Aeginina longicornis (Amphipoda: Caprellidea), new intermediate host for Echinorhynchus gadi (Acanthocephala: Echinorhynchidae).

Cystacanths of the acanthocephalan Echinorhynchus gadi were found infecting the caprellid amphipod Aeginina longicornis on Banquereau, an offshore bank on the Scotian Shelf east of Nova Scotia, Canada. Two of 229 amphipods (0.9%) were each infected with a single male cystacanth. This is the first report of an intermediate host for E. gadi in the western Atlantic Ocean and the first record of A. longicornis as an intermediate host for any helminth. The cystacanths are described.