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Taxonomic and morphological revision of the genus Paratrygon Duméril (1865) (Chondrichthyes: Myliobatiformes: Potamotrygonidae)

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Thiago Silva Loboda
Total Authors: 1
Document type: Doctoral Thesis
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
Defense date:
Examining board members:
Marcelo Rodrigues de Carvalho; Marcelo Roberto Souto de Melo; Alessio Datovo da Silva; João Paulo Capretz Batista da Silva; Luis Fábio Silveira
Advisor: Marcelo Rodrigues de Carvalho

The genus Paratrygon Duméril (1865) so far recognized as the unique monotypic genus of the family Potamotrygonidae, shows a considerable high diversity previously indicated by molecular studies which pointed P. aiereba (its unique species) as a possible species complex. Eight new specific groups were recognized here through morphological and morphometric data: P. sp.1 and P. sp.2 endemic and sympatric to Orinoco basin, P. sp.3 endemic to Rio Branco, P. sp.4 endemic to Rio Negro, P. sp.5 endemic to Rio Tapajós, P. sp.6, endemic to Rio Araguaia, P. sp.7, endemic to Rio Tocantins, and P. sp.8 endemic to Rio Xingu. Distribuiton of P. aiereba is restricted to Amazon basin. All specific groups were identified and defined through caracters such as coloration, dermal denticles morphology, pointed caudal spines, distribution of ventral canals of lateral line, morphology of skeletal elements and morphometrics. Nominal species Disceus thayeri Garman (1913) was confirmed as junior synonymous of P. aiereba by analyzes of its type-specimens (MCZ 297-S, 563-S, 606-S). Nominal species Trygon strogylopterus Schomburgk (1843) was correlated to one of the specific groups, P. sp.3, by morphological analyzes of its type-specimen ZMB 4632 and therefore will soon be resurrected. Lastly, the clades Paratrygon + Heliotrygon and Potamotrygon + Plesiotrygon are also corroborated by morphological and morphometric data, and the taxonomic recognition of these groups inside the family Potamotrygonidae it turns out necessary to better understanding the evolution of neotropical freshwater stingrays (AU)