Envenomations caused by fish in Brazil: an evolutionary, morphological, and clinical vision of a neglected problem

ABSTRACT Venomous fish are commonly found in Brazilian waters. The most important marine venomous fish species are stingrays (Dasyatidae, Gimnuridae, Myliobatidae, and Rhinopteridae families), catfish (Ariidae family), scorpionfish and lionfish (both Scorpaenidae family), and toadfish (Batrachoididae family). Meanwhile, Potamotrygonidae stingrays and Pimelodidae catfish are the most important venomous freshwater fish. The mechanisms of envenomation vary and involve various venomous apparatuses and glands. Despite not being highly developed, these venomous apparatuses in fish appear rudimentary, using structures such as fins and rays to inoculate toxins and rarely presenting with specialized structures. Toxins are produced by glandular tissue made up of proteinaceous cells, lacking true glands, and are positioned along the inoculation structures. However, systemic manifestations are rare. No antivenom serum has been developed for any species of American venomous fish. Brazilian venomous fish and their venoms have only recently attracted attention, leading to new studies not only addressing clinical issues in humans, but also exploring the discovery of new active substances with immense pharmacological potential.

Mapping of the venomous stingrays of the Potamotrygon genus in the Tietê River, São Paulo Sstate, Brazil

ABSTRACT Background: Freshwater stingrays are fish that have adapted to the rivers and lakes in South America. The expansion of the Potamotrygonidae family in the Paraná River began after the damming of the Sete Quedas Falls, reaching the mouth of the Paranapanema and Tietê rivers approximately 20 years ago via the locks of the hydroelectric power plants. They are not aggressive animals; however, they have one to four stingers on their tails covered by a venom-producing epithelium and can cause severe envenomation in fishermen and bathers if stepped on or manipulated. Methods: We conducted a descriptive, retrospective, and prospective study by monitoring the fishing of the Potamotrygon genus in the lower Tietê River, mapping the location of the rays as a fishery product of professional fishermen and/or recording images of the fish caught. Results: Sixteen stingrays of the Potamotrygon genus were mapped by monitoring fishermen's fish products in the extensive area between the municipalities of Pereira Barreto and Buritama, São Paulo state. Conclusions: The lower Tietê River is fully colonized by freshwater stingrays and this expansion likely continues upstream, reaching various sub-basins of the river. The advancement of these venomous fish in areas where they did not exist previously requires education programs and interaction with the community to avoid serious injuries in bathers and fishermen and the unreasonable extermination of the animals.

Two new species of freshwater stingrays of the genus Paratrygon (Chondrichthyes: Potamotrygonidae) from the Orinoco basin, with comments on the taxonomy of Paratrygon aiereba

The genus Paratrygon, currently recognized as the sole monotypic genus of the family Potamotrygonidae, has a considerably greater diversity than previously indicated, including molecular studies, which supported P. aiereba (hitherto the only recognized species in the genus) as a possible species complex. Here we describe two new species of the genus that are both endemic to and sympatric in the Orinoco basin. Paratrygon aiereba, type species of the genus, is now restricted to the Amazon basin. Both new species are identified and defined through morphological characters such as coloration, dermal denticle morphology, arrangement of thorns, distribution and morphology of ventral lateral line canals, morphology of skeletal elements, and morphometrics. An extensive comparison of these characters between the new species herein described and P. aiereba is presented. Finally, a taxonomic reappraisal of P. aiereba is provided through a revision of preserved material and its original description, plus new evidence about its type-locatity, collectors, and a reconsideration of the destination of its type-specimen.(AU)

O gênero Paratrygon, reconhecido atualmente como o único gênero monotípico da família Potamotrygonidae, possui uma considerável alta diversidade do que previamente indicado, incluindo estudos moleculares, que corroboravam P. aiereba (a única espécie reconhecida para o gênero até então) como um possível complexo de espécies. Aqui descrevemos duas novas espécies do gênero para a bacia do Orinoco, ambas endêmicas e simpátricas para esta bacia. Paratrygon aiereba, espécie tipo do gênero, agora está restrita para a bacia Amazônica. Ambas novas espécies são identificadas e definidas através de caracteres morfológicos tais como coloração, morfologia dos dentículos dérmicos, arranjo dos espinhos pontiagudos, distribuição e morfologia dos canais ventrais da linha lateral, morfologia dos elementos do esqueleto e morfometria. Uma comparação extensiva destes caracteres entre as novas espécies aqui descritas e P. aiereba é apresentada. Finalmente uma reavaliação taxonômica de P. aiereba é fornecida através da revisão de espécimes preservados e de sua descrição original, além de novas evidências sobre sua possível localidade-tipo, coletores, e uma reconsideração do destino de seu espécime-tipo.(AU)

Accident and vascular injury with stingray in the Alto Juruá, Acre, Brazil: a case report / Acidente e lesão vascular com arraia no Alto Juruá, Acre, Brasil: um relato de caso

INTRODUCTION: Injuries caused by fish are common and considered a neglected health problem with high morbidity and low lethality. Noteworthy are the envenomings by freshwater stingrays, which are considered very serious and one of the most important injuries caused by aquatic animals in South America. CASE PRESENTATION: To describe an accident and vascular injury with venomous stingray animals in the Alto do Juruá, Acre, Brazil. Male patient admitted due to stingray in the left lower extremity 20 days ago. CONCLUSION: The freshwater stingray, due to its sharp characteristics, injured the great saphenous vein, requiring surgical intervention. The situation presented negative evolution due to the lack of necessary procedures in the first attendance, such as the proper cleaning of the wound and the removal of the sting.

INTRODUÇÃO: Acidentes com peixes, denominados de ictismo, são comuns e são considerados um problema de saúde negligenciado, de alta morbidade e baixa letalidade. Destacam-se os envenenamentos por arraias de água doce, pois são considerados muito graves e uma das mais importantes lesões causadas por animais aquáticos na América do Sul. APRESENTAÇÃO DO CASO: Descrever um acidente e lesão vascular com animais peçonhentos do tipo arraia no alto do Juruá, Acre, Brasil. Paciente do sexo masculino, admitido devido a ferroada de arraia no membro inferior esquerda há 20 dias. CONCLUSÃO: O ferrão da arraia de água doce por possuir características pontiagudas lesionou a veia safena magna, necessitando de uma intervenção cirúrgica. O quadro apresentou evolução negativa devido a não realização de procedimentos necessários no primeiro atendimento, como a limpeza adequada do ferimento e a retirada do ferrão.

Injuries caused by freshwater stingrays in the Tapajós River Basin: a clinical and sociodemographic study

Abstract INTRODUCTION Freshwater stingray envenomations are an important cause of morbidity in riverine populations living in various regions of Brazil. The sequelae include temporary or permanent disability. This study aimed to identify sociodemographic, clinical, and therapeutic aspects related to stingray injuries in such populations. METHODS This cross-sectional study was conducted in the Extractive Reserve of Tapajos-Arapiuns, located in the municipalities of Santarém and Aveiro (Pará State). A convenience sample comprising 300 local adults was used to obtain data by means of a questionnaire/ interview. RESULTS Overall, 19 (6.3%) participants reported having sustained a stingray injury in the 12 months prior to the study. All 19 were injured either while fishing (n=13 [68.4%]) or engaging in other riverine activities. Most injuries [n=14 (73.7%)] occurred from September through November, and most injured respondents [n=15 (78.9%)] reported seeing stingrays at beaches. Severe pain and the appearance of ulcers in the later stages of envenomation were described by 18 (94.7%) and 12 (63.2%) participants, respectively. CONCLUSIONS Freshwater stingray injuries, which should be considered occupational injuries, are common in the study area, especially in places like beaches or in the lakes that form during the dry season, when stingrays are routinely observed. A significant proportion of respondents was unaware of the correct first aid measures and had insufficient resources to treat the complications of these injuries in the locality where they reside. Interactive activities involving local residents - such as lectures and the distribution of simple pamphlets providing information about stingray injuries - are needed.

Injuries by marine and freshwater stingrays: history, clinical aspects of the envenomations and current status of a neglected problem in Brazil

Stingrays are a group of rays – cartilaginous fish related to sharks – that have whiplike tails with barbed, usually venomous spines and are found around the world, especially the marine species. Despite recent reports of accidents involving these fish, they are not aggressive, reacting only when stepped on or improperly handled. Injuries by stingrays are seldom mentioned by historians, although they have always been present in riverine communities of inland waters and in South American coasts. Indeed, envenomations by stingrays are quite common in freshwater and marine fishing communities. Although having high morbidity, such injuries are neglected because they have low lethality and usually occur in remote areas, which favor the use of folk remedies. In the present review article, historical aspects of injuries caused by stingrays in Brazil and their distribution on the coast of São Paulo state and riverine communities of the North, Midwest and Southeast regions were studied. In addition, other aspects were analyzed such as clinical features, therapeutic methods, preventive measures and trends in occurrence of these accidents in the country, particularly in areas in which freshwater stingrays had not been previously registered, being introduced after breaching of natural barriers.

Injuries by marine and freshwater stingrays: history, clinical aspects of the envenomations and current status of a neglected problem in Brazil

Stingrays are a group of rays – cartilaginous fish related to sharks – that have whiplike tails with barbed, usually venomous spines and are found around the world, especially the marine species. Despite recent reports of accidents involving these fish, they are not aggressive, reacting only when stepped on or improperly handled. Injuries by stingrays are seldom mentioned by historians, although they have always been present in riverine communities of inland waters and in South American coasts. Indeed, envenomations by stingrays are quite common in freshwater and marine fishing communities. Although having high morbidity, such injuries are neglected because they have low lethality and usually occur in remote areas, which favor the use of folk remedies. In the present review article, historical aspects of injuries caused by stingrays in Brazil and their distribution on the coast of São Paulo state and riverine communities of the North, Midwest and Southeast regions were studied. In addition, other aspects were analyzed such as clinical features, therapeutic methods, preventive measures and trends in occurrence of these accidents in the country, particularly in areas in which freshwater stingrays had not been previously registered, being introduced after breaching of natural barriers.

Injuries by marine and freshwater stingrays: history, clinical aspects of the envenomations and current status of a neglected problem in Brazil

Stingrays are a group of rays - cartilaginous fish related to sharks - that have whiplike tails with barbed, usually venomous spines and are found around the world, especially the marine species. Despite recent reports of accidents involving these fish, they are not aggressive, reacting only when stepped on or improperly handled. Injuries by stingrays are seldom mentioned by historians, although they have always been present in riverine communities of inland waters and in South American coasts. Indeed, envenomations by stingrays are quite common in freshwater and marine fishing communities. Although having high morbidity, such injuries are neglected because they have low lethality and usually occur in remote areas, which favor the use of folk remedies. In the present review article, historical aspects of injuries caused by stingrays in Brazil and their distribution on the coast of São Paulo state and riverine communities of the North, Midwest and Southeast regions were studied. In addition, other aspects were analyzed such as clinical features, therapeutic methods, preventive measures and trends in occurrence of these accidents in the country, particularly in areas in which freshwater stingrays had not been previously registered, being introduced after breaching of natural barriers.(AU)

Catfishes as prey items of Potamotrygonid stingrays in the Solimões and Negro rivers, Brazilian Amazon / Os bagres como presas de raias Potamotrygonidae nos rios Solimões e Negro, Amazônia brasileira

In spite of the fact that catfish have rarely been reported as food items in the diets of freshwater stingrays, they are commonly observed in the stomach contents of species inhabiting the Solimões and Negro rivers in the Brazilian Amazon. The stomach contents of six rays from the Solimões River and 64 from the Negro River were analyzed, and catfishes (distributed among the families Callichthyidae, Cetopsidae, Doradidae and Loricariidae) were found in the stomach contents of four and 10 of these rays, respectively, comprising a frequency of occurrence of 20%. These data indicate a relevant participation of catfishes in the diets of potamotrygonid rays in the Amazon, and may reflect the regional diversity and abundance of Siluriformes in the region.

Apesar de ter sido reportado sobre a raridade de bagres na alimentação de raias de água doce, a presença deles tem sido comumente observada em conteúdos estomacais de espécies dos rios Solimões e Negro. Os conteúdos estomacais de seis indivíduos de raias do rio Solimões e 64 do rio Negro foram analisados e os bagres (distribuídos nas famílias Callichthyidae, Cetopsidae, Doradidae e Loricariidae) foram consumidos por quatro e 10 raias, respectivamente, com a frequência de ocorrência de 20%. A ocorrência de Siluriformes, mesmo baixa, indica uma participação relevante deste grupo como presas na dieta dos potamotrigonídeos.

Systematic revision of the Potamotrygon motoro (Müller & Henle, 1841) species complex in the Paraná-Paraguay basin, with description of two new ocellated species (Chondrichthyes: Myliobatiformes: Potamotrygonidae)

A systematic revision of the Potamotrygon motoro (Müller & Henle, 1841) species complex in the Paraná-Paraguay basin based on morphological characters was undertaken. Morphological systems analyzed include external morphology, coloration, dermal denticles, and spines, canals of the ventral lateral-line system, and skeletal components. Potamotrygon motoro is widely distributed in the Paraná-Paraguay basin and some of its diagnostic characters are: ocelli present on dorsal disc tricolored, well-defined and evenly distributed, with diameter similar or greater than eye-length; ventral coloration with relatively large whitish central region, with gray or brown area predominant on outer ventral disc margins; dermal denticles well-developed and star-shaped over central disc; labial grooves absent; monognathic heterodonty present in upper and lower jaws of adults. Potamotrygon pauckei Castex, 1963 and Potamotrygon labradori Castex, Maciel & Achenbach, 1963, are synonymized with P. motoro; Potamotrygon alba Castex, 1963, is a nomen dubium in accordance with previous authors. Additionally, two new ocellated species of Potamotrygon from the Paraná-Paraguay basin are described: Potamotrygon pantanensis, sp. nov. and Potamotrygon amandae, sp. nov. These are described and compared with P. motoro and other congeners. Potamotrygon pantanensis, sp. nov. is described from the northern Pantanal region; Potamotrygon amandae, sp. nov. is widespread in the Paraná-Paraguay basin.

Uma revisão sistemática do complexo de espécies Potamotrygon motoro (Müller & Henle, 1841) na bacia Paraná-Paraguai, baseada em caracteres morfológicos, foi realizada. Os caracteres morfológicos analisados incluem morfologia externa, coloração, dentículos dérmicos e espinhos, sistema de canais ventrais da linha lateral e componentes do esqueleto. Potamotrygon motoro é amplamente distribuída na bacia Paraná-Paraguai e alguns dos seus caracteres diagnósticos são: ocelos presentes no dorso do disco tricolores, bem definidos e bem distribuídos, com diâmetro similar ou maior do que o comprimento do olho; coloração ventral com região central do disco branca e com tonalidades marrom ou cinza presentes nas margens do disco; dentículos dérmicos bem desenvolvidos e com formato estrelado na região central do disco; sulcos labiais ausentes; heterodontia monognática presente nas maxilas superior e inferior nos adultos. Potamotrygon pauckei Castex, 1963 e Potamotrygon labradori Castex, Maciel & Achenbach, 1963, são sinonimizadas com P. motoro, e Potamotrygon alba Castex, 1963, é considerada um nomen dubium em acordo com autores anteriores. Além disso, duas espécies novas oceladas de Potamotrygon da bacia Paraná-Paraguai são descritas: Potamotrygon pantanensis, sp. nov. e Potamotrygon amandae, sp. nov. Estas espécies novas são descritas e comparadas com P. motoro e outras espécies do gênero. Potamotrygon pantanensis, sp. nov. é descrita da região norte do Pantanal e Potamotrygon amandae, sp. nov. é amplamente distribuída na bacia Paraná-Paraguai.

Karyotype description and evidence of multiple sex chromosome system X1X1X2X2/X1X2Y in Potamotrygon aff. motoro and P. falkneri (Chondrichthyes: Potamotrygonidae) in the upper Paraná River basin, Brazil

Análises citogenéticas de Potamotrygon aff. motoro e P. falkneri identificaram a ocorrência de um sistema múltiplo de cromossomos sexuais do tipo X1X1X2X2/X1X2Y, em ambas as espécies, com 2n = 66 cromossomos em fêmeas e 2n = 65 cromossomos nos machos. As regiões organizadoras de nucléolos (RONs) identificadas pela reação Ag-RON, evidenciaram marcações múltiplas em ambas as espécies (com variações de 5 a 7 RONs). A técnica de bandamento C, revelou a presença de blocos heterocromáticos localizados nas regiões centromérica em quase todos os cromossomos nas duas espécies em estudo. Através do presente estudo foi evidenciada uma heterogeneidade nos cariótipos, permitindo sugerir que rearranjos cromossômicos, como inversões e/ou translocações, ocorreram durante a evolução cromossômica nas duas espécies desse gênero.

Cytogenetic analysis of Potamotrygon aff. motoro and P. falkneri indicated the occurrence of an X1X1X2X2/X1X2Y multiple sex chromosome system in both species, with 2n = 66 chromosomes for females and 2n = 65 chromosomes for males. The nucleolus organizer regions (NORs) identified using Ag-NOR technique showed that both species have multiple Ag-NORs (5 to 7 chromosomes stained). C-banding technique indicated the presence of heterochromatic blocks in the centromeric regions of almost all chromosomes in both species. Through this study there was evidence of heterogeneity in the karyotypes, which suggests that chromosomal rearrangements such as inversions and/or translocations occurred during the chromosomal evolution in two species of this genus.

A taxonomic and morphological redescription of Potamotrygon falkneri Castex & Maciel, 1963 (Chondrichthyes: Myliobatiformes: Potamotrygonidae)

Uma revisão taxonômica de duas espécies nominais de raias de água doce do gênero Potamotrygon previamente consideradas válidas, Potamotrygon falkneri Castex & Maciel, 1963 e Potamotrygon castexi Castello & Yagolkowski, 1969, foi realizada baseada numa análise detalhada abrangendo aspectos da morfologia externa e interna, incluindo um estudo morfométrico e merístico de espécimes provenientes da distribuição registrada dessas espécies. Além dessas espécies, o status taxonômico da espécie nominal Potamotrygon menchacai Achenbach, 1967, tratada por autores prévios como sinônimo júnior de Potamotrygon falkneri, foi avaliado. As espécies nominais que constituem o que foi chamado de complexo falkneri-castexi representam exemplos da variação cromática encontrados em uma única espécie, uma vez que ocorrem padrões intermediários de coloração e os caracteres restantes não são consistentes para separação em nível específico. Sendo assim, a espécie nominal P. falkneri é considerada válida e as espécies nominais P. castexi e P. menchacai sinônimos juniores desta. Adicionalmente, uma possível espécie nova é apresentada do río Madre de Dios no Peru, sendo esta portadora de alguns caracteres destoantes de P. falkneri. Essa espécie, conhecida de poucos indivíduos, é tratada aqui provisoriamente como Potamotrygon sp.

A taxonomic revision of two nominal species of freshwater stingrays of the genus Potamotrygon previously considered valid, Potamotrygon falkneri Castex & Maciel, 1963 and Potamotrygon castexi Castello & Yagolkowski, 1969, was conducted based on a detailed analysis of external and internal morphology, including a morphometric and meristic study of specimens from the recorded range of both species. The taxonomic status of the nominal species P. menchacai Achenbach, 1967, treated by previous authors as a junior synonym of P. falkneri, was also evaluated. These nominal species, which constitute what has been called the falkneri-castexi complex, were found to represent examples of chromatic variation present in a single species, given that intermediate patterns of coloration are common and the remaining characters analyzed are not consistent enough for separation at the specific level. Consequently, Potamotrygon falkneri is considered valid, whereas the nominal species Potamotrygon castexi and Potamotrygon menchacai are concluded to be junior synonyms of P. falkneri. Additionally, a putative new species is identified from the río Madre de Díos in Peru, which has some characters that do not correspond to P. falkneri. This species, known from few individuals, is here provisionally treated as Potamotrygon sp.

Arraias em rios da região Sudeste do Brasil: locais de ocorrência e impactos sobre a população / Stingrays in rivers in southeastern Brazil: occurrence localities and impact on the population

INTRODUÇÃO: No presente trabalho objetivamos descrever o processo de colonização da Bacia do Alto Paraná, Sudeste do Brasil, por arraias, demonstrando sua atual situação e provável tendência, os impactos gerados e discutindo algumas ações de manejo e medidas mitigadoras. MÉTODOS: Foram realizadas entrevistas com ribeirinhos e profissionais de saúde para o levantamento de informações sobre a ocorrência de arraias e acidentes associados a estes animais, além de coletas e observações subaquáticas de potamotrigonídeos, entre 2004 e 2009, em localidades situadas nos Estados de São Paulo, Paraná e Mato Grosso do Sul, no Sudeste, Sul e parte do Centro-Oeste do Brasil. RESULTADOS: Três espécies de arraias foram identificadas na área de estudo, demonstrando utilizar os caminhos abertos pela Hidrovia Tietê-Paraná para se dispersarem. Dezesseis vítimas de acidentes envolvendo esses animais foram encontradas, notadamente banhistas e pescadores, chamando a atenção pelo fato dos casos não serem notificados e apresentarem elevada morbidade, com marcante incapacidade temporária para o trabalho. CONCLUSÕES: Este é o primeiro relato de invasão biológica envolvendo espécies de elasmobrânquios conhecido na literatura e, pelas arraias estarem colonizando áreas densamente povoadas e ampliando sua área de distribuição a cada ano, é de se esperar que sua interação negativa com humanos se intensifique, provocando alterações importantes no perfil epidemiológico dos acidentes por animais peçonhentos ocorridos no sudeste brasileiro.

INTRODUCTION: In this paper, our aim was to describe the process of colonization of the upper Paraná basin, southeastern Brazil, by stingrays, showing the current situation, likely trend and impact caused and discussing some management actions and mitigation measures. METHODS: Interviews were held with riverbank people and health professionals, to gather information on occurrences of stingrays and accidents associated with these animals, along with underwater observations and collection of specimens, between 2004 and 2009 in localities in the States of São Paulo, Paraná and Mato Grosso do Sul, in the southeastern, southern and part of the central-western regions of Brazil. RESULTS: Three species of stingrays were identified in the study area, thus demonstrating that they were using the paths opened by the Tietê-Paraná Waterway to disperse. Sixteen victims of accidents involving these animals were found, mainly bathers and fishermen. Attention was drawn to the fact that these cases had not been reported, yet they presented high morbidity with notable temporary incapacity for work. CONCLUSIONS: This is the first report on biological invasion involving species of elasmobranchs in the literature and, because stingrays are colonizing densely populated areas and are expanding their range of distribution each year, it can be expected that their negative interactions with humans will intensify, with important changes in the epidemiological profile of accidents due to venomous animals occurring in southeastern Brazil.

Registro de ocorrência de duas espécies de potamotrigonídeos na região do Alto Rio Paraná e algumas considerações sobre sua biologia / Occurrence record of two potamotrigonids species in the Upper Paraná River and some aspects about their biology

A distribuição geográfica das raias da família Potamotrygonidae é restrita aos principais sistemas fluviais da América do Sul. No Brasil, a ocorrência de potamotrigonídeos é conhecida em toda a Bacia Amazônica, em alguns rios da região Nordeste e na Bacia Paraguai-Paraná. O alto curso do Rio Paraná, separado no passado dos trechos médio e baixo pelas Cachoeiras de Sete-Quedas, hoje está conectado a essas áreas devido ao represamento de grande parte de seu curso. A construção das barragens destruiu obstáculos naturais, possibilitando a dispersão de diversas espécies de organismos aquáticos rumo ao alto curso do Rio Paraná. Reportamos aqui o registro da ocorrência de duas espécies de raias no Alto Rio Paraná, as quais não faziam parte da fauna nativa da região há pouco mais de duas décadas atrás.

The freshwater stingrays of the Potamotrygonidae family are elasmobranchs restricted to the major river systems of South America. In Brazil, the occurrence of potamotrigonids is known in all the Amazonian Basin, some rivers of the Northeastern region and in the Paraguay-Paraná Basin. The upper course of the Paraná River, separated in the past from the medium and low courses by Sete-Quedas Waterfalls, today is connected to these areas due to the dams constructed in great part of its course. The dams had destroyed natural barriers, making possible the dispersion of many species of aquatic organisms to the headwaters of the Paraná River. We report the occurrence record of two species of stingrays in the Upper Paraná River, which were not part of native fauna about two decades ago.