Description of a novel genus with three new species of Phoxocephalidae G. O. Sars, 1891 (Crustacea: Amphipoda) from off northeastern Brazil.

Magnaphoxus ajaja gen. et sp. nov., Ma. simplex gen. et sp. nov. and Ma. longicarpus gen. et sp. nov. are described. The material examined was collected off the states of Cear, Rio Grande do Norte and Bahia during the projects Avaliao da Biota Bentnica e Planctnica na poro offshore das Bacias Potiguar e Cear (BPOT) and Programa de Avaliao do Potencial Sustentvel de Recursos Vivos na Zona Econmica Exclusiva (REVIZEE). Additionally, material from other surveys off Brazilian northeastern coast is included. The samples were collected by rectangular dredges, box corer and Van Veen grabs, ranging from shallow waters to 168 meters in depth. The new genus is morphologically similar to the genera Grandifoxus Barnard, 1979, Metharpinia Schellenberg, 1931, Microphoxus Barnard, 1960 and Rhepoxynius Barnard, 1979. However, it can be recognized by the exclusive constricted and very broad rostrum and bilobated coxa 6, plus the combination of characters such as: lower lip outer plate with apical cusps; right mandible without lacinia mobilis; pereopods 34 carpus posterior margin with one distal robust long seta; propodus strongly armed with robust setae; uropods 12 peduncle dorsolateral margin combed distally; telson with two apical robust setae on each side. All three new species, are fully described, illustrated, and discussed.