Revisão filogenética da família Potamotrygonidae (Elasmobranchii - Myliobatifome)

Abstract

The Potamotrygonidae, popularly known as fresh-water sting rays, is exclusive from South America. Its origin is probably marine and the group had colonized the inland waters from an epicontinental sea that existed during the Early Miocene (about 20 million years). Potamotrygonids can be found on the principal South American basins as Amazon, Plata, and Orinoco drainages. Potamotrygonidae is composed by about 20 nominal species, divided in four genera that have synapomorphies that support the validity of the family. The aim of this study is to present a phylogenetic analysis of Potamotrigonidae, based on morphological characters. The preparation of the specimens, for a better observation of morphological characters, was made usind manual dissection of fresh specimens; dry-skeletons and mammographies were also used in this study. The phylogenetic analysis was obtained using PAUP (Phylogenetic Analysis Using Parsimony) software, version 4.0. The phylogenetic analysis based on morphological information shows that within the Potamotrynonidae, five characters support the clade consisting by Paratrygon aiereba and Heliotrygon gomesi. The species Potamotrygon schumacheri, P. castexi e Plesiotrygon iwamae conform a clade supported by seven characters. Potamotrygon castexi e Plesiotrygon iwamae form a clade supporting by two characters. Paratrygon and Heliotrygon are hypothesized as a monophyletic group. The species Plesiotrygon iwamae is positioned within the genus Potamotrygon, thereby showing the paraphyletic status of the Potamotrygon.Our results demonstrate the necessity of an exhausted phylogenetic study of Potamotrygonidae increasing valid characters