EN
A new species of Ergasilus von Nordmann, 1832 (Copepoda, Ergasilidae) parasitic on the gills of sea catfish, Aspistor luniscutis (Valenciennes, 1840) (Ariidae) from the coastal zone of the state of Rio de Janeiro, Brazil is described and illustrated. The new species is characterized by the presence of 2-segmented first endopod with rosette-like array of blunt spinules, 3-seg- mented fourth endopod, first antennulary segment with single seta and not inflated cephalosome.