Talorchestia Dana, 1852b

Azman, B. A. R., 2017, The talitrid amphipod genus Talorchestia from the South China Sea to the Indonesian Archipelago (Crustacea, Senticaudata), Zootaxa 4319 (3), pp. 401-434 : 402-403

Talorchestia Dana, 1852b

Orchestia (Talorchestia) Dana, 1852b: 310 .— Dana, 1853: 851.— Spence Bate, 1857: 135.

Talorchestia .— Stebbing, 1888: 262 (in part).— Stebbing, 1891: 328 (in part).— Chevreux, 1893: 127.— Stebbing, 1906: 543 (in part).— Stephensen, 1948: 7 (in part).— Hurley, 1956: 359 (in part.).— Morino & Miyamoto, 1988: 91.— Miyamoto & Morino, 1999: 170.— Lowry & Springthorpe, 2009: 905.

Talorchestes , Thalorchestia .— Filhol, 1885: 459, 461, planches 28 [not seen].

Type species. Talitrus gracilis Dana, 1852a , monotypy.

Included species. Talorchestia includes 14 species: T. brucei Lowry & Springthorpe, 2009 ; T. bunaken sp. nov.; T. dampieri Lowry & Springthorpe, 2015b ; T. dili sp. nov.; T. gracilis Dana, 1852a ; T. martensii ( Weber, 1892) ; T. mindorensis Oleröd, 1970 ; T. morinoi Othman & Azman, 2007 ; T. qeshm Lowry & Momtazi, 2015 ; T. seringat sp. nov.; T. sipadan sp. nov.; T. spinipalma Dana, 1852a ; T. terraereginae Haswell, 1880 ; and T. yoyoae sp. nov.

Diagnostic description. Head. Eye medium (1/5–1/3 head length), or large (greater than 1/3 head length). Antenna 1 short, rarely longer than peduncular article 4 of antenna 2. Antenna 2 peduncular articles slender, article 3 without plate or process ventrally; flagellum final article large, cone-shaped forming a virgula divina, with apical cluster of 'imbricated' setae. Mandible left lacinia mobilis with 5 or 6 cusps (sixth minute). Maxilliped palp article 2 distomedial lobe well developed; article 4 fused with article 3.

Pereon. Gnathopod 1 parachelate; posterior margin of carpus and propodus each with lobe covered in palmate setae; palm transverse or obtuse. Gnathopod 2 subchelate; carpus and propodus each without lobe covered in palmate setae; dactylus not modified distally, blunt, shorter than propodus. Pereopods 3–7 cuspidactylate. Pereopod 4 dactylus thickened proximally with a notch midway along posterior margin. Pereopod 5 dactylus long, slender. Pereopod 6 subequal or shorter than 7. Pereopods 6 –7 not sexually dimorphic.

Pleon. Pleonite 1–3 without dorsal spines. Pleopods all well developed, biramous. Epimera 1–3 without slits just above ventral margins. Uropod 1 peduncle distolateral robust seta present or absent, rami without apical spear-shaped setae; inner ramus with marginal robust setae in 1 or 2 rows; outer ramus without marginal robust setae. Uropod 2 rami without apical spear-shaped setae; inner ramus with marginal robust setae in 2 rows; outer ramus with marginal robust setae in 1 row. Uropod 3 ramus subequal in length or shorter than peduncle. Telson longer than broad, tapering distally, apically incised, with 3–10 marginal and apical robust setae per lobe.

Remarks. Based on the short first antenna, male parachelate gnathopod 1 with palmate lobes on the carpus and propodus, pereopod 5 with slender dactylus, not inflated, uropods 1–2 without spear-shaped seta and uropod 1 without robust setae on the outer ramus Talorchestia Dana, 1852b and Sinorchestia Miyamoto & Morino, 1999 are very similar genera. Sinorchestia overlaps with Talorchestia in Taiwan. It is clearly distinguished from the all other genera by the ventral plate on peduncular article 3 of antenna 2.

Talorchestia also appears to be very similar to the not so well know genus Vietorchestia Dang & Le, 2011 . In characters that are known Vietorchestia has a distinctively shaped gnathopod 2. Two characters separate these genera: the maxilliped palp article 2 has a well-developed medial lobe in Talorchestia (a straight margin in Vietorchestia ) and the uropod 2 inner ramus has one row of marginal robust setae in Vietorchestia (two rows in Talorchestia ).