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Preliminary data on the feeding habits of the freshwater stingrays Potamotrygon falkneri and Potamotrygon motoro (Potamotrygonidae) from the Upper Paraná River basin, Brazil
Silva, Thiago Buosi;Uieda, Virgínia Sanches;
Biota Neotropica , 2007, DOI: 10.1590/S1676-06032007000100027
Abstract: stingrays of the potamotrygonidae family are a singular group of neotropical ichthyofauna. although ancient reports exist about the group, there are still many questions that need to be clarified, such as the biology of the species that occur in the paraná-paraguay river system. in the present work, the diet of potamotrygon falkneri and potamotrygon motoro, captured in the upper paraná river, downstream from the engenheiro souza dias hydroelectric power station (uhe jupiá), was analyzed. both species showed a diversified diet, consisting of 14 food items, including mollusca, crustacea, insecta and fish, with the predominance in diversity and abundance of aquatic insects. only one individual of each species ingested fish. potamotrygon motoro consumed mainly ephemeroptera, while p. falkneri consumed mainly mollusca, hemiptera and trichoptera. the data apparently indicate a more specialized diet for p. motoro, consuming more ephemeroptera (baetidae), and a more generalized diet for p. falkneri. the analysis of individuals captured in three microhabitats that differ in function of the substrate type and presence of marginal vegetation, suggests differences in the food items consumed.
A taxonomic and morphological redescription of Potamotrygon falkneri Castex & Maciel, 1963 (Chondrichthyes: Myliobatiformes: Potamotrygonidae)
Silva, Jo?o Paulo C. B. da;Carvalho, Marcelo R. de;
Neotropical Ichthyology , 2011, DOI: 10.1590/S1679-62252011000100021
Abstract: 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.
Feeding behavior of the Neotropical freshwater stingray Potamotrygon motoro (Elasmobranchii: Potamotrygonidae)
Shibuya, Akemi;Zuanon, Jansen;Tanaka, Sho;
Neotropical Ichthyology , 2012, DOI: 10.1590/S1679-62252012000100018
Abstract: the feeding mechanisms of elasmobranchs and their functioning have been receiving growing scientific attention, although less emphasis has yet to be directed towards batoid species. the present study investigated the use of orobranchial musculature during prey capture and processing behavior in potamotrygon motoro. ten orobranchial muscle groups were removed to determine their relative biomasses. the kinematics of the musculature was described based on videos of prey capture and manipulation under captive conditions recorded at 250 and 500 field/s. analyses of the orobranchial musculature indicated that adductor muscles responsible for closing the mouth had high biomasses, which is consistent with their functions related to apprehend and manipulate the prey. the feeding behavior adopted by this ray species showed a sequence of manipulation to crush hard prey as crustaceans (dominant prey category for p. motoro) to facilitate final oral transport. the morphological and behavioral characteristics of p. motoro are essential to fully understanding the mechanisms used in prey capture and processing in environments in which these stingrays occur.
A test of the utility of DNA barcoding in the radiation of the freshwater stingray genus Potamotrygon (Potamotrygonidae, Myliobatiformes)
Toffoli, Daniel;Hrbek, Tomas;Araújo, Maria Lúcia Góes de;Almeida, Maurício Pinto de;Charvet-Almeida, Patricia;Farias, Izeni Pires;
Genetics and Molecular Biology , 2008, DOI: 10.1590/S1415-47572008000200028
Abstract: 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.
Morfometria de raias continentais (Chondrichthyes, Potamotrygonidae) do alto rio Paraná, Brasil = Morphometry of upper Paraná river freshwater stingrays (Chondrichthyes, Potamotrygonidae)  [cached]
Antonio Guilherme Candido da Silva,Erivelto Goulart
Acta Scientiarum : Biological Sciences , 2007,
Abstract: Potamotrygonidae constitui o único grupo recente de Chondrichthyes cujo habitat está restrito, exclusivamente, a águas continentais. Na planície de inunda o do Alto rio Paraná, espécies desta família estabeleceram-se após o fechamento das comportas da usina hidrelétrica de Itaipu, a jusante. O objetivo deste trabalho foi, utilizando medidas corporais, identificar diferen as morfométricas entre indivíduos de Potamotrygon cf. motoro (Natterer in Müller & Henle, 1841) e Potamotrygon falkneri Castex & Maciel, 1963 capturadosnesta regi o, bem como estimar o tamanho com que machos destas espécies atingem a maturidade gonadal. Machos de P. falkneri e P. cf. motoro das popula es avaliadas atingem a maturidade gonadal com largura do disco variando em torno de 26 cm e 23 cm, respectivamente. Na compara o das espécies, P. cf. motoro apresentou maior distanciaproporcional entre as narinas e maior comprimento proporcional da cauda e dos espiráculos. Identificou-se dimorfismo sexual secundário para P. falkneri, consistindo da presen a de fileiras laterais de espinhos na cauda das fêmeas. Estudos futuros de morfologiafuncional e ecomorfologia poder o esclarecer o significado das diferen as morfométricas para o modo de vida destas espécies. Potamotrygonidae is the only extant chondrichthyan group restricted exclusively to freshwater. This family invaded the UpperParaná river system after the closing of Itaipu Dam. This study aimed to identify morphometric differences between Potamotrygon cf. motoro (Natterer in Müller & Henle, 1841) and Potamotrygon falkneri Castex & Maciel, 1963 sampled in that area, and estimate male size at gonadal maturation. P. falkneri and P. cf. motoro males reach gonadal maturation at 26 cm and 23 cm disc width, respectively. Comparing both species, P. cf. motoro presented larger tail, spiracles and distance between nostrils. Lateral small stings on tails ofP. falkneri females were observed as secondary sexual dimorphism. Further studies on functional morphology and ecomorphology may point the meaning of morphometric differences to these species’ ecological interactions.
Hábitos alimentares e sobreposi o trófica das raias Potamotrygon falkneri e Potamotrygon motoro (Chondrichthyes, Potamotrygonidae) na planície alagável do alto rio Paraná, Brasil = Feeding habitats and trophic overlap of the freshwater stingrays Potamotrygon falkneri e Potamotrygon motoro (Chondrichthyes, Potamotrygonidae) in the upper Paraná river floodplain, Brazil  [cached]
Alessandra Pasian Lonardoni,Erivelto Goulart,Edson Fontes de Oliveira,Milza Celi Fedatto Abelha
Acta Scientiarum : Biological Sciences , 2006,
Abstract: As raias Potamotrygon falkneri e Potamotrygon motoro foram avaliadas em rela o à composi o de suas dietas e a sobreposi o do nicho trófico nos períodos de seca (agosto/2004) e cheia (janeiro/2005) na planície alagável do alto rio Paraná, em três esta es de coleta próximas à ilha Mutum. Foram analisados 49 conteúdos estomacais de P. falkneri e 16 de P. motoro, obtidos de espécimes capturados através de pesca com anzol, fisga (arp o) e espinhel. Os conteúdos estomacais foram analisados de acordo com os métodos de freqüência volumétrica e de ocorrência. A similaridade da dieta foi quantificada pelo índicede sobreposi o de Pianka. As espécies revelaram flexibilidade alimentar, com ambas consumindo predominantemente moluscos na cheia, enquanto na seca a dieta de P. falkneri foi composta principalmente por peixes e a de P. motoro por insetos aquáticos. Os valores doíndice de sobreposi o de nicho variaram entre 0,38 na seca (moderado) e 0,94 na cheia (acentuado). A varia o da composi o das dietas foi atribuída às oscila es na disponibilidade dos recursos alimentares no ambiente. Feeding habits and trophic overlap of freshwater stingrays Potamotrygon falkneri e Potamotrygon motoro were evaluated in the upper Paraná river floodplain. Samples were collected during periods of drought (August/2004) and flood (January/2005) near Mutum island. Fishhook, harpoon and long line were used to capture the individuals and a total of 49 stomach contents of P. falkneri and 16 of P. motorowere analyzed. Diet composition was analyzed by the relative occurrence and volumetric frequencies. The trophic overlap was quantified by the index of niche overlap of Pianka. Results indicated that both species predominantly consumed mollusks during the floodseason, while in the drought season the diet of P. falkneri was composed mainly by fish and P. motoro for aquatic insects. The values of the index of niche overlap varied from 0.38, in drought (moderate), to 0.94 in flood (accentuated). The seasonal variation of the composition of the diets was attributed to fluctuations in the availability of food resources in the floodplain.
Potamotrygon boesemani (Chondrichthyes: Myliobatiformes: Potamotrygonidae), a new species of Neotropical freshwater stingray from Surinam
Rosa, Ricardo S.;Carvalho, Marcelo R. de;Wanderley, Cristiane de Almeida;
Neotropical Ichthyology , 2008, DOI: 10.1590/S1679-62252008000100001
Abstract: potamotrygon boesemani, new species, is described from the corantijn river drainage in surinam. the species has a diagnostic dorsal color pattern formed by deep orange to red ocellated spots of irregular form, encircled by relatively broad black rings. potamotrygon boesemani is distinguished from other ocellated congeners (p. motoro, p. henlei and p. leopoldi) by the more intensely colored ocelli, which are usually yellow in the latter species. from p. motoro it is also distinguished by the darker dorsal background coloration, by the broader black contour of the dorsal ocelli, and by the irregular form of the ocelli as compared to the more rounded shape in the latter species. from p. henlei and p. leopoldi, it is distinguished by the lack of ocelli on tail. from the tentatively identified specimen of p. ocellata, which also has dark orange ocelli, the irregular contour of the ocelli in the new species is also distinctive. the teeth are relatively smaller and in greater number than in p. motoro and p. ocellata, with up to 45 rows in the upper jaw.
Diet of the freshwater stingray Potamotrygon motoro (Chondrichthyes: Potamotrygonidae) on Marajó Island (Pará, Brazil)
Almeida, MP.;Lins, PMO.;Charvet-Almeida, P.;Barthem, RB.;
Brazilian Journal of Biology , 2010, DOI: 10.1590/S1519-69842010000100022
Abstract: the stomach contents of 137 examples of potamotrygon motoro caught in 3 locations (muaná, afuá and lake arari) on marajó island were analysed. the values of the index of relative importance (iri) and its respective percentage (%iri) were calculated. the level of repletion 1 (? full) was the most representative for both sexes, as well as for immature and mature specimens. most of the food items found were well-digested. the food items identification indicated the presence of 15 orders, including insects, mollusks, crustaceans, annelids and fish. differences in diet were observed among the locations studied when comparing %iri, crustaceans being the most preferred in afuá, fish in lake arari and mollusks in muaná.
A new species of Neotropical freshwater stingray of the genus Potamotrygon Garman, 1877 from the Río Madrede Díos, Peru (Chondrichthyes: Potamotrygonidae)
Silva, Jo?o Paulo C.B. da;Carvalho, Marcelo R. de;
Papéis Avulsos de Zoologia (S?o Paulo) , 2011, DOI: 10.1590/S0031-10492011000800001
Abstract: potamotrygon tatianae sp. nov., is described from río madre de díos, peru, upper rio madeira basin. the new species is distinguished from all congeners by a unique combination of characters, including its dorsal color pattern formed by a relatively slender, highly convoluted, beige to dark brown vermicular pattern, a single row of dorsal tail spines, and a relatively longer tail posterior to caudal stings. potamotrygon tatianae sp. nov., occurs sympatrically with other species of potamotrygon (p. falkneri, p. orbignyi and p. motoro). from the similar species p. falkneri, p. tatianae sp. nov., is further distinguished by the absence of circular, reniform, and oval spots, by its proportionally much longer tail, by having dorsal tail spines in one irregular row, and by features of the ventral lateral-line canal, dermal denticles and neurocranium. from p. orbignyi, the new species is distinct by lacking a reticulate pattern on dorsal disc and by the presence of two angular cartilages. from p. motoro, p. tatianae sp. nov., is further separated by the lack of ocelli formed by strong black concentric rings, by the more flattened aspect of its head and disc, and by having smaller and more numerous teeth. the discovery of a new species that so closely resembles a congeneric form in color pattern, a feature highly variable within the latter, highlights the importance of examining large series of individuals and of detailed morphological analyses in revealing the potentially highly cryptic nature of the diversity within the family.
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
Cruz, Vanessa Paes da;Shimabukuro-Dias, Cristiane Kioko;Oliveira, Claudio;Foresti, Fausto;
Neotropical Ichthyology , 2011, DOI: 10.1590/S1679-62252011000100020
Abstract: cytogenetic analysis of potamotrygon aff. motoro and p. falkneri indicated the occurrence of an x1x1x2x2/x1x2 y 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.
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