A new species of copepod is described from brown trout (Salmotrutta) and reported from salmon (Oncorhynchus tschawytscha) in New Zealand freshwater; from information gained from an examination of the type of Paeonodes exiguus the new species is placed in this genus, and the genus transferred to the family Therodamasidae. Since most, if not all, New Zealand salmonids were introduced as fertilized ova, the new parasite may later be found on endemic fish species.