Elasmopus, Costa, 1853

Pereira, C. S. M., Andrade, L. F. & Senna, A. R., 2022, A new species of Elasmopus Costa (Amphipoda: Maeridae) from the coast of Rio de Janeiro state, southeastern Brazil, Invertebrate Zoology 19 (1), pp. 42-56 : 44

Genus Elasmopus Costa, 1853

TYPE SPECIES. Elasmopus rapax Costa, 1853 .

DIAGNOSIS. Lateral cephalic lobe short, anteroventral cephalic notch present. Antenna 1 longer than antenna 2, accessory flagellum with at least 2 articles. Lower lip with present inner lobes. Mandible palp segment 3 falciform. Maxilla 1 inner plate suboval to subrectangular, inner margin not or weakly setose, apical margin with 1–2 plumose setae; outer plate with multi-cuspidate setae apically. Maxilla 2 inner plate without facial setal row. Gnathopods 1–2 subchelate, different in shape and size (male gnathopod 1 much smaller than gnathopod 2), palms acute to extremely acute. Coxae slightly elongate; coxa 4 with rounded to subquadrate posterodistal lobe. Pereopods 5–7 usually short and stout, basis with posteroventral lobe. Uropod 1 peduncle with none to two basofacial setae; rami subequal in size. Uropod 3 rami short, apically truncate, outer ramus broad and strongly setose, 1-articulate or with vestigial article 2. Telson usually deeply cleft (after Senna, Souza-Filho, 2011).