Monocorophium acherusicum (Costa, 1851)

Monocorophium acherusicum (Costa, 1851) View in CoL

Figure 5 View FIGURE 5

Material Examined: 1 male 3.5 mm, 23º53’ S e 46º 11’ W, intertidal, col. Umbuzeiro, G., 28/11/2008, MZUSP 19617.

Diagnosis: Rostrum of male minute, deeply recessed to lateral head lobes. Male antenna 1 peduncular article 1 with 1 distal robust seta on ventromedial margin. Female antenna 1 peduncular aticle 1 with 3–4 robust setae on dorsomedial margin and 4–5 robust setae on ventral margin. Male antenna 2 strongly pediform; peduncle article 4 with 1 long and 2 short acute process on vetrodistal corner, peduncle article 5 with distal process on ventral margin; flagellum short weakly setose. Female antenna 2 articles 3–5 with robust setae on ventromedial margin. Male gnathopod 2 dactylus with 2 teeth on flexor margin, unequal in length. Male pereopod 7 basis medium broad. Urosome segments fused. Uropod 1, peduncle with 2–4 robust setae on medial margin; uropod 2 rami with robust setae on apical margins; uropod 3 ramus rounded apically.

Remarks: Monocorophium acherusicum has cosmopolitan distribution and it is perhaps the most widely distributed species of corophiin amphipod in temperate-tropical waters of the world ( Bousfield & Hoover, 1997). This species was recorded form Brazilian waters for Serejo, 1998, that appointed some variations on numbers of robust setae of antennae peduncle, comparing the Brazilian specimens with descriptions of Chevreux & Fage, 1925; Bousfield, 1973 and Myers, 1982. But this species is distinguished from the others of the genus by rostrum deeply recessed, gnathopod 2 with 2 teeth on flexor margin and uropod 1 peduncle with 2–4 robust setae on both medial margins.