A new caprellid species (Crustacea: Amphipoda: Senticaudata) from Brazil.

A new species of caprellid, Pseudaeginella arraialensis, is described from Arraial do Cabo, Rio de Janeiro, Brazil. Abundant material was collected in Praia do Forno, associated to hydroids and algae of natural rocky substrata and fouling communities of artificial floating structures. The new species can be distinguished easily from the remaining species in the genus mainly by the pattern of dorsal projections, and by the setose antennae and gnathopod 2 in males. The dietary analysis revealed that the species is omnivorous, with a high contribution of small crustaceans in its diet. Detailed figures showing ontogenetic development and intraspecific variation of P. arraialensis are also included.

A new species of Paracaprella Mayer, 1890 (Amphipoda: Caprellida: Caprellidae) from southern Brazil.

A new species of the genus Paracaprella is described based on the specimens associated with the algae Sargassum cymosum and Laurencia obtusa that were collected from infralittoral depths (0.5 to 3.0 m) at Sepultura Beach, Bombinhas and Paciência Beach, Penha, Santa Catarina State, Brazil. This new species differs from the others of the genus by the unique morphology of the males' gnathopod 2: its propodus has a grasping margin provided with a deep groove. An identification key for Paracaprella species is also presented.

The Panama Canal and the transoceanic dispersal of marine invertebrates: evaluation of the introduced amphipod Paracaprella pusilla Mayer, 1890 in the Pacific Ocean.

Although the Panama Canal is one of the major corridors for shipping and potential dispersal of marine invaders in the tropics, little is known about the effect that the Canal has had on the distribution of marine biota. In this study, we (a) document the existence of established populations of the Western Atlantic caprellid amphipod Paracaprella pusilla, Mayer, 1890 for the first time at the Pacific entrance to the Canal, (b) review its distribution in the Pacific Ocean, and (c) evaluate possible mechanisms of introduction. The confirmed distribution of P. pusilla in the Pacific Ocean is limited to Australia, Hawaii, and Panama, despite earlier published reports from Chile and China. Laboratory experiments demonstrated intolerance of P. pusilla to freshwater, causing 100% mortality, and suggest invasion of the Pacific coast of Panama occurred through the Canal via ships' ballast water or by secondary spread via ships (ballast water or hull fouling) from another Pacific region.