Ergasilus urupaensis sp. n. (Copepoda, Poecilostomatoida, Ergasilidae) is proposed. The specimens were collected from the gill filaments of the freshwater fishes Prochilodus nigricans, from Urupá River, Rondônia state, Brazil. The new species has a curved pectinate seta on the first exopod that indicates relationship to five previously described Amazonian species. This species differs from others in the shape of cephalosome, ornamentation of the legs and antenna and by having a larger body.
Copepoda; Ergasilus urupaensis; Poecilostomatoida; Ergasilidae; Amazon