The talitrid amphipods of Tonga (Crustacea, Amphipoda, Talitridae) Author Lowry, J. K. Author Bopiah, Arundathi text Zootaxa 2013 3681 4 347 370 journal article 10.11646/zootaxa.3681.4.2 6a348ac2-6af7-42fa-a33d-dfc8d19a9567 1175-5326 249123 28B58895-38AF-4694-8014-B038B2186028 Tongorchestia towneri sp. nov. ( Figs 13–16 ) Type material. Holotype , male, 11.5 mm , AM P.89674 (on SEM stubs MI551–MI556). Paratypes : female AM P.89675 (SEM stub, MI557), 4 males , 4 females and juveniles, AM P.80739, Tufuvai Beach ‘Eua Island , Tonga ( 21°21.650’S 174 °58.143’W ), supralittoral zone, Greg Towner, 27 September 2009 ; 8 females and juveniles, AM P.80740, Ha’aluma Beach, ‘Eua, Tonga ( 21°25.719’S 174°56.799’W ), supralittoral zone, Greg Towner, 29 September 2009 . Additional material examined. 11 males , 34 females and juveniles, AM P.87321, fine sand under narrow fringe of mangroves near Nukuleka, Tongatapu, Tonga ( 21°09’12.75”S 175°07’43.66”W ), dark brown talitrids under leaves and dead algae, J.K. Lowry & G.C.B. Poore, 15 October 2011 . Type locality. Tufuvai Beach ‘Eua, Tonga ( 21°21.650’S 174 °58.143’W ), supralittoral zone. Etymology. Named for Greg Towner, Australian Museum volunteer and collector of the species. Habitat . Beach-hoppers, living among leaves and dead algae in the supralittoral zone. Description. Based on holotype , male, 11.5 mm , AM P.89674. Head. Eyes present. Antenna 1 short, not reaching end of article 4 of antenna 2 peduncle. Antenna 2 up to half body length; peduncular articles incrassate; article 5 subequal to article 4. Mandible left lacinia mobilis 4-dentate. Maxilla 1 with small palp, 2-articulate. Maxilliped palp article 2 distomedial lobe well developed, article 4 reduced, button-shaped. FIGURE 13. Tongorchestia towneri sp. nov. , holotype, male, 11.5 mm, AM P.89674, Tufuvai Beach ‘Eua Island, Tonga. Scale lines for H, MD, MP, MX1, UL, LL represent 100 µm; and MX2 represents 20 µm. FIGURE 14. Tongorchestia towneri sp. nov. , holotype, male, 11.5 mm, AM P.89674, Tufuvai Beach ‘Eua Island, Tonga. Scale lines for G1, P3, P4 represent 100 µm; and G2, P5, P6, P7 represent 200 µm. FIGURE 15. Tongorchestia towneri sp. nov. , paratype, female, AM P. 89675, Tufuvai Beach ‘Eua Island, Tonga. Scale lines for G1, G2 represent 100 µm. Pereon. Gnathopod 1 sexually dimorphic; subchelate; coxa smaller than coxa 2; posterior margin of carpus and propodus each with lobe covered in palmate setae; carpus 1.6 × as long as propodus, 3.1 × as long as broad; propodus 'subtriangular' with well developed posterodistal lobe, anterior margin with 5 groups of robust setae, lateral surface with 9 cuspidate setae, posterolateral surface with 6 serrate setae, medial surface with 7 cuspidate setae, posteromedial surface with 3 serrate setae, posterior margin without cuspidate setae, posterior margin without serrate setae; palm transverse, with 4 serrate setae; dactylus slightly longer than palm. Gnathopod 2 sexually dimorphic; subchelate; basis slender; ischium with rounded lobe on mid-anterior margin, without posterodistal lobe on medial surface; posterior margin of merus, carpus and propodus each without with lobe covered in palmate setae; carpus triangular, reduced (enclosed by merus and propodus), posterior lobe absent, not projecting between merus and propodus; propodus subrhomboidal, 1.3 × as long as wide; palm acute, reaching about 30% along posterior margin, lined with robust setae, evenly rounded, with small proximal sinus, without palmar protuberances; posteromedial surface of propodus with groove; with cuticular patch at corner of palm; dactylus subequal in length to palm, spatulate distally. Pereopods 2–4 coxae wider than deep. Pereopods 3–7 cuspidactylate; without distal patch of many rows of tiny denticles on the anterior margin. Pereopod 4 significantly shorter than pereopod 3; carpus significantly shorter than carpus of pereopod 3; dactylus thickened proximally with a notch midway along the posterior margin; dactylus without anterodistal patch. Pereopod 5 propodus distinctly longer than carpus. Pereopod 6 not sexually dimorphic, shorter than pereopod 7; coxa posterior lobe inner view posteroventral corner rounded, posterior margin perpendicular to ventral margin, posterior lobe with ridge, posterior lobe with 3–4 marginal setae; gill convoluted. Pereopod 7 not sexually dimorphic; basis lateral sulcus present, slightly pronounced, basis posterior margin with numerous small robust setae, posterodistal lobe present, shallow, broadly rounded; merus and carpus slender; merus posterior margin straight. Pleon. Pleopods 1–3 well developed, biramous, rami multiarticulate, inner ramus subequal in length to outer. Epimeron 2 subequal in length to epimeron 3. Epimeron 3 posterior margin smooth, with tiny setae, posteroventral corner subquadrate, ventral margin without robust setae. Uropod 1 not sexually dimorphic, peduncle distolateral robust seta present, small (less than 1/4 length of outer ramus), with simple tip; inner ramus subequal in length to outer ramus, with 5 marginal robust setae; outer ramus with marginal robust setae, with 4 robust setae on margins. Uropod 2 peduncle with 4 robust setae; inner ramus subequal in length to outer ramus, with 5 marginal robust setae; outer ramus with 2 marginal robust setae. Uropod 3 peduncle with 3 robust setae; ramus not fused to peduncle, subequal in length to peduncle, 2.2 × as long as broad, linear (narrowing), with 3 marginal robust setae, with more than 5 apical setae. Telson longer than broad, entire, dorsal midline vestigial or absent, with marginal and apical robust setae, with 7–9 robust setae per lobe. FIGURE 16. Tongorchestia towneri sp. nov. , holotype, male, 11.5 mm, AM P.89674, Tufuvai Beach ‘Eua Island, Tonga. Scale lines for EP, Ur, U1, U2, U3 & T represent 100 µm. Female (sexually dimorphic characters). Based on paratype , female, AM P.89675. Antenna 2 peduncular articles slender. Gnathopod 1 parachelate; posterior margin of merus, carpus and propodus each without lobe covered in palmate setae; propodus subrectangular, anterior margin with 3 groups of robust setae; palm acute, with 5 serrate setae. Gnathopod 2 mitten-shaped; basis expanded proximally; posterior margin of merus, carpus and propodus each with lobe covered in palmate setae; ischium without rounded lobe on mid-anterior margin; 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, without protuberance near dactylar hinge, posterodistal corner without spine; without cuticular patch at corner of palm; dactylus not modified distally. Distribution . ‘Eua; Tongatapu; Tonga .