Platorchestia

Serejo, Cristiana S., 2004, Talitridae (Amphipoda, Gammaridea) from the Brazilian coastline, Zootaxa 646, pp. 1-29 : 26-27

Key to the Brazilian coastline talitrid species and some sibling species within Platorchestia

1. Male gnathopod 1 simple; pereopod 5 with 3–4 very robust round­tipped setae on anterior margin of carpus, dactylus thick and distinct from the others; pleopods 1–3 reduced, uniramous ............................... Atlantorchestoidea brasiliensis ( Dana, 1853)

­ Male gnathopod 1 subchelate; pereopod 5 with pointed­tipped robust setae on anterior margin of carpus, dactylus not thickened, similar to the others; pleopods 1–3 not

reduced, biramous ........................................................................................................ 2 2. Female gnathopod 1 simple; palm of male gnathopod 2 with a well developed proximal concavity and a corresponding process on the dactylus; dorsal margin of outer ramus of uropod 1 with robust setae ............. “ Talorchestia ” tucurauna ( Müller, 1864)

­ Female gnathopod 1 subchelate (palm short); palm of male gnathopod 2 not as above; outer ramus of uropod 1 lacking marginal robust setae .............................................. 3

3. Male antenna 2 with peduncle articles 4–5 incrassate; male gnathopod 1, merus lacking posterior lobe; dactylus cuspidactylate; uropod 1 lacking disto­lateral robust setae; ramus of uropod 3 subequal or slightly smaller than peduncle; basis of female gnathopod 2 anteriorly expanded (in juveniles it is not so expanded) ................................... 4

­ Male antenna 2 not incrassate; male gnathopod 1, merus with posterior lobe; dactylus simplydactylate; uropod 1 with a distinct disto­lateral robust setae; ramus of uropod 3 half length of peduncle; basis of female gnathopod 2 not expanded ............................. ............................................................................ Chelorchestia darwini ( Müller, 1864)

4. Coxae2–4shallow,much wider than deep; dactylus of male gnathopod 1subequal to palm ....................................................................................... Platorchestia munmui Jo, 1988

­ Coxae 2–4 as wide as deep; dactylus of male gnathopod 1 distinctly shorter than palm ....................................................................................................................................... 6

5. Male pereopod 7 incrassate; oostegite 5 posterior margin with less setae than anterior margin .............................................................. Platorchestia platensis (Kroyer, 1845)

­ Male pereopod 7 not incrassate; oostegite 5 posterior and anterior margin with about the same number of setae ............................. Platorchestia monodi Mateus et al. 1986