Systematics and phylogeny of Potamotrygonocestus (Platyhelminthes, Tetraphyllidea, Onchobothriidae) with descriptions of three new species from freshwater potamotrygonids (Myliobatoidei, Potamotrygonidae) - Marques, Fernando; Brooks, Daniel R; Araújo, Maria L. G. (Zoologica Scripta, 2003)