Species Of Freshwater Stingray Research Articles

Diversity and ecological relationships of Cestoda and Monogenoidea parasites of freshwater stingrays (Myliobatiformes, Potamotrygonidae), in the upper Paraná River, Brazil

The Neotropical freshwater stingrays of Potamotrygon genus present a unique and complex natural history and biogeographical pattern that can be traced to a marine origin and the colonization of the continental environment during the Miocene. During the evolution of potamotrygonids, several species of the parasitic fauna coevolved and co-opted concomitantly to their hosts during the colonization of the new environments. One striking example can be observed during the colonization of the upper Paraná River region. However, few studies explored the ecological and taxonomic aspects of potamotrygonid parasites. In this work, we investigate aspects of the ecology and taxonomy of the species of Monogenea and Cestoda that are parasites the species of freshwater stingrays of the genus Potamotrygon in the upper Paraná River. Our results indicate that at least six species of parasites are present in potamotrygonids in the region. Two of the observed parasites are putative new species and three of the parasitic species were identified for the first time in the region, hence expanding their geographic distributions. We quantified ecological aspects at different levels of communities for the collected parasite species. We compared the diversity in different locations and hosts and performed an exploratory analysis to investigate the differences in parasite abundance. Additionally, an identification key for the Monogenea and Cestoda species of the sampled region is provided.

Hematological and plasma biochemical profile of two species of freshwater stingrays from the Amazon.

The evaluation of hematological and plasma biochemical parameters and the subsequent establishment of reference intervals facilitate the diagnosis of the health status of animals. This work aimed to determine the blood parameters of wild specimens of the stingrays Potamotrygon motoro and Potamotrygon orbignyi from the lower Solimões River region, Amazonas, Brazil. One hundred forty-one stingrays were captured, 92 specimens of P. motoro and 49 of P. orbignyi, of both sexes and at different stages of development. No effect of sex was observed on the blood parameters of juvenile animals for both species. P. motoro neonates presented a distinct hematological and biochemical profile, with significantly lower hematocrit values, hemoglobina, number of erythrocytes, mean corpuscular hemoglobin concentration, monocytes, plasma glucose, total proteins, albumin, and globulin. On the other hand, total cholesterol and urea levels were significantly higher in this same group compared to juveniles of the same species. Comparison between species revealed lower values of triglycerides and total cholesterol in P. orbignyi of both sexes. The results obtained are pioneering for these Amazonian species in white water environments and will serve as a basis for evaluating the health status of wild stingrays. Thus, from the analysis of the blood of the P. motoro and P. orbignyi stingrays, it was possible to observe good health conditions.

First Karyotypic Insights into Potamotrygon schroederi Fernández-Yépez, 1958: Association of Different Classes of Repetitive DNA

Introduction: Currently, there are 38 valid species of freshwater stingrays, and these belong to the subfamily Potamotrygoninae. However, cytogenetic information about this group is limited, with studies mainly using classical techniques, Giemsa, and C-banding. Methods: In this study, we used classical and molecular cytogenetic techniques – mapping of 18S and 5S rDNA and simple sequence repeats (SSRs) – in order to investigate the karyotypic composition of Potamotrygon schroederi and reveal the karyoevolutionary trends of this group. Results: The species presented 2n = 66 chromosomes with 18m + 12sm + 16st + 20a, heterochromatic blocks distributed in the centromeric regions of all the chromosomes, and terminal blocks in the q arm of pairs 2 and 3. Mapping of 18S rDNA regions revealed multiple clusters on pairs 2 and 7 and a homolog of pair 24. The 5S rDNA region was found in the pericentromeric portion of the subtelocentric pair 16. Furthermore, dinucleotide SSRs sequences were found in the centromeric and terminal regions of different chromosomal pairs, with preferential accumulation in pair 17. In addition, we identified conspicuous blocks of (GATA)n and (GACA)n sequences colocalized with the 5S rDNA (pair 16). Conclusion: In general, this study corroborates the general trend of a reduction in 2n in the species of Potamotrygoninae subfamily. Moreover, we found that the location of rDNA regions is very similar among Potamotrygon species, and the SSRs accumulation in the second subtelocentric pair (17) seems to be a common trait in this genus.

DNA contamination and taxonomic diversity hinder eDNA research on freshwater stingray species: Comment on Lim & Then (2022)

Recently, Lim & Then (2022; Endang Species Res 48:43-50) used an environmental DNA (eDNA) PCR-based method for detecting the presence of an endangered species of freshwater stingray, Fluvitrygon kittipongi (Dasyatidae), in the Pahang River basin, east Peninsular Malaysia. For that, they designed a species-specific pair of primers to amplify a 196 base pair (bp) fragment of the cytochrome c oxidase I (COI) gene. Lim & Then (2022) reported positive detection of this species along an upstream stretch of the Pahang River during the inter-monsoon and the southwest monsoon seasons, with the PCR-amplified eDNA sequences identical to the reference COI sequences of F. kittipongi collected from the Perak River basin, west Peninsular Malaysia. Here, we argue that such positive results are likely the consequence of a DNA contamination because the 196 bp COI fragments of F. kittipongi from the Pahang River and the Perak River differ from each other by 4 nucleotide substitutions. The source of contamination in Lim & Then (2022) could have been the Perak samples the authors handled to develop the primers. We also briefly discuss the potential impact of the presumed co-occurrence of freshwater stingrays of the genus Fluvitrygon in the Pahang River on the specificity of the F. kittipongi-specific primers designed by Lim & Then (2022).

MORPHOLOGICAL CHARACTERS OF FRESHWATER STINGRAYS (CHONDRICHTHYES: DASYATIDAE) IN MUSI RIVER, PALEMBANG CITY, SOUTH SUMATERA PROVINCE

A study to determine morphological characets of freshwater stingray in Musi River of South Sumatra Province has been conducted from June to December 2020. The fishes were collected in Musi River where located at middle of Palembang city. Collected specimens were preserved to Animal Ecology Laboratory, Department of Biology, Faculty of Mathematic and Natural Science of Sriwijaya University. There are four species of freshwater stingrays collected, Fluvitrygon oxyrhyncha. Fluvitrygon kittipongi. Fluvitrygon signifer, and Fluvitrygon sp ‘musi’ 2. The results of the measurement of morphometric and morphological characteristics showed that there were differences in size and morphological characteristics of the types of fish found, indicating that stingray had different size ranges.

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

Abstract 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.

Partição de recursos entre congeners simpátricos: Um estudo de caso de raias de água doce (Potamotrygon spp.) no estuário amazônico

The syntopic occurrence of different species of freshwater stingray on a small fluvial island at the mouth of the Amazon River led to the investigation of the factors that underpin this coexistence. Stingrays were collected every two months from March 2012 to January 2013 and their exact sampling location was recorded and their stomach contents preserved and analyzed. Data were used to calculate the Levins’ index of niche breadth and Pianka’s index of niche overlap. The combined analysis of these two indices revealed four distinct scenarios, with only one of them favoring interaction between species, when feeding resources were scarce and patchily distributed. The latter conditions were found at two distinct moments during the study period – the peak of the flood and the peak of low water – whereas in other periods, the prevailing conditions were not conducive to resource sharing.

Notes on the occurrence and gender-based morphological aspects of Potamotrygon motoro (Elasmobranchii: Potamotrygonidae) in the complex of the Viana lake system- Maranhão, Brazil

The Brazilian Amazonian coast, extending from Amapá to Maranhão states, is drained by a series of small to medium sized rivers of the Amazon basin. The Pindaré-Mearim is an isolated basin formed by the junction of the Pindaré and Mearim rivers at its lower portion. Along the Pindaré and Mearim rivers there is a single reported species of freshwater stingray identified as Potamotrygon motoro. Although specimens have been deposited in research institutions, most of these specimens have been captured on the Amazon basin and its direct tributaries or along the Panará-Paraguay river basin. Hence, there is a severe lack of information on the P. motoro of the Pindaré- Mearim river basin. Here we present new data regarding P. motoro general morphology, emphasizing the color variation, sexual dimorphism and notes on its biological aspects.

Description of two extraordinary new species of freshwater stingrays ofthe genus Potamotrygon endemic to the rio Tapajós basin, Brazil(Chondrichthyes: Potamotrygonidae), with notes on other Tapajós stingrays.

Stingrays from the rio Tapajós basin are reviewed based on material collected from its lower (i.e. from the mouth-lake to Itaituba), middle (from about the São Luiz rapids to the confluence of rios Juruena and Teles Pires), and upper (above the Juruena-Teles Pires confluence) segments. Two new species endemic to the mid and upper Tapajós, discovered long ago and common in the ornamental fish trade, are described. Potamotrygon albimaculata sp. nov. is part of the black stingray species group, and is diagnosed by its blackish brown dorsal disc color with numerous and generally evenly-spaced small whitish spots and faint ocelli, multiple rows of thorns broadly spread on dorsal and lateral tail, pelvic fins with broadly rounded apices, and two angular cartilages with the posterior far more slender but about as wide as the anterior angular. Potamotrygon jabuti sp. nov. is diagnosed by its marbled color pattern that undergoes remarkable change with growth as adults have elaborate designs of beige, golden to yellowish-orange spots or ocelli surrounded by a slender beige to golden mesh-like pattern, but neonates have simple, well-separated ocelli; this species also has a single to double row of tail thorns varying in their development, monognathic heterodonty with teeth of intermediate lateral rows of upper jaws larger and hexagonal, and two robust, more or less equally developed angular cartilages. Both species co-occur in the relatively fast-flowing mid and upper Tapajós basin, but mostly occupy different areas of the river, with P. albimaculata sp. nov. more abundant in its central troughs but foraging at its margins, whereas P. jabuti sp. nov. is also present in smaller streams over rocky, sandy and leafy substrates. The Tapajós basin includes at least seven stingray species, but additional species probably also occur. Potamotrygon motoro, P. orbignyi, P. humerosa, Potamotrygon sp., and Paratrygon aiereba are present in the lower Tapajós mouth-lake, which may also include Plesiotrygon and Heliotrygon species. In addition to the new species described herein, P. orbignyi and Paratrygon cf. aiereba occur in the mid and upper Tapajós, along with another form (Potamotrygon cf. scobina) known only from the region of the São Luiz rapids. Therefore, three additional new species may be present in the Tapajós basin, which has one of the most diverse stingray assemblages known together with the rios Negro and Tocantins-Araguaia.

Relação entre as Populações Naturais de Arraias de Água Doce (Myliobatiformes: Potamotrygonidae) e Pescadores no Baixo Rio Juruá, Estado do Amazonas, Brasil

The aim of this study was characterize the stingrays negative fishing freshwater in the municipality of Jurua, Amazonas. They were interviewed 50 registered fishermen in Cologne Jurua Fishermen, Z21. The potamotrigonids were mainly caught with gillnets. Occur nine species of freshwater stingrays in Jurua, the most abundant Potamotrygon motoro and Potamotrygon cf. scobina. Freshwater stingrays have been found in lakes, rivers and beaches, with the highest occurrence period in seasons of low water and dry of Jurua River. The destination given to stingrays by fishermen after their fishing was death the animals (59%), mutilation (35%) and release in wild areas (6%). It was estimated that in 2012 there was the sacrifice of 10,660, mutilation of 3562 and the release of only 286 stingrays. Half part of the respondents suffered injury, with attacks mainly in the feet (70%).There is a high diversity of potamotrigonids the Jurua River. Is important to adopt environmental education measures with the fishermen to prevent overfishing and thus keep such elasmobranchs in the locality. Keywords: Potamotrygonidae; mortality; diversity; negative.

Hematology, biochemical profile and thyroid hormones of four species of freshwater stingrays of the genus Potamotrygon

<p>Potamotrygonidae e um grupo de raias endêmicas da América do Sul distribuídas nas principais bacias hidrográficas brasileiras, mas informações sobre suas variáveis hematológicas e bioquímicas são escassas. Este estudo teve como objetivo determinar estas variáveis em <em>Potamotrygon motoro </em>e <em>P. falkneri </em>na Bacia do Rio Paraná, Estado do Paraná e de <em>P. orbignyi </em>e <em>P. scobina </em>do Rio Piririm, na Bacia Amazônica, Estado do Amapá. Foi capturado um total de 53 espécimes de <em>Potamotrygon </em>spp. para colheita de sangue e avaliações do hemograma e variáveis bioquímicas séricas. Os valores do hemograma foram próximos para as quatro espécies e os resultados com diferenças significativas entre <em>Potamotrygon falkneri</em>, <em>P. motoro, P. orbigni </em>e <em>P. scobina </em>ocorreram quanto ao número de eritrócitos e heterófilos. Apesar da diversidade geográfica os resultados apresentaram pouca interferência dos diferentes habitats nas variáveis avaliadas. Os níveis de proteínas, globulinas, relação albumina:globulina, acido úrico, creatinina, ureia, HDL-C, relação cálcio:fósforo, sódio, cloreto, AST, ALT, creatinoquinase (CK), fosfatase alcalina, hormônios triiodotironina (T3) e tiroxina (T4) não diferiram entre as espécies de Potamotrygon. Porem, os níveis de albumina, glicose, colesterol total, triglicerídeos e gama glutamil transferase (GGT) apresentaram diferenças. Este fato sugere pouca interferência do habitat nas variáveis avaliadas apesar da diversidade geográfica de origem das raias de vida livre.</p>

A New Genus and Species of Freshwater Stingray (Myliobatiformes, Dasyatoidea) from the Latest Middle Eocene of Utah, U.S.A.

Teeth of a new freshwater dasyatoid ray recovered from the latest middle Eocene Brian Head Formation of southern Utah represent the youngest freshwater stingray so far known in the fossil record of North America. The crown morphology of Saltirius utahensis n. gen. n. sp. exhibits strong sexual dimorphism, with the presumed males bearing two prominent margino-labial protuberances and a bifid cusp that produces a saltire-like outline. This unique crown separates this genus and species from any known extinct or extant myliobatiform, but does have some resemblance to the crown of Asterotrygon maloneyi from the lower Eocene Green River Formation of Wyoming. The occurrence of S. utahensis in the Brian Head Formation provides additional evidence for the persistence of warm subtropical temperatures during the late Eocene in southern Utah.

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

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.

An unusual, dwarf new species of Neotropical freshwater stingray, Plesiotrygon nana sp. nov., from the upper and mid Amazon basin: the second species of Plesiotrygon (Chondrichthyes: Potamotrygonidae)

A new species of the relatively poorly known Neotropical freshwater stingray genus Plesiotrygon Rosa, Castello & Thorson, 1987 is described from the main channel and smaller tributaries (Ríos Itaya and Pachitea) of the upper Amazon basin in Peru. The first specimen to be collected, however, was from much farther east in Rio Solimões in 1996, just down-river from Rio Purus (specimen unavailable for this study). Plesiotrygon nana sp. nov., is a very distinctive and unusually small species of freshwater stingray (Potamotrygonidae), described here mostly from three specimens representing different size classes and stages of sexual maturity. Plesiotrygon nana sp. nov., is distinguished from its only congener, P. iwamae Rosa, Castello & Thorson, 1987, by numerous unique features, including: dorsal coloration composed of very fine rosettes or a combination of spots and irregular ocelli; very circular disc and snout; very small and less rhomboidal spiracles; short snout and anterior disc region; narrow mouth and nostrils; denticles on dorsal tail small, scattered, not forming row of enlarged spines; adult and preadult specimens with significantly fewer tooth rows; fewer caudal vertebrae; higher total pectoral radials; very small size, probably not surpassing 250 mm disc length or width, males maturing sexually at around 180 mm disc length and 175 mm disc width; distal coloration of tail posterior to caudal stings usually dark purplish-brown; and features of the ventral lateral-line canals (hyomandibular canal very narrow, infraorbital and supraorbital canals not undulated, supraorbital and infraorbital loops small and narrow, supraorbital loop very short, not extending posteriorly to level of mouth, jugular and posterior infraorbital canals short, not extending caudally to first gill slits, subpleural loop very narrow posteriorly; absence of anterior and posterior subpleural tubules). To provide a foundation for the description of P. nana sp. nov., morphological variation in P. iwamae was examined based on all type specimens as well as newly collected and previously unreported material. Two specimens topotypic with the male paratype of P. nana sp. nov., referred to here as Plesiotrygon cf. iwamae, are also reported. Relationships of the new species to P. iwamae are discussed; further characters indicative of Plesiotrygon monophyly are proposed, but the genus may still not be valid. Plesiotrygon nana sp. nov., is commercialized with some regularity in the international aquarium trade from Iquitos (Peru), an alarming circumstance because nothing is known of its biology or conservation requirements.

Phylogeny and taxonomy of Potamotrygonocotyle Mayes, Brooks & Thorson, 1981 (Monogenoidea: Monocotylidae) with a description of four new species

The marine-derived stingrays of Potamotrygonidae, endemic to South American river systems, host an interesting parasite fauna equally related to marine lineages. Among those lineages, the diversity and phylogenetic relationships within Potamotrygonocotyle - a monocotylid monogenoidean specific to potamotrygonids - are poorly known, since 9 of 10 species attributed to this genus have been described in the past 3 years. Here, we readdress the diversity of Potamotrygonocotyle after examining the gills of 436 potamotrygonid individuals representing 12 described and 14 potentially undescribed species of freshwater stingrays from 19 major river systems of South America (i.e. sub-basins). We recognized 12 valid species within the parasite genus, of which four are described in this study. Our taxonomic decisions were based on the phylogenetic analysis of 14 ingroup terminal taxa and 12 morphological characters, which resulted in the following hypothesis of sister-group relationships: ((P. dromedarius, P. tatianae sp. nov.), (P. rionegrense, P. auriculocotyle sp. nov., ((P. quadracotyle, P. umbella), (P. septemcotyle sp. nov., (P. chisholmae, P. uruguayense)), (P. tsalickisi, P. eurypotamoxenus, P. rarum, (P. tocantinsense sp. nov., P. aramasae))))). According to our hypothesis, the absence of autapomorphic features for some nominal species, and the re-evaluation of morphological variation among populations, led us to consider P. eurypotamoxenus and P. uruguayense as junior synonymys of P. tsalicksi and P. chisholmae, respectively. Finally, we address the importance of biogeographic and host representation, in order to fully understand the patterns of morphological variation and host specificity within this group. We found that hypotheses of species delimitation depend greatly on efforts to sample specimens throughout its distributional range and that host specificity within this genus varies dramatically among lineages.