<p>A new species of <i>Eudactylina</i> (Siphonostomatoida: Eudactylinidae) was found parasitizing the gills of the longnose stingray <i>Hypanus guttatus</i> (Bloch &amp; Schneider) from the Brazilian Amazon coast. Fieldwork was conducted at the Municipality of Raposa, State of Maranhão, Brazil, where specimens of <i>H. guttatus</i> were acquired from local fishermen. Copepods were recovered from the gill lamellae and fixed in 80% ethanol for morphological analysis. Detailed examination was performed using light and scanning electron microscopy. <i>Eudactylina amazonica</i> sp. nov. can be distinguished from its congeners by a unique combination of morphological features including intersomitic ornamentation, morphology of the rostrum and segmentation and armature of legs. The present study represents the first record of an eudactylinid copepod along the Brazilian coastline, and a novel report of <i>H. guttatus</i> as host of these parasites. In addition, a list of parasitic copepods on elasmobranchs in Brazil is presented, which documents how poorly sampled and understudied these highly diverse organisms are in the country. These results provide new data to the baseline knowledge of parasite biodiversity in a sensitive and biodiverse region, and highlight the need for further parasitological surveys on elasmobranchs in South America.</p>