Floresorchestia palau Lowry, 2013, sp. nov.
Creators: name: Lowry, J. K.
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Talitridae
Floresorchestia
Floresorchestia palau

description: Floresorchestia palau sp. nov.
(Figs 1, 2)
Type material. Holotype, male, 3.5 mm, OUMNH.ZC. 2002-24 -0118, inside Pinchers Lagoon, western edge of Malakal Harbour, Malakal Island, Koror, Palau, Micronesia (07°20.407' N 134°25.755'E), light trap sample, sandy callianassid flat, 3 m depth, S. De Grave & C. Burras, night 27–28 May 2002.
Additional material examined. 1 female (dissected, lost), same locality as holotype. 19 specimens, AM P.88295, under leaf litter just above high tide mark underneath mangrove branches on sandy/silty beach, 50 m east of the end of the main road northern end of Pelelieu Island, Palau, Micronesia, (7°2'52"N 134°16'10"E), G. Towner, 2 April 2012.
Type locality. Inside Pinchers Lagoon, western edge of Malakal Harbour, sandy flat, 3 m depth (07°20.407' N, 134°25.755'E).
Etymology. Named for the type locality.
Habitat. Beach-hopper, living in the supralittoral zone beneath mangrove branches on sandy/silty beach and found at 3 m depth in marine environment.
Description. Based on holotype, male, 3.5 mm.
Head. Eye medium (1/5–1/3 head length). Antenna 1 short, slightly longer than article 4 of antenna 2 peduncle. Antenna 2 shorter than head and first 3 pereonites; peduncular articles slender, article 5 longer than article 4. Mandible left lacinia mobilis 4-dentate. Maxilla 1 with well developed palp. Maxilliped palp article 2 distomedial lobe well developed; article 4 reduced, button-shaped.
Pereon. Gnathopod 1 sexually dimorphic; subchelate; coxa smaller than coxa 2; posterior margin of merus (palmate lobe vestigial), carpus and propodus each with lobe covered in palmate setae, palmate lobes in male only; propodus subtriangular, anterior margin with 3 groups of robust setae; dactylus subequal in length to palm, palm transverse. Gnathopod 2 sexually dimorphic; subchelate; basis slightly expanded, anterior margin smooth; ischium with anterodistal cradle; merus with distally rounded posterodistal lobe on medial surface; posterior margin of merus, carpus and propodus each without lobe covered in palmate setae; carpus triangular, reduced (enclosed by merus and propodus), posterior lobe absent, not projecting between merus and propodus; propodus subovate, 1.6 × as long as wide; palm acute, reaching about 45% along posterior margin, smooth, lined with robust setae, posterodistal corner with groove, with cuticular patch at corner of palm; dactylus longer than palm, attenuated distally. Pereopods 2–4 coxae wider than deep, or as wide as deep. Pereopods 3–7 cuspidactylate. Pereopod 4 subequal or slightly shorter than pereopod 3; carpus similar in length to pereopod 3 carpus; dactylus similar to pereopod 3 dactylus. Pereopod 5 propodus distinctly longer than carpus. Pereopods 6–7 long, nearly 1/2 length of body, longer than pereopods 3–5. Pereopod 6 slightly shorter than pereopod 7; posterior lobe inner view posteroventral corner rounded, posterior margin perpendicular to ventral margin, posterior lobe without ridge, with 1–2 marginal setae. Pereopod 7 basis lateral sulcus absent, basis posterior margin with distinct minute serrations, each with a small seta, posterodistal lobe absent; merus and carpus slender; merus posterior margin evenly rounded; propodus setation without large distal tuft of setae.
Pleon. Pleopods1–3 all biramous, well developed. Epimera 2–3 each with vertical slits just above ventral margins. Epimera 2 with 17 slits, subequal in length to epimeron 3. Epimeron 3 with at least 12 slits, posterior margin smooth, without setae, posteroventral corner with small subacute tooth, ventral margin without setae. Uropod 1 peduncle with 6 robust setae, distolateral robust seta absent; inner ramus subequal in length to outer ramus, inner ramus with 2 marginal robust setae (1 row); outer ramus without marginal robust setae. Uropod 2 peduncle with 3 robust setae; inner ramus subequal in length to outer ramus, without marginal robust setae; outer ramus without marginal robust setae. Uropod 3 peduncle with 1 robust setae; ramus shorter than peduncle, linear (narrowing), with 3 apical setae. Telson about as broad as long, apically incised, dorsal midline entire, with 2 marginal and apical robust setae per lobe.
Female (sexually dimorphic characters). Gnathopod 1 posterior margin of merus, carpus and propodus each without lobe covered in palmate setae; anterior margin with 2 groups of robust setae; palm slightly acute. Gnathopod 2 mitten-shaped; posterior margin of carpus and propodus each with lobe covered in palmate setae; carpus well developed, posterior lobe projecting between merus and propodus; nearly twice as long as wide; palm obtuse, not lined with robust setae, posterodistal corner without spine, without cuticular patch at corner of palm; dactylus subequal in length to palm, not modified distally, blunt.
Remarks. Floresorchestia palau is characterised by a 4-dentate left lacinia mobilis, male gnathopod 1 with palmate lobes on the merus (vestigial), carpus and propodus, epimera 2–3 with vertical slits, and uropod 3 ramus without marginal setae. The only other similar species is F. hanoiensis Hou & Li, 2003 (Hou, pers com, has confirmed vertical slits on epimera 2 and 3). Floresorchestia palau differs from this species in a number of ways including having no setae on the rami of uropod 2 (setose in F. hanoiensis), only one robust seta on the peduncle of uropod 3 (two in F. hanoiensis) and only two setae per lobe on the telson (three in F. hanoiensis).
Distribution. Micronesia. Palau.
description: Published as part of Lowry, J. K., 2013, New species of Floresorchestia from Micronesia living in unusual habitats (Crustacea, Amphipoda, Talitridae), pp. 576-584 in Zootaxa 3737 (5) on pages 577-580, DOI: 10.11646/zootaxa.3737.5.4, http://zenodo.org/record/218191