Floresorchestia Bousfield, 1984

Lowry, J. K. & Springthorpe, R. T., 2009, The genus Floresorchestia (Amphipoda: Talitridae) on Cocos (Keeling) and Christmas Islands, Memoirs of Museum Victoria 66 (1), pp. 117-127 : 121-122

Floresorchestia Bousfield, 1984

Orchestia floresiana group Bousfield, 1971: 267.

Floresorchestia Bousfield, 1984: 205 . — Miyamoto & Morino, 2008: 838.

Type species. Orchestia floresiana Weber, 1892 , original designation.

Included species. Floresorchestia includes 14 species: F. ancheidos (K.H. Barnard, 1916) ; F.anomala ( Chevreux, 1901) ; F. anoquesana ( Bousfield, 1971) ; F. anpingensis Miyamoto & Morino, 2008 ; F. floresiana ( Weber, 1892) ; F. guadalupensis Ciavatti, 1989 ; F. hanoiensis Hou & Li, 2003 ; F. monospina ( Stephensen, 1935) ; F. pectenispina ( Bousfield, 1970) ; F. pickeringi ( Dana, 1853) ; F. poorei sp. nov.; F. samoana ( Bousfield, 1971) ; F. vitilevana (J.L. Barnard, 1960) ; F. yehyuensis Miyamoto & Morino, 2008 .

Description. Head. Mandible left lacinia mobilis 5-dentate or 4-dentate. Maxilliped palp article 2 distomedial lobe well developed, article 4 reduced, button-shaped.

Pereon. Gnathopod 1 posterior margin of merus, carpus and propodus each with lobe covered in palmate setae; palm transverse. Gnathopod 2 subchelate. Pereopods 2–4 coxae wider than deep. Pereopods 6–7 longer than pereopods 3–5. Pereopod 6 posterior lobe inner view posteroventral corner subquadrate or posteroventral corner rounded. Pereopod 7 basis posterior margin with distinct minute serrations, each with a small seta.

Pleon. Pleopods all well developed. Pleopod 1 peduncle with or without sparse marginal setae. Pleopod 2 peduncle with or without sparse marginal setae; outer ramus longer than peduncle. Pleopod 3 peduncle with or without marginal robust setae. Epimera 2–3 each with stridulating organs just above ventral margins. Uropod 1 peduncle distolateral robust seta present; inner ramus with marginal robust setae; outer ramus without marginal robust setae or with one long midmedial seta (in male). Uropod 2 not sexually dimorphic; outer ramus with marginal robust setae. Uropod 3 ramus shorter than peduncle. Telson with marginal and apical robust setae.

Female (sexually dimorphic characters). Gnathopod 1 posterior margin of merus, carpus and propodus each without lobe covered in palmate setae; palm slightly acute. Gnathopod 2 mitten-shaped.

Habitat. Supralittoral and terrestrial amphipods of tropical rain forests, mangroves and beaches in the Indo-West Pacific and Caribbean.

Remarks. Floresorchestia belongs to a group of Indo-West Pacific genera which includes Microrchestia Bousfield, 1984 , Platorchestia Bousfield, 1982 , Protorchestia Bousfield, 1982 , Sinorchestia Miyamoto & Morino, 1999 and Talorchestia Dana, 1853 . They all share a 5 dentate left lacinia mobilis, subchelate male gnathopod 2, well developed pleopods and uropod 1 without marginal robust setae on the outer ramus (except Sinorchestia nipponensis which has marginal robust setae on the outer ramus). Within the group Floresorchestia , Platorchestia , Sinorchestia and Talorchestia have cuspidactylate pereopods. Only Floresorchestia and Platorchestia have the reduced button-shaped fourth articles on the palps of the maxilliped and distally attenuated dactyli on male second gnathopods. Both of these genera have wide distributions.

Floresorchestia monospina ( Stephensen, 1935) and F. pectenispina ( Bousfield, 1970) differ from other species in the genus in having a long, marginal slender robust seta with a modified tip on the outer ramus of male uropod 1 ( Bousfield 1970). Floresorchestia hanoiensis Hou & Li, 2003 , F. malayensis (Tattersall, 1921) , F. samoana ( Bousfield, 1971) and F.vitilevana (J.L. Barnard, 1960) differ from other species in the genus in not having stridulating organs on epimera 2 and 3. In other respects these species appear to be Floresorchestia and F. hanoiensis has pitting on the face of epimera 1 and 2. Floresorchestia pickeringi ( Dana, 1853) needs to be redescribed to confirm its status in the genus.

Floresorchestia ancheidos (K.H. Barnard, 1916) , F. anomala ( Chevreux, 1901) and F. floresiana ( Weber, 1892) , type species of the genus, are all poorly described species and F. anomala and F. floresiana are the source of questionable synonymies from wide-ranging localities. These species also need to be redescribed based on new material from the type localities using modern characters as outlined by Miyamoto & Morino (2008) before realistic distributions for species in the genus can be determined.