Atlantorchestoidea

Serejo, Cristiana S., 2004, Talitridae (Amphipoda, Gammaridea) from the Brazilian coastline, Zootaxa 646, pp. 1-29 : 8-9

Atlantorchestoidea gen nov.

Diagnosis. Male antenna 2 not incrassate, peduncle article 4 about half length of article 5. Left lacinia mobilis 4­dentate. Coxae 2–4 deeper than wide with distinct posterior process. Pereopod 5 shorter than pereopods 6–7, anterior margin of carpus with 3–4 long truncated robust setae, dactylus robust and short, distinct of that of pereopods 6–7. Pleopods 1–3 uniramous, strongly reduced and decreasing in size, each ramus 1­articulate. Ramus of uropod 3 about 1.7 times peduncle length. Telson wider than long and with a pair of robust setae on each margin.

Type species. Orchestia (Talitrus) brasiliensis Dana, 1853 (by monotypy).

Remarks. Within the sandhoppers, Atlantorchestoidea gen. nov. is similar to Orchestoidea and Pseudorchestoidea as follows: peduncle of male antenna 2 not incrassate; left lacinia mobilis 4­dentate; and male and female gnathopod 1 simple. The new genus has also other similarities to Orchestoidea such as coxae 2–4 deeper than wide; coxa 6 with a deep posterior lobe; telson wider than long, distally rounded; and basis of female gnathopod 2 not or little expanded. Atlantorchestoidea can be distinguished from these two genera by the characteristic robust anterior setae on carpus of pereopod 5; and the highly modified pleopods 1–3, which are reduced, uniramous, with each ramus 1­articulate. Compiled information on morphological distinctions between these three genera are given in Table 1 .

Etymology. The generic name, Atlantorchestoidea , is a combination of Atlantic and Orchestoidea .

Characters Orchestoidea Pseudorchetoidea Atlantorchestoidea gen. nov.