Ergasilus trygonophilus sp. nov. (Copepoda: Ergasilidae) a branchial parasite of freshwater stingrays (Potamotrygonidae) from state of Pará, Brazil

Ergasilus trygonophilus sp. nov. is described from freshwater stingrays (Potamotrygon spp. and Plesiotrygon iwamae Rosa, Castello & Thorson, 1987) from the state of Pará, Brazil. The new species differs from all known species of Ergasilus Nordman, 1832 from Brazilian waters by possessing: (1) an elongate bullet-shaped cephalosome; (2) antennule setal formula 1: 10: 4: 4: 2 + 1 ae: 6 + 1 ae; (3) maxillule bearing two distal setae; and (4) terminal endopodal segment of leg 1 with rosette-like array of blunt spinules. This is the first species of a freshwater stingray Ergasilus reported from Brazil