Activity and habitat use of two species of stingrays (Myliobatiformes: Potamotrygonidae) in the upper Paraná River basin, Southeastern Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Considerações sobre a reprodução de duas espécies de raias (Myliobatiformes, Potamotrygonidae) na região do Alto Rio Paraná, Sudeste do Brasil

This article presents preliminary information about the reproduction of two species of freshwater stingrays of the genus Potamotrygon, found in the Upper Parana River (Southwest Brazil), where these animals are exotic. Males of P. motoro and P. falkneri become sexually mature around 270 mm and 260 mm of disc width (DW), respectively. Females become sexually mature around 330 mm of DW in P. motoro and 325 mm in P. falkneri. In both species, females are bigger and heavier than males, reaching about 700 mm of DW and 20 kg. Copulating has not been recorded, but one courtship ritual has been observed during the dry season. Mature males present a different dentition from females and young males, which is probably related to their reproductive behavior instead of to their feeding habit. The female fertility has varied from one to three offspring. A miscarriage has been observed at different stages of embryonic development always when pregnant females were captured. In spite of the great history of anthropization of the study area, it seems that hydrological cycles are related to the reproduction of stingrays. Nevertheless, it would be necessary to conduct deeper studies to verify or not this influence.

Impacto das arraias (Myliobatiformes: Potamotrygonidae) na população ribeirinha e demais frequentadores do alto curso do Rio Paraná e alguns afluentes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudos citogenéticos em raias do gênero Patamotrygon (Chondrichthyes: Myliobatiformes: Potamotrygonidae) na bacia superior do rio Paraná

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Variáveis hematológicas, hormonais, bioquímicas séricas e fauna parasitária em quatro espécies de raias do gênero Potamotrygon Garman, 1877 (Myliobatiformes, Potamotrygonidae) de vida livre

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A test of the utility of DNA barcoding in the radiation of the freshwater stingray genus Potamotrygon (Potamotrygonidae, Myliobatiformes)

DNA barcoding is a recently proposed global standard in taxonomy based on DNA sequences. The two main goals of DNA barcoding methodology are assignment of specimens to a species and discovery of new species. There are two main underlying assumptions: i) reciprocal monophyly of species, and ii) intraspecific divergence is always less than interspecific divergence. Here we present a phylogenetic analysis of the family Potamotrygonidae based on mitochondrial cytochrome c oxidase I gene, sampling 10 out of the 18 to 20 valid species including two non-described species. Potamotrygonidae systematics is still not fully resolved with several still-to-be-described species while some other species are difficult to delimit due to overlap in morphological characters and because of sharing a complex color patterns. Our results suggest that the family passed through a process of rapid speciation and that the species Potamotrygon motoro, P. scobina, and P. orbignyi share haplotypes extensively. Our results suggest that systems of identification of specimens based on DNA sequences, together with morphological and/or ecological characters, can aid taxonomic studies, but delimitation of new species based on threshold values of genetic distances are overly simplistic and misleading.

Taxonomia, biologia reprodutiva e dieta da Raia Borboleta, Gymnura micrura (Myliobatiformes: Elasmobranchii)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudos genéticos em raias do gênero Potamotrygon (Chondrichthyes: Myliobatiformes: Potamotrygonidae) na Bacia do Rio Paraná

Pós-graduação em Ciências Biológicas (Zoologia) - IBB

First identification of interspecies hybridization in the freshwater stingrays Potamotrygon motoro and P-falkneri (Myliobatiformes, Potamotrygonidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Morphology and phylogenetic relationships of a remarkable new genus and two new species of Neotropical freshwater stingrays from the Amazon basin (Chondrichthyes: Potamotrygonidae)

The morphology and phylogenetic relationships of a new genus and two new species of Neotropical freshwater stingrays, family Potamotrygonidae, are investigated and described in detail. The new genus, Heliotrygon, n. gen., and its two new species, Heliotrygon gomesi, n. sp. (type-species) and Heliotrygon rosai, n. sp., are compared to all genera and species of potamotrygonids, based on revisions in progress. Some of the derived features of Heliotrygon include its unique disc proportions (disc highly circular, convex anteriorly at snout region, its width and length very similar), extreme subdivision of suborbital canal (forming a complex honeycomb-like pattern anterolaterally on disc), stout and triangular pelvic girdle, extremely reduced caudal sting, basibranchial copula with very slender and acute anterior extension, and precerebral and frontoparietal fontanellae of about equal width, tapering very little posteriorly. Both new species can be distinguished by their unique color patterns: Heliotrygon gomesi is uniform gray to light tan or brownish dorsally, without distinct patterns, whereas Heliotrygon rosai is characterized by numerous white to creamy-white vermiculate markings over a light brown, tan or gray background color. Additional proportional characters that may further distinguish both species are also discussed. Morphological descriptions are provided for dermal denticles, ventral lateral-line canals, skeleton, and cranial, hyoid and mandibular muscles of Heliotrygon, which clearly corroborate it as the sister group of Paratrygon. Both genera share numerous derived features of the ventral lateral-line canals, neurocranium, scapulocoracoid, pectoral basals, clasper morphology, and specific patterns of the adductor mandibulae and spiracularis medialis muscles. Potamotrygon and Plesiotrygon are demonstrated to share derived characters of their ventral lateral-line canals, in addition to the presence of angular cartilages. Our morphological phylogeny is further corroborated by a molecular phylogenetic analysis of cytochrome b based on four sequences (637 base pairs in length), representing two distinct haplotypes for Heliotrygon gomesi. Parsimony analysis produced a single most parsimonious tree revealing Heliotrygon and Paratrygon as sister taxa (boot-strap proportion of 70%), which together are the sister group to a clade including Plesiotrygon and species of Potamotrygon. These unusual stingrays highlight that potamotrygonid diversity, both in terms of species composition and undetected morphological and molecular patterns, is still poorly known.

Potamotrygon tigrina, a new species of freshwater stingray from the upper Amazon basin, closely related to Potamotrygon schroederi Fernandez-Yepez, 1958 (Chondrichthyes: Potamotrygonidae)

A new species of Neotropical freshwater stingray, family Potamotrygonidae, is described from the Rio Nanay in the upper Rio Amazonas basin of Peru. Potamotrygon tigrina, n. sp., is easily distinguished from all congeners by its conspicuous dorsal disc coloration, composed of bright yellow to orange vermiculations strongly interwoven with a dark-brown to deep-black background. Additional features that in combination diagnose P. tigrina, n. sp., include the presence of a single angular cartilage, low and not closely grouped dorsal tail spines, and coloration of tail composed of relatively wide and alternating bands of creamy white and dark brown to black. Potamotrygon tigrina is closely related to Potamotrygon schroederi Fernandez-Yepez, 1958, which occurs in the Rio Negro (Brazil) and Rio Orinoco (Venezuela, Colombia). Both species are very similar in proportions and counts, and share features hypothesized to be derived within Potamotrygonidae, related to their specific angular cartilage morphology, distal tail color, dorsal tail-spine pattern, and ventral lateral-line system. To further substantiate the description of P. tigrina, n. sp., we provide a redescription of P. schroederi based on material from the Rio Negro (Brazil) and Rio Orinoco (Venezuela). Specimens from the two basins differ in number of vertebral centra and slightly in size and frequency of rosettes on dorsal disc, distinctions that presently do not warrant their specific separation. Potamotrygon tigrina is frequently commercialized in the international aquarium trade but virtually nothing is known of its biology or conservation status.

Reproductive biology of the smooth butterfly ray Gymnura micrura

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Reproductive biology of the smooth butterfly ray Gymnura micrura

This study provides the first detailed information on the reproductive biology of the smooth butterfly ray Gymnura micrura. A total of 905 individuals were sampled, 377 of which were used for the reproductive study. Juveniles accounted for 75% of the sample, but all life cycle stages were present in the study area. The disc width at which 50% were mature (WD50)was estimated at 269 and 405 mm for males and females, respectively. The WD50V(based on the onset of vitellogenesis) was estimated at 359 mm. Uterine fecundity (mean +/- s.d. = 3.8 +/- 1.3; range: 16) was positively correlated with female size. A 3564% gain in mean wet mass was observed from egg to full-term embryo in utero. Size at birth ranged from 135 to 175 mm WD (19.5 to 55.0 g), with a mean of 165.1 mm WD (43.3 g). The embryo sex ratio was not significantly different from 1:1. The ovaries of pregnant females were undergoing vitellogenesis during gestation, with females ready to ovulate soon after parturition. Gymnura micrura may have an asynchronous reproductive cycle, with females reproducing continuously throughout the year.

Seláceos do Farol das Lagostas (Bacia do Cuanza, Angola)

O presente trabalho consiste na apresentação da diversidade de seláceos do Farol das Lagostas pertencente à Bacia do Cuanza. Os condrichthyes são componentes comuns da fauna aquática desde o Paleozoico. No entanto, devido à natureza cartilaginosa do esqueleto, o registo paleontológico dos mesmos restringe-se, basicamente, às partes mineralizadas como dentes, dentículos dérmicos e espinhas cefálicas O lugar Farol das Lagostas contém uma fauna de seláceos relativamente rica e variada, representada neste estudo por cerca de 1.000 dentes isolados, além de outras peças esqueléticas. Foram identificados e descritos quarenta e quatro taxa, pertencentes às seguintes ordens: Hexanchiformes, Squaliformes, Pristiophoriformes, Squatiniformes, Lamniformes, Carcharhiniformes, Rajiformes e Myliobatiformes. Trata-se de uma diversidade faunística cuja maioria dos géneros possui representantes atuais. Os Carcharhiniformes representam 53% dos taxa identificados. Estão representadas as famílias Scyliorhinidae, Triakidae, Hemigaleidae, Carcharhinidae e Sphyrnidae, com 18 espécies. Verifica-se a presença de formas bentónicas e nectónicas que indicam condições térmicas moderadas, quentes e tropicais a temperadas, que habitam frequentemente zonas costeiras. A relação faunística identificada corresponde a uma zona litoral. Ora, considerando o conjunto de dados em face da presença de fauna pelágica e dos grandes predadores, especialmente Isurus hastalis e Carcharocles megalodon, podemos admitir que existisse então um Golfo relativamente largo de uma faixa Atlântica aberta (Antunes & Balbino, 2004); ABSTRACT: Selachians from Farol the Lagostas (Cuanza Basin, Angola) The present work consists of the presentation of diversity of selachians from Farol das Lagostas, which belongs to the Cuanza Basin. The condrichthyes are a part of aquatic fauna since the Paleozoic. However, due to the nature of the cartilaginous skeleton, the paleontological registration of the same ones is restricted to mineralized parts like teeth, dermal denticles and cephalic spines. The of formation, Farol das Lagostas has a fauna of selachian relatively rich and diverse, represented in this study for around 1.000 isolated teeth, and other skeletal parts. Forty four taxa were described and identified, belonging to the following orders: Hexanchiformes, Squaliformes, Pristiophoriformes, Squatiniformes, Lamniformes, Carcharhiniformes, Rajiformes e Myliobatiformes. It’s a faunal diversity whose most genera have current representatives. The Carcharhiniformes represente 53% of the identified taxa. The represented families are Scyliorhinidae, Triakidae, Hemigaleidae, Carcharhinidae e Sphyrnidae, with 18 species. There is presence of benthic and nektonic forms that indicate moderate thermal conditions, the temperate and tropical hot, often inhabit coastal areas. The identified faunal relation corresponds to a coastal zone. So, considering the data set, due to the presence of pelagic fauna and large predators, especially Isurus hastalis e Carcharocles megalodon, we can admit that then there was a relatively large Gulf of open Atlantic range (Antunes & Balbino, 2004).

Seláceos do Langhiano da Bacia do Baixo Tejo (Brielas Portugal)

O afloramento de Brielas, costa de Caparica (Miocénico Médio) apresenta uma elevada riqueza especifica representada neste estudo por 671 dentes isolados, 11 dentículos dérmicos e 4 fragmentos de aguilhão. Foram identificados e descritos quarenta seis taxa pertencentes as seguintes ordens: Carcharhiniformes,Myliobatiformes, Hexanchiformes, Lamniformes, Rajiformes, Squatiniformes e Torpediniformes. Trata-se de uma fauna cuja maioria dos géneros possuem representantes actuais e onde se encontram, inclusivamente,algumas espécies que existem actualmente no território marítimo português. Descreve-se pela primeira vez no registo f6ssil português Torpedo torpedo, e o género Mustelus é descrito em idade mais antiga que a da primeira referencia deste género em Portugal. Verifica-se a presença de formas bentónicas e nectónicas de águas quentes tropicais a temperadas, que habitariam frequentemente zonas costeiras; é de notar a presença de certas formas em detrimento de outras, reforçando as conclusões de investigadores anteriores.