signal in a Neotropical toad.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A new nurse frog of Allobates masniger-nidicola complex (Anura, Aromobatidae) from the east bank of Tapajós River, eastern Amazonia.

The small nurse frogs of the genus Allobates (Anura, Aromobatidae) represent one of the most challenging taxonomic issues of the Neotropics. During several amphibian surveys in the Middle Tapajós River region, state of Pará, Brazil, we collected phenotypic, ecological, and molecular data on species of this genus, leading to the identification of a new species included in the Allobates masniger-nidicola complex. The new species is characterized by a large body size (snout-vent length 19.2-21.7 mm in males and 19.3-22.0 mm in females), finger III not swollen in adult males; cryptic external coloration, with dorsum uniformly ochre; a dark brown lateral stripe and a pale cream ventrolateral stripe; limbs ranging from ochre to orange; throat and chest violaceous in males and yellowish in females. The advertisement call is usually arranged in bouts of four closely spaced notes, which we term 4-pulsed units of repetition (UR), 0.317 s long on average, followed by silent intervals, and an average dominant frequency of 4.163 kHz. The new species also has exotrophic tadpoles with a unique fin morphology, which begins after the body-tail insertion and is deeper posteriorly to half of the caudal length. Sequencing of the 16S and COI regions of the mitochondrial DNA show a genetic p-distance of approximately 6-10% compared to closely related congeners. We discuss the biogeography of the new species based on phylogenetic relationships of the species within the Allobates masniger-nidicola complex and the allopatric geographic distribution in relation to sister taxa. Functional characteristics and geographic restrictions make this species particularly sensitive to the increasing human impact in eastern Amazonia.

A new species of Amazophrynella (Anura: Bufonidae) with two distinct advertisement calls.

Here we describe a new species of the toad genus Amazophrynella (Bufonidae) from the south margin of the Amazon River in Santarém, state of Pará, Brazilian Amazonia. The new species can be diagnosed by (1) medium body size for the genus: adult females 19.5-20.4 mm SVL, adult males 13.0-14.5 mm SVL; (2) snout acuminate in lateral view; (3) Finger I larger and robust; (4) Finger I nearly equal in size than Finger II; (5) palmar tubercle rounded, covering » of hand; (6) pigmented callus in Finger I in males; in life: (7) brown stain on throat and chest; (8) black dots on venter. Males emit two distinct advertisement calls: the call type 1 consists of a relatively long note (mean 0.248 s) with a mean dominant frequency of 3526 Hz. The call type 2 is arranged in bouts of 6 to 22 notes with mean dominant frequency of 3450 Hz and much shorter note durations (mean 0.034 s). In this study we also redescribe the advertisement call of A. minuta, which also emits a second call type.

Comparative cytogenetics of nine populations of the Rhinella genus (Anura, Bufonidae) with a highlight on their conservative karyotype.

The genus Rhinella is one of the most diverse groups of bufonid toads, currently composed by 93 valid species and naturally distributed throughout different Neotropical ecoregions. Here, we analyze nine Brazilian populations of toads representing species of the Rhinella margaritifera and Rhinella marina groups. These new data include the first description of the R. hoogmoedi and R. proboscidae karyotypes, as well as other taxonomically unresolved forms. Chromosomal analysis of the populations revealed pronounced chromosomal uniformity (2n=22), including the diploid number and chromosomal morphology. Three different NOR-bearing chromosomes were identified: in the subterminal region of pair 10q in R. hoogmoedi, Rhinella sp. 1 and Rhinella sp. 2, in subterminal region of 7p in R. proboscidae and Rhinella cf. margaritifera while in R. henseli and R. icterica was detected in interstitial region of 7p. Karyotypic uniformity of the genus permits the inference of interspecific chromosome homologies and evolutionary changes in the NOR-bearing chromosome may represent an informative character in species group level. The review of the cytogenetic data of the Rhinella species together with the new karyotypes reported here contributes to the understanding of the chromosomal evolution of these toads, which karyotypes are highly conserved despite the ample distribution of many forms.