Species of the eutetrarhynchid genus Hispidorhynchus Schaeffner and Beveridge, 2012 possess an uncinate macrohook on the bothrial surface of the basal swelling of each tentacle. This unique feature of the oncotaxy is only shared with the closely related genus Oncomegas Dollfus, 1929. A new species of Hispidorhynchus is described from specimens infecting Styracura schmardae (Werner, 1904) (Potamotrygonidae) from the western Caribbean Sea off the coast of Belize and Panama. Hispidorhynchus styracurae n. sp. differs from its 3 congeners in the possession of smaller and narrower bulbs, fewer principle hooks in the metabasal armature, size of the macrohook, and different scolex proportions. Scanning electron microscopy reveals new information on the microthrix morphology of the genus. A diagnostic key for the differentiation of species of Hispidorhynchus is provided. In addition, new host and locality records are reported for Oncomegas wageneri (Linton, 1890) Dollfus, 1929, collected from Hypanus guttatus (Bloch and Schneider, 1801) (Dasyatidae) off the coast of Maceió, Alagoas (Brazil). This considerably expands the geographical distribution of this species in the western Atlantic Ocean.