Floresorchestia poorei, Lowry & Springthorpe, 2009

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 : 122-123

Floresorchestia poorei sp. nov.

( Figures 1 – 7 )

Material examined. Holotype: Indian Ocean , Cocos (Keeling) Islands, West Island, Rumah Baru, (12°09'22"S 96°49'41"E), beach wrack, J.K. Lowry and K.B. Attwood, 8 Oct 2008, (stn MI WA 819), AM P80192 (ovigerous female, 9.2 mm).

Paratypes:type locality, AM P80193 (male,11.7 mm) ; AM P80194 (many specimens) ; AM P80532 (female) ; AM P80543 (female) ; AM P80544 (male) ; AM P80549 (male) .

Other material: Indian Ocean , Cocos (Keeling) Islands, West Island , Government House Beach, (12°05'04"S 96°52'54"E), sand beach, J.K. Lowry, L.E. Hughes and K.B. Attwood, 7 Oct 2008, (stn MI WA 780), AM P.80545 (many specimens). Indian Ocean, Cocos (Keeling) Islands, West Island, beach near “Two Trees dive site”, (12°05'04"S 96°52'54"E), J.K. Lowry, L.E. Hughes and K.B. Attwood, 7 Oct 2008, (stn MI WA 779), AM P.80547 (6 males, 7 females) .

Type locality. Rumah Baru , West Island, Cocos (Keeling) Islands, Indian Ocean (12°09'22"S 96°49'41"E) .

Etymology. Named for our good friend Gary Poore in thanks for his help over the years and in recognition of his immense contribution to the field of carcinology.

Description. Based on holotype, ovigerous female, AM P80192.

Head. Eye large (greater than 1/3 head length). Antenna 1 short, rarely longer than article 4 of antenna 2 peduncle. Antenna 2 up to half body length; peduncular articles narrow; article 5 longer than article 4. Mandible left lacinia mobilis 5-dentate. Maxilliped palp article 2 distomedial lobe well developed, 4 reduced, button-shaped.

Pereon. Gnathopod 1 sexually dimorphic; parachelate; coxa 1 smaller than coxa 2; posterior margin of merus, carpus and propodus each without lobe covered in palmate setae, in male only; propodus subrectangular, propodus posterior margin with 3 cuspidate setae along posterior margin, propodus posterior margin with 3 serrate setae along posterior margin; palm acute, palm with 4 serrate setae; dactylus longer than palm. Gnathopod 2 sexually dimorphic; mitten-shaped; coxal gill simple or slightly lobate; basis anterior margin smooth, basis expanded proximally; ischium without posterodistal lobe on medial surface; posterior margin of merus, carpus and propodus each with lobe covered in palmate setae; carpus well developed (not enclosed by merus and propodus), posterior lobe present, projecting between merus and propodus; palm obtuse, smooth, not lined with robust setae, palm without patch of tiny denticles at corner of palm; dactylus subequal in length to palm, not attenuated distally; gill simple, not incised. Pereopods 2–4 coxae wider than deep. Pereopods 3–7 cuspidactylate. Pereopod 4 subequal or slightly shorter than pereopod 3; carpus significantly shorter than carpus of pereopod 3; dactylus thickened proximally with a notch midway along the posterior margin. Pereopod 5 propodus distinctly longer than carpus. Pereopods 6–7 longer than pereopods 3–5. Pereopod 6 not sexually dimorphic; slightly shorter than pereopod 7; posterior lobe inner view posteroventral corner rounded, posterior margin perpendicular to ventral margin, posterior lobe with ridge, posterior lobe with 1–2 marginal setae. Pereopod 7 not sexually dimorphic; basis lateral sulcus absent, basis posterior margin with distinct minute serrations, each with a small seta, posterodistal lobe present, shallow, broadly rounded; distal articles (merus and carpus) slender; merus posterior margin evenly rounded; propodus setation without large distal tuft of setae. Oostegites long (length greater than 2 x width), longer than wide, weakly setose (6–11 setae), setae with spatulate tips.

Pleon. Pleopods all well developed. Pleopod 1 peduncle with marginal slender setae; biramous, outer ramus shorter than peduncle, inner ramus subequal in length to outer; inner ramus with 9 articles; outer ramus with 6 articles. Pleopod 2 peduncle with marginal slender setae; biramous, inner ramus subequal in length to outer, outer ramus shorter than peduncle; inner ramus with 7 articles. Pleopod 3 peduncle without marginal setae. Pleopod 3 biramous, inner ramus subequal in length to outer, outer ramus shorter than peduncle; rami multarticulate; inner ramus with 6 articles; outer ramus with 6 articles. Epimera 2–3 each with a stridulating organ just above ventral margins. Epimera 2 subequal in length to epimeron 3, with 27 ridges. Epimera 3 with 17 ridges, posterior margin smooth, without setae, posteroventral corner with small subacute tooth, ventral margin without robust setae. Uropod 1 not sexually dimorphic, peduncle with 8 robust setae, distolateral robust seta small; with simple tip; inner ramus subequal in length to outer ramus, with 3 marginal robust setae; outer ramus without marginal robust setae. Uropod 2 not sexually dimorphic; peduncle with 6 robust setae; inner ramus subequal in length to outer ramus, with 2 marginal robust setae; 1 marginal robust setae. Uropod 3 peduncle with 3 robust setae; ramus shorter than peduncle, ramus linear (narrowing), with 2 marginal robust setae, with 4–5 apical setae. Telson longer than broad, completely cleft, with 5 marginal and apical robust setae per lobe.

Male (sexually dimorphic characters). Based on male, AM P80193. Gnathopod 1 subchelate, posterior margin of merus, carpus and propodus each with lobe covered in palmate setae; propodus subtriangular with well developed posterodistal lobe, anterior margin with 3 groups of robust setae, lateral surface with 2 cuspidate setae, posterolateral surface with 5 serrate setae, propodus posterior margin without cuspidate or serrate setae along posterior margin; palm transverse, dactylus subequal in length to palm. Gnathopod 2 subchelate; basis slightly expanded; ischium distal triangular 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; propodus twice as long as wide; palm acute, lined with robust setae; palm with cuticular patch of tiny denticles at corner of palm, posteromedial surface of propodus with groove; dactylus longer than palm, attenuated distally.

Habitat. Living in the supralittoral zone on sheltered beaches under seaweeds and debris.

Remarks. Floresorchestia poorei is currently the only species in the genus with a fully cleft telson.

Distribution. North-Eastern Indian Ocean. Cocos (Keeling) Islands (current study).

Figures

Figure 1. Floresorchestia poorei sp. nov., A−B, paratype, female,AM P80543: left mandible; B, left mandible incisor; C, paratype, female,AM P80543: maxilliped palp article 4. D−J, paratype, male,AM P80544: male gnathopod 1; E, propodus posterolateral serrate seta; F, propodus posterolateral serrate setae; G, palm and dactylus showing cuspidate setae along palm; H, merus showing posterior lobe covered in palmate setae; I, propodus lateral cuspidate seta; J, carpus showing posterior lobe covered in palmate setae. Scale bars:A, B and D represent 100 μm, C represents 50 μm.