The challenge in detecting risk areas of snakebite when case rates are low: the case of Amazonian coral snakes

Identifying risk areas for envenomation by animals is relevant for public health, such as strategic distribution of antivenoms. Coral snakes are highly diverse in the Amazon, inhabit natural and human-modified environments, and the outcome of the cases tends to be serious and potentially lethal due to their neurotoxic venom. By integrating species' geographical records and environmental variables, we used species distribution modeling to predict the distribution of coral snake species in the Brazilian Amazonia. We analyzed the relationship between the predicted distribution of coral snake species, along with envenomation data in the region, to propose actions to reduce the number of cases and to provide tools for a better policy of public health. We conclude that the entire Amazon shows high environmental suitability for coral snakes, and such suitability explains little about the incidence of cases. This is probably due to the low human density in the Amazon and to coral snake traits such as secretive habits and non-agressive behavior. Differently from other venomous snakes, the scenario regarding coral snakebites precludes the detection of prominent geographical areas of concern and demands a broad and equitable availability of health centers throughout Amazonia and along other areas of occurrence of the genus Micrurus.

Envenomation by Micrurus hemprichii in Brazilian Amazonia: A report of three cases

Herein, we report three new separate cases of human envenomations by Micrurus hemprichii for the Amazon, which is a biome where envenomations by Micrurus are seldom reported. Two women were bitten after stepping on the snakes and one man was bitten while handling the animal. All cases occurred in the peridomicile, in rural areas. The first case evolved mainly to local symptoms, but the patient was discharged before the identification of the snake and had to be called back for observation before being eventually discharged. In the second case, the patient presented transitory dyspnea and she was discharged after four days in hospital. In the third case, the patient showed only local symptoms, but he was about to receive unnecessary antivenom against coral snakes. Cases like these show the importance of educational problems regarding local venomous snakes in order to avoid bites and to provide the correct hospital treatment. For this, trained professionals in cases involving venomous animals are needed.

The Amazonian kambô frog Phyllomedusa bicolor (Amphibia: Phyllomedusidae): Current knowledge on biology, phylogeography, toxinology, ethnopharmacology and medical aspects

Phyllomedusa bicolor (Phyllomedusidae), popularly known as the kambô in Brazil, is a tree frog that is widely distributed in South American countries and is known for producing a skin secretion that is rich in bioactive peptides, which are often used in indigenous rituals. The biological effects of the skin secretion were observed in the first studies with indigenous communities. Over the last six decades, researchers have been studying the chemical composition in detail, as well as the potential pharmacological applications of its constituents. For this reason, indigenous communities and health agents fear the misuse of the kambô, or the inappropriate use of the species, which can result in health complications or even death of users. This article seeks to provide a transdisciplinary review that integrates knowledge regarding the biology of P. bicolor, ethnoknowledge about the ritual of the kambô, and the chemistry and pharmacology of the skin secretion of this species, in addition to medical aspects of the indiscriminate use of the kambô. Furthermore, this review seeks to shed light on perspectives on the future of research related to the kambô.

Ticks on reptiles and amphibians in Central Amazonia, with notes on rickettsial infections

Reptiles and amphibians are exceptional hosts for different ectoparasites, including mites and ticks. In this study, we investigated tick infestations on reptiles and amphibians trapped in Central Amazonia, and also assessed the presence of rickettsial infections in the collected ticks. From September 2016 to September 2019, 385 reptiles (350 lizards, 20 snakes, 12 tortoises, and three caimans) and 120 amphibians (119 anurans and one caecilian) were captured and examined for ectoparasites. Overall, 35 (10%) lizards, three (25%) tortoises and one (0.8%) toad were parasitized by ticks (124 larvae, 32 nymphs, and 22 adults). In lizards, tick infestation varied significantly according to landscape category and age group. Based on combined morphological and molecular analyses, these ticks were identified as Amblyomma humerale (14 larvae, 12 nymphs, 19 males, and one female), Amblyomma nodosum (three larvae, one nymph, and one female), and Amblyomma rotundatum (four larvae, three nymphs, and one female), and Amblyomma spp. (103 larvae and 16 nymphs). Our study presents the first records of A. nodosum in the Amazonas state and suggests that teiid lizards are important hosts for larvae and nymphs of A. humerale in Central Amazonia. Moreover, a nymph of A. humerale collected from a common tegu (Tupinambis teguixin) was found positive for Rickettsia amblyommatis, which agrees with previous reports, suggesting that the A. humerale-R. amblyommatis relationship may be more common than currently recognized.

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.

Envenomations by coral snakes in an Amazonian metropolis: Ecological, epidemiological and clinical aspects

Envenomation by coral snakes represents a little known burden in Brazilian Amazonia. So far, details on clinical and epidemiological aspects remain obscure in the region. We gathered data from medical charts and from the scientific collection of snakes from Fundação de Medicina Tropical Doutor Heitor Vieira Dourado, finding 26 cases of envenomation by five species of Micrurus in Manaus region, between 1987 and 2018. They represent 0.7% of the snakebites treated in the hospital since the records began, in 1979. Micrurus lemniscatus was responsible for most of the bites (10), followed by M. hemprichii (five), M. spixii (three), M. surinamensis (three) and M. averyi (one). There was no difference between the sexes of the snakes that caused bites. Patients were mostly males, and most of the cases were reported in urban areas. Bites predominated in dry season, and there was a clear geographical segregation among species. We describe seven cases of envenomation, three mild and four severe, all of which evolved to cure. Paresthesia (six), pain (five) and edema (four) were the most common local symptoms. Systemic features such as dyspnea/shallow breath (four), palpebral ptosis (four), blurred vision (three), dysarthria (three) and difficulty to walk (three) were also detected. Two patients bitten by Micrurus sp. and M. hemprichii, showed slight increased serum levels of creatine kinase (reference level <190 U/L), 1184 U/L and 1229 U/L, respectively, indicative of mild systemic myotoxicity. This is the first report of myotoxic manifestation in the envenomation by M. hemprichii. No patient developed respiratory failure, though one bitten by an adult M. spixii required intubation and mechanical ventilation due to decreased level of consciousness during evolution, probably related to induced sedation caused by concurrent alcohol intoxication. All patients were treated with Brazilian Micrurus antivenom (soro antielapídico, median = 10 vials). Six patients were pretreated intravenously with H1 and H2 antagonists and steroids, with two patients developing early adverse reactions. The median length of hospital stay was four days. Envenomations by coral snakes in Manaus region are clinically severe, but rare and sparsely distributed over time, making the detection of epidemiological and clinical patterns a challenge for public health.

Hidden diversity within the broadly distributed Amazonian giant monkey frog (Phyllomedusa bicolor: Phyllomedusidae)

Phyllomedusa bicolor is a large-sized nocturnal tree frog found in tropical rainforests throughout much of the Amazonian region of Brazil, Colombia, Bolivia, Peru, Venezuela, and the Guianas. Very little is known about P. bicolor genetic diversity and genealogical history of its natural populations. Here, using a sampling design that included populations covering most of its distributional range, we investigated the spatial distribution of genetic variability of this species, and we tested the hypothesis that P. bicolor is composed of deeply structured genetic groups, constituting more than one lineage across the Brazilian Amazonia. The results suggested two main lineages in two geographic mega-regions: Western and Eastern Amazonia, the latter consisting of three population groups distributed in the Guiana and Brazilian Shields. The present findings have implications to taxonomy, to understanding the processes that lead to diversification, and to defining strategies of conservation and medicinal use of the species.

Redescription of Hepatozoon ameivae (Carini and Rudolph, 1912) from the lizard Ameiva ameiva (Linnaeus, 1758)

Blood samples from 72 Ameiva ameiva lizards from Central Amazonian upland forests were collected, and thin smears of 40 (55.5%) animals were positive for gamonts of Hepatozoon with a mean level of intensity of infection of 14 parasites/2000 blood erythrocytes (0.73%). The gametocytes were found attached with host cells' nuclei, and their dimensions were 14.28 ± 1.05 μm in length and 4.50 ± 0.80 μm in width. Phylogenetic analyses of the 18S rRNA gene showed that the new sequences obtained from A. ameiva constitute a monophyletic sister clade to the Hepatozoon spp. from Brazilian snakes. Based on morphological features and new molecular data, we redescribe this hemogregarine as Hepatozoon ameivae. This study also provides the first molecular characterization of a Hepatozoon species from a Brazilian lizard.

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.

"Bad things come in small packages": predicting venom-induced coagulopathy in Bothrops atrox bites using snake ontogenetic parameters

Introduction: Snake venom composition shows significant inter- and intra-species variation. In the case of the viperid species Bothrops atrox, responsible for the majority of snakebites in the Amazon region, geographical and ontogenetic variables affect venom composition, with ecological and medical implications. Previous studies had shown that venom from neonate and juvenile Bothrops specimens have a higher in vitro coagulant activity. The aim of this investigation was to assess the association of clinical outcomes, such as venom-induced coagulopathy and local complications, with B. atrox ontogenetic variables.Methods: This study explored the relationship between some clinical parameters in patients suffering envenomations by B. atrox in the Amazon and several morphometric parameters of the snake specimens causing the bites.Results: There were 248 specimens confirmed as agents of envenomation, mostly female snakes (70.5%) and classified as juveniles (62.7%). Patients bitten by neonates compared to adult snakes [OR = 2.70 (95%CI 1.15-6.37); p = .021] and by snakes with white tail tip [OR = 1.98 (95%CI 1.15-3.41); p = .013] were more likely to develop coagulopathy. Time from patient admission to the unclottable blood reversion was not affected by the snake gender (p = .214) or age (p = .254). Patients bitten by neonate (p = .024) or juvenile snakes (p < .0001) presented a lower frequency of moderate to severe edema, as compared to those bitten by adult snakes. In agreement with experimental observations, patients bitten by neonates and by snakes with a white tail tip were more likely to develop coagulopathy than those bitten by adult snakes. In contrast, envenomations by adult snakes were associated with a higher incidence of severe local edema.Conclusion: Despite these variations, no difference was observed in the time needed to recover blood clotting in these patients after Bothrops antivenom administration.

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 ¼ 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.

Corrigenda: A new species of Pristimantis from eastern Brazilian Amazonia (Anura, Craugastoridae). ZooKeys 687: 101-129 (2017). https://doi.org/10.3897/zookeys.687.13221

[This corrects the article DOI: 10.3897/zookeys.687.13221.].

A new species of Scinax from the Purus-Madeira interfluve, Brazilian Amazonia (Anura, Hylidae)

A new tree frog species of the genus Scinax from the interfluve between the Purus and Madeira rivers, Brazilian Amazonia, is described and illustrated. The new species is diagnosed by medium body size, snout truncate in dorsal view, ulnar and tarsal tubercles absent, nuptial pads poorly developed, skin on dorsum shagreen, dorsum light brown with dark brown spots and markings, white groin with black spots, anterior and posterior surfaces of thighs black, and iris bright orange. The advertisement call consists of a single short note, with 16-18 pulses and dominant frequency at 1572-1594 Hz. Tadpoles are characterized by body ovoid in dorsal view and triangular in lateral view, tail higher than body, oral disc located anteroventrally and laterally emarginated, dorsum of body uniformly grey-brown with dark brown eye-snout stripe in preservative, fins translucent with small to large irregular diffuse dark brown spots.

A new species of Pristimantis from eastern Brazilian Amazonia (Anura, Craugastoridae)

In this study a new species of Pristimantis (Anura: Craugastoridae) of the P. conspicillatus species group is described. Pristimantis latrosp. n. is known only from the municipalities of Altamira, Anapu, Brasil Novo, Medicilândia, Uruará and Aveiro (Flona Tapajós, right bank of Tapajós river), in Pará state, Brazil. Morphologically, the new species distinguishes from known congeners in the group mainly by the presence of dorsal tubercles and absence of discoidal folds, smooth belly skin, as well as the presence of supernumerary tubercles on hands. The call of the new species consists of seven ascending notes, the first of which has a dominant frequency of 2635 Hz and the last 3272 Hz. Molecular analysis of the 16S mtDNA indicates a genetic distance of 8% to P. chiastonotus, its closet relative, and between 9% and 11% to populations of P. fenestratus.

A new species of Allobates (Anura: Aromobatidae) from Parque Nacional da Amazônia, Pará State, Brazil

We describe the fourth species of nurse-frog genus Allobates occurring in the southeastern Brazilian Amazonia. The new species is sympatric with Allobates femoralis, Allobates masniger and Allobates magnussoni, and inhabits the margins of streams in forested areas within Parque Nacional da Amazônia, on the western bank of the Tapajós River. Snout-to-vent length ranges between 14.9-16.1 mm among males and 15.6-16.5 mm among females. The species is distinguished by the light brown background color of dorsum, with irregular dark brown blotches appearing from eye level to the urostyle region. In life, ventral surfaces of males are golden yellow on throat and chest, and white to yellow on abdomen. Ventral surfaces of females are predominantly white, except for light yellow on chin. The dark brown lateral band has a diffuse lower edge ventrolaterally. Dorsal surface of thigh is cream, with a longitudinal dark brown band extending dorsally from vent to knee. Tail musculature of tadpoles is robust, bifurcating dorsally over the body and reaching about two-thirds of the body length. Advertisement calls consist predominantly of continuous pairs of notes, but other note arrangements are also emitted. Notes have ascending frequency modulation and average peak frequency ranging between 5.3-5.9 kHz. First and second notes of the same note pair are similar in amplitude, duration and frequency spectrum. Successive note pairs are split by approximately regular silent intervals (0.30-0.49 s). The species lays its eggs inside rolled or folded dead leaves on the leaf litter. Egg capsules and jelly nests are opaque.

A new species of Allobates (Anura: Aromobatidae) from the Tapajós River basin, Pará State, Brazil

We describe a new species of Allobates from the south of eastern Amazonia, Brazil. This species inhabits fluvial springs and the banks of small streams in terra-firme forests along the Tapajós River basin. Average snout-to-vent length is 17.78 mm (range 16.09-19.59 mm) among males and 19.50 mm (range 17.97-20.84 mm) among females. Surface of dorsum is marked by a distinct dark color pattern, with three convex areas, triangle and diamond-shaped. The species has a diffuse pale dorsolateral line (absent in some specimens), while the oblique lateral bar is defined. Dark-brown transversal stripes are present on femoral and tibial dorsal surfaces, which align with each other in live specimens when at rest. Tadpoles have short papillae on anterior (8-10 papillae on each side) and posterior labium (&gt;30 papillae). Posterior labium is projected to the front, hiding posterior tooth rows. Eggs are deposited in nests on rolled or cranked dead leaves on the forest floor. Egg membranes and jelly-nests are transparent. Advertisement calls are mainly characterized by the continuous emission of single notes that might shift sporadically to note-pairs, emitted during short periods. Notes are split by regular silent intervals, with peak frequency ranging between 4273-4867 Hz. 

Distribution extension of Hyalinobatrachium cappellei (van Lidth de Jeude, 1904) (Anura: Centrolenidae) across Central Amazonia

We report the occurrence of the centrolenid frog Hyalinobatrachium cappellei in Careiro, Amazonas, Brazil (Central Amazonia). Our records reduce a gap of approximately 1,500 km between the closest known records for this glassfrog, and confirm H. cappellei as geographically widespread in the Amazon Basin.

Sexual signals of the Amazonian frog Allobates paleovarzensis: geographic variation and stereotypy of acoustic traits

Abstract

Because of its close relationship with the process of evolutionary differentiation, it is expected that geographic variability in acoustic sexual traits should be greater among than within populations. This is particularly expected in organisms with typically high population genetic structure and low dispersal abilities, such as anuran amphibians. We studied the acoustic traits of the advertisement call in the small-sized dendrobatoid frog Allobates paleovarzensisthrough its range in Central Amazonia. We accessed the variability of call traits from the within-male to the among-population levels, and evaluated the degree of stereotypy of the call characteristics. Call variability had comparable magnitudes within and among populations, and was independent of the degree of stereotypy of call measurements. Therefore, none of the call traits stood out as a potential cue for discrimination between populations. Spectral call measurements were static and strongly related with body size, which explained between 30 and 35% of the variation of these acoustic traits. Temporal characters of the notes were dynamic and influenced by environmental temperature (e.g., 27% of note rate variation), whilst temporal measurements of the entire calls were not related to the co-factors analysed. Both spectral and temporal call traits varied among populations and between sides of the Amazon River. Our results also indicate that body size and sampling site jointly affected the variability of the call traits. However, geographic distances among populations and the river barrier had no significant effect on the overall acoustic variation, indicating that local stabilising selective forces may be important in the process of call differentiation.