On the occurrence of the tropical caprellid Paracaprella pusilla Mayer, 1890 (Crustacea: Amphipoda) in Europe

Paracaprella pusilla Mayer, 1980 is a tropical caprellid amphipod species. It was first described from Brazil and is found to be very common along the Atlantic coast of Central America. Since its original description, P. pusilla has been found in prolific volumes at numerous widespread locations in tropical and subtropical seas around the world, and is primarily associated with fouling communities in harbors. A well established population of P. pusilla was recently found in Cádiz, southern Spain, which is both the northernmost collection and the first recorded finding of this species in European coastal waters. Ship fouling is the most probable vector for its introduction. The species was always found in association with the native hydroid Eudendrium racemosum (Cavolini, 1785) and appeared to display a mutualistic relationship with this hos