A new species of Elasmopus Costa (Amphipoda: Maeridae) from the coast of Rio de Janeiro state, southeastern Brazil

Abstract

A new species of Elasmopus Costa, 1853 is described. The material examined was collected by SCUBA diving at the Itaipu and Boa Viagem beaches, municipality of Niterói, Rio de Janeiro state, Brazil. Elasmopus helenae sp.n. belongs to the castelloserrate group within the genus and is diagnosed by: antenna I accessory flagellum 2-or 3-articulated; gnathopod II with propodus subovoid and tapering distally, palm presenting two processes, medial one almost subquadrate, subdistal subtriangular but apically rounded; basis of pereopod V with posterior margin weakly serrate; basis of pereopods VI and VII with distal half of posterior margin castelloserrate; uropod I peduncle with two stout basofacial setae; and telson deeply cleft, each lobe apically truncate with an apicolateral and an apicomesial cusp.