A new species of Diaphorocleidus (Monogenea: Ancyrocephalinae) from the gills of Argonectes robertsi (Characiformes) and new records of dactylogyrids parasitic on fishes from the Xingu River, Amazon Basin, Brazil

Diaphorocleidus altamirensis sp. nov., parasitic on the gills of Argonectes robertsi Langeani, 1999 from the Xingu River, northern Brazil, is described. The new species differs from its six congeners by the morphology of the male copulatory organ (which comprises a coil of six rings), by the midventral vagina, and by the presence of only one pair of eyespots. It is the first species of Diaphorocleidus Jogunoori, Kritsky & Venkatanarasaiah, 2004 described from hemiodontid fishes. In addition, new host and geographical records of seven species of dactylogyrids found on fish from the Xingu River are reported.