Talorchestia dili, 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 : 407-411

Talorchestia dili sp. nov.

( Figs 5–8 )

Type material. Holotype, male, 11.4 mm, AM P.90634 (SEM pin and 4 SEM stubs), beach at Monte Veado , west of Tibar, Timor-Leste, (8°33.817'S 125°24.450'E), under small clumps of algae on coarse shell and sand, supralittoral, 20 September 2012, J.K. Lowry, R.E. Golding, M. Hugill, TM 2012-052 . Paratypes: female ovigerous, AM P.90635 (SEM pin and 2 SEM stubs); many specimens, AM P.99067, same data as holotype .

Additional material examined. 15 specimens, AM P.98981, among Posidonia , and brown and red algae on coarse sand and shell beach above broad mud flats and Posidonia meadows, east end of large bay between Dili and Christu Rei, East Timor (8°32.772'S 125°36.384'E), J.K. Lowry, R.E. Golding, 18 September 2012, TM 2012-012. Many specimens, AM P.99712, among leaves, twigs over coarse sand backing large mangrove forest at Gaiteho, Timor-Leste (8°34.103'S 125°26.066'E), J.K. Lowry, 22 September 2012, TM 2012-053. 70 specimens, AM P.97713, under small clumps of algae on fine white sand beach at western end of Christu Rei, Timor-Leste (8°31.358'S 125°36.556'E), J.K. Lowry and R.E. Golding, 23 September 2012, TM 2012-079. 16 specimens, AM P.97710, under small patches of seaweed over coarse black sand along edge of small freshwater stream near the sea, west of Hera, Timor-Leste (8°31.701'S 125°40.231'E), J.K. Lowry and R.E. Golding, 23 September 2012, TM 2012–081.

Type locality. Beach at Monte Veado, west of Tibar, Timor-Leste (8°33.817'S 125°24.450'E).

Habitat. Living among strandline debris on coarse shell and sand beaches in the supralittoral zone.

Etymology. Named for original area of collection, Dili.

Description. Based on holotype, male, 11.4 mm, AM P.90634.

Head. Antenna 2 about as long as body (95%); peduncular articles with marginal row of robust setae, peduncular articles with many small robust setae; article 5 much longer than article 4; flagellar articles final article large, cone-shaped forming a virgula divina, with apical cluster of 'imbricated' setae. Labrum upper lip with apical setal patch; epistome without robust setae, without many pores. Mandible left lacinia mobilis with 5 cusps. Labium distolateral setal tuft absent; without inner plates. Maxilla 1 with small palp, 2-articulate.

Pereon. Gnathopod 1 coxa smaller than coxa 2; carpus 1.7 × as long as propodus, 2.5 × as long as broad; propodus subrectangular, anterior margin with 6 groups of robust setae; dactylus longer than palm, with anterodistal denticular patch. Gnathopod 2 sexually dimorphic; basis anterior margin smooth, slender; ischium with slight rounded lobe on mid-anterior margin, distal triangular anterodistal lobe on medial surface; carpus triangular, reduced (enclosed by merus and propodus), posterior lobe absent, not projecting between merus and propodus; propodus subrhomboidal, 1.8 × as long as wide, palm reaching about 56¾ along posterior margin, smooth, without protuberance near dactylar hinge, lined with robust setae, posteromedial surface of propodus with groove, without cuticular patch at corner of palm; dactylus subequal in length to palm, sinusoidal, without anteroproximal bump, with posteroproximal sinus and stout projection. Pereopods 2–4 coxae wider than deep, or as wide as deep, or deeper than wide. Pereopod 3 dactylus without anterodistal patch. Pereopod 4 significantly shorter than pereopod 3; carpus significantly shorter than carpus of pereopod 3; dactylus without anterodistal denticular patch. Pereopod 5 propodus distinctly longer than carpus; dactylus with anterodistal denticulate patch. Pereopod 6 coxa posterior lobe medial view posteroventral corner rounded, posterior margin oblique to ventral margin, posterior lobe with ridge, with 5 or more marginal setae. 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 longer than epimeron 3. Epimeron 3 posterior margin smooth, with tiny setae, posteroventral corner with small subacute tooth. Uropod 1 peduncle with about 20 robust setae; inner ramus subequal in length to outer with 5 lateral and 7 medial robust setae; outer ramus without marginal robust setae. Uropod 2 peduncle about 16 robust setae; inner ramus subequal in length to outer ramus, with 4 medial and 4 lateral robust setae; outer ramus with 3 marginal robust setae. Uropod 3 peduncle with 9–10 robust setae; ramus not fused to peduncle, ramus 2.2 × as long as broad, ramus linear (narrowing), ramus with 3 marginal robust setae, ramus with more than 5 apical robust setae. Telson dorsal midline complete, 9–10 setae per lobe.

Female (sexually dimorphic characters). Paratype, female, AM P.90635. Antenna 2 more than half but not exceeding body length. Gnathopod 1 carpus 3.3 × as long as broad; propodus anterior margin with 4 groups of robust setae. Gnathopod 2 basis expanded anteroproximally and anterodistally; ischium without lobe on anterior margin, without anterodistal lobe on medial surface; carpus well developed (not enclosed by merus and propodus), posterior lobe present, projecting between merus and propodus; propodus not lined with robust setae; dactylus curved, posterior margin smooth. Oostegites longer than wide (length greater than 2 × width), weakly setose.

Remarks. Talorchestia dili is common to very common on sand beaches in the Dili area of Timor-Leste (personal observations, JKL). It belongs in the species group without a distal protuberance on the palm of male gnathopod 2. This species is geographically nearest to T. martensii ( Weber, 1892) and is similar morphologically, but differs most obviously in the shape of the posteroventral corner of epimeron 3 (small subacute tooth in T. dili and forming a large, acutely produced tooth in T. martensii ).

Distribution. Timor-Leste. East and west of Dili (this study).

Figures

FIGURE 5. Talorchestia dili, holotype, male, 11.4 mm, AM P. 90634, paratype, female ovigerous, AM P. 90635, Monte Veado, west of Tibar, Timor-Leste. Scale lines represent 0.1 mm.

FIGURE 6. Talorchestia dili, holotype, male, 11.4 mm, AM P. 90634, paratype, female ovigerous, AM P. 90635, Monte Veado, west of Tibar, Timor-Leste. Scale line for male G 2 represents 1 mm, remainder 0.5 mm.

FIGURE 7. Talorchestia dili, holotype, male, 11.4 mm, AM P. 90634, Monte Veado, west of Tibar, Timor-Leste. Scale lines represent 0.5 mm.

FIGURE 8. Talorchestia dili, holotype, male, 11.4 mm, AM P. 90634, Monte Veado, west of Tibar, Timor-Leste. Scale lines represent 0.5 mm.