Platorchestia platensis

Habitat. In beach algal debris on high shore of protected beaches.

Sumber: The Beach-hopper Genus Platorchestia (Crustacea: Amphipoda: Talitridae) on Atlantic Ocean Coasts and on those of Associated Seas

Description. Male (based on adult male, 14 mm). Head. Eyes black, medium size. Antenna 1 short, not longer than article 4 of antenna 2. Antenna 2 peduncle incrassate; article 5 longer than 4; peduncular articles with sparse, small robust setae. Pereon. Gnathopod 1; subchelate; posterior margin of carpus and propodus with rugose lobe; carpus of moderate length, about two-and-a-half × as long as its broadest width and about one and one quarter length of propodus, rugose lobe broad; propodus palm transverse; dactylus weakly overlapping palm, cuspidactylate. Gnathopod 2 sexually dimorphic; subchelate; basis weakly expanded, subrectangular; merus without medial lobe; carpus reduced, enclosed by merus and propodus; propodus posterior margin nearly straight, palm acute, with sinuous margin and subdistal notch, posterodistal corner with protuberance; dactylus scythiform, overlapping posterior margin. Coxae 2 – 4 as wide as deep. Pereopods 3 – 7 cuspidactylate. Pereopod 4 significantly shorter than pereopod 3; dactylus thickened different from that of pereopod 3. Pereopod 5 propodus distinctly longer than carpus. Pereopod 6 not sexually dimorphic, shorter than pereopod 7; coxa posterior lobe with weak serrations and posteroproximal corner extended into a distinct lobe. Pereopod 7 sexually dimorphic; basis almost as broad as long, posterodistal lobe present; carpus elongate suboval, length 1.6 × breadth, anterior margin weakly crenulate; carpus: propodus length ratio = 5: 6. Pleon. Epimera 1 – 3 with posterior margin slightly scalloped; posteroventral corner of epimera 2 – 3 moderately produced, subacute. Uropod 1 peduncle 1.5 × length of rami, with robust setae in two rows, distolateral robust seta weak; endopod subequal in length to exopod and with 3 marginal inner robust setae and 4 marginal outer robust setae; endopod without marginal robust setae. Uropod 2 peduncle inner margin with about 5 robust setae and outer margin with 3 robust setae; inner ramus subequal in length to exopodite; endopodite with 2 marginal inner robust setae, exopodite with 2 marginal robust setae. Uropod 3 peduncle 1.5 × length of ramus, with 2 or 3 robust setae; ramus stout, less than 3 × longer than broad, with 0 - 2 marginal setae, and 3 or 4 apical setae. Telson longer than broad, apically incised, with marginal and apical robust setae; each lobe with 3 – 5 robust setae. Female (sexually dimorphic characters). Antennae 2 slender, not incrassate, Gnathopod 1 without rugose lobes on carpus and propodus. Gnathopod 2 mitten-shaped; basis anterior margin strongly convex proximally, weakly concave anteriorly. Pereopod 7 carpus slender.