Talorchestia bunaken, Azman, B. A. R., 2017

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 : 403-406

Talorchestia bunaken sp. nov.

( Figs 1–4 )

Type material. Holotype, male, 10.1 mm, UKMMZ-1404 (SEM pin and 4 SEM stubs), Bunaken Island , Northern Sulawesi, Indonesia (1°37.2'N 124°45.25'E), beach, supralittoral zone, B.A.R. Azman, 16 May 2009 . Paratypes: 4 females, UKMMZ-1407; 1 male, 7 females, UKMMZ-1408, same data as holotype .

Type locality. Bunaken Island , Northern Sulawesi, Indonesia (1°37.2'N 124°45.25'E).

Ecological type. Beach-hoppers (mainly coastal supralittoral/intertidal leaf-litter/wrack, non-substrate modifying talitrids).

Etymology. Named for the type locality, Bunaken Island.

Description. Based on holotype, male, 10.1 mm UKMMZ-1404.

Head. Ventroproximal surface with 6 or 7 groups of slender scales. Antenna 2 slightly more than half body length (56%); peduncular articles with marginal row of small, robust setae; article 5 slightly longer than article 4; flagellum final article large, cone-shaped forming a virgula divina, with apical cluster of 'imbricated' setae. Labrum with apical setal patch; epistome without robust setae, without many pores. Mandible left lacinia mobilis with 5 cusps. Labium distolateral setal tuft present; without inner plates. Maxilla 1 with small palp, 2-articulate.

Pereon. Gnathopod 1 coxa smaller than coxa 2; carpus 1.6 × as long as propodus, 2.4 × as long as broad; propodus subrectangular, anterior margin with 5 groups of robust setae, palm with 3 serrate setae, without spine patch on posterodistal corner; dactylus longer than palm, without anterodistal denticular patch. Gnathopod 2 sexually dimorphic; basis slender, anterior margin minutely serrate; ischium without lobe on anterior margin, with distally rounded anterodistal lobe on medial surface; carpus triangular, reduced (enclosed by merus and propodus), posterior lobe absent, not projecting between merus and propodus; propodus subovate, 1.8 × as long as wide, palm reaching about 75% along posterior margin, smooth, with strong rounded protuberance near dactylar hinge, lined with (9 + 3) medial robust setae, posteromedial surface of propodus with groove, without cuticular patch at corner of palm; dactylus longer than palm, sinusoidal, without anteroproximal bump, posterior margin lined with small robust setae, with small posteroproximal sinus and small projection. Pereopods 2–4 coxae wider than deep or as wide as deep. Pereopods 3–7 dactyli without anterodistal patch of many rows of tiny setae. Pereopod 4 significantly shorter than pereopod 3. Pereopod 5 propodus distinctly longer than carpus; dactylus without anterodistal setal patch. Pereopod 7 basis lateral sulcus present, slightly pronounced, posterodistal lobe absent; distal articles (merus and carpus) slender; merus posterior margin straight.

Pleon. Epimeron 1 robust setae along ventral margin absent. Epimeron 2 subequal in length to epimeron 3. Epimeron 3 posterior margin minutely serrate, with 3 minute setae, posteroventral corner with small subacute tooth. Uropod 1 peduncle with about 12 robust setae, distolateral robust seta large (about 1/4 length of outer ramus); inner ramus subequal in length to outer ramus, with 4 medial and 4 lateral robust setae. Uropod 2 peduncle with 8 robust setae; inner ramus subequal in length to outer ramus, with 3 medial and 3 lateral robust setae; outer ramus with 1 marginal robust seta. Uropod 3 peduncle with 6 robust setae; ramus partially fused to peduncle, about 2.3 × as long as broad, ramus linear (narrowing), ramus with 4 marginal robust setae, ramus with more than 5 apical robust setae. Telson dorsal midline complete, with about 7 setae per lobe.

Habitat. Sandy beaches.

Remarks. Talorchestia bunaken sp. nov. belongs to the group of species with a prominent palmar protuberance near the dactylar hinge on male gnathopod 2. It shares with T. yoyoae , a very long palm on male gnathopod 2, reaching about 75–78¾ along the posterior margin of the propodus. Talorchestia bunaken differs from T. yoyoae in having a 5 or 6 cusps (sixth minute) on the left lacinia (6 cusps in T. yoyoae ), in the gnathopod 1 carpus which is about 2.5 × as long as broad (3 × in T. yoyoae ) and the uropod 3 ramus which is subequal to the peduncle in T. bunaken (shorter in T. yoyoae ).

Distribution. Indonesia. Bunaken Island, Northern Sulawesi (this study).

Figures

FIGURE 1. Talorchestia bunaken, holotype, male, 10.1 mm, UKMMZ- 1404, Bunaken Island, Northern Sulawesi, Indonesia. Scale lines represent 0.1 mm.

FIGURE 2. Talorchestia bunaken, holotype, male, 10.1 mm, UKMMZ- 1404, Bunaken Island, Northern Sulawesi, Indonesia. Scale lines represent 0.5 mm.

FIGURE 3. Talorchestia bunaken, holotype, male, 10.1 mm, UKMMZ- 1404, Bunaken Island, Northern Sulawesi, Indonesia. Scale lines represent 0.5 mm.

FIGURE 4. Talorchestia bunaken, holotype, male, 10.1 mm, UKMMZ- 1404, Bunaken Island, Northern Sulawesi, Indonesia. Scale lines for U 1, U 2, T represent 0.1 mm, remainder represent 0.5 mm.