Polyrhachis constructor Smith, 1857

Jaitrong, Weeyawat, Yamane, Seiki & Noon-Anant, Nawee, 2023, The Thai species of the Polyrhachis (Myrmatopa) flavicornis Smith, 1857 species group, with description of a new species (Hymenoptera, Formicidae Formicinae), Zootaxa 5249 (4), pp. 446-464 : 448-451

Polyrhachis constructor Smith, 1857

( Figs 1–3 )

Polyrhachis constructor Smith, 1857 , queen, Borneo: 60; Donisthorpe 1932: 445; Bolton 1995: 43; Pfeiffer et al. 2011: 41.

Polyrhachis piliventris Smith, 1858: 60 , pl. 4, fig. 24, queen, Singapore; Bolton, 1995: 354; Dorow, 1995: 44; Khachonpisitsak et al. 2020: 72; Wang et al. 2022: 10. Syn. nov.

Polyrhachis elii Emery, 1900: 711 , worker, Mentawai Is.; Emery, 1925: 180 (combination in P. ( Myrmatopa )); Kohout and Mohamed 2008: 67; Pfeiffer et al. 2011: 41. Syn. nov.

Types examined. The syntype alate queen of Polyrhachis constructor from East Malaysia, Borneo, Sarawak (A.R. Wallace), deposited in OXUM. The syntype alate queen of Polyrhachis piliventris from Singapore (A.R. Wallace), deposited in BMNH. Two syntype workers of Polyrhachis elii from Indonesia, Mentawai Island, Sipora , Sereinu , V–VI.1894 (E. Modigliani), deposited in MCSN.

Non-type material examined. S Thailand: Songkhla Prov., Ton Nga Chang W.S . 100– 300 m a.s.l., nesting on lower vegetation, 2.40 m above ground, 22.V.2004, N. Noon-anant leg., Colony B (workers, PSUSC, THNHM) ; Phangnga Prov., Lampi Waterfall , 0– 100 m, nesting on lower vegetation, 2.20 m above ground, 19.IV.2005, N. Noon-anant leg., Colony C (workers, queen, PSUSC) ; Trang Prov., Pak Jam Waterfall 130– 190 m a.s.l., nesting on lower vegetation, 1.83 m above ground, 28.II.2006, N. Noon-anant leg., Colony D (workers, PSUSC, THNHM) ; Prachuab Khiri Khan Prov., Pala U Waterfall , 220– 350 m a.s.l., nesting on lower vegetation, 2.00 m above ground, 29.I.2007, N. Noon-anant leg., Colony E (workers, queens, PSUSC, THNHM) ; Prajuab Khiri Khan Prov., Pala U Waterfall 220– 350 m a.s.l., nesting on lower vegetation, 2.80 m above ground, 30.I.2007, N. Noon-anant leg., Colony F (workers, queen). W Thailand: Petchaburi Prov., Kaeng Krachan National Park , 350 m alt., 26.VI.2014, Sk. Yamane, N. Noon-anant & M. Maruyama leg., KK14-Pol-06 (workers and foundress queen). E Malaysia: Borneo, Sabah , Tawu Hills N.P., 12.VII.1996, Sk. Yamane leg., TH14-SKY-Colony A (worker, queen, SKYC) ; Sabah, Danum Valley , 14–19.XII.2006, Ant-mimic sample, 18-e9 (worker, SKYC) .

Measurements and indices. Worker (17 non-types). TL 7.25–7.55, HL 1.33–1.87, HW 1.03–1.57, SL 1.83– 2.77, PW 0.83–1.33, MTL 1.90–2.67, CI 74–86, SI 171–184. Syntype worker ( Polyrhachis elii ). TL 7.25–7.30, HL 1.77–1.90, HW 1.47–1.50, SL 2.57–2.60, PW 1.03–1.27, MTL 2.47–2.67 CI 78–83, SI 173–175. Queen (2 syntypes, 6 non-types). TL 8.85–9.15, HL 1.90–2.20, HW 1.53–1.70, SL 2.80–3.07, PW 1.73–1.87, MTL 2.67–3.13, CI 75–77, SI 175–191.

Description of worker ( Figs. 1 A–C , 3 A–C )

Head in full-face view distinctly longer than broad with posterior margin roundly convex. Clypeus in dorsal view, broad and weakly convex median portion, its anterior margin broadly convex; median portion of anterior margin produced with a pair of short lateral teeth, and margin between teeth almost straight. Frontal carinae in lateral view well elevated, in full-face view weakly sinuate, and reaching level of mid-length of eye. Mandible subtriangular, its masticatory margin with five distinct teeth (including basal and apical teeth). Antennal scape long, clavate, ca. 1.6 times as long as head width including eyes. Eye in full-face view convex, distinctly protruding from the lateral outline of head and located just posterior to mid-length of head laterally.

Pronotum in dorsal view broader than long, with convex lateral margins, humerus armed with short but sharp tooth; anterior margin of pronotal disc weakly convex and posterior margin concave; lateral face of pronotum subtriangular. Mesonotum in dorsal view subtrapezoidal, slightly broader than long, distinctly narrowed posteriad, shorter and narrower than pronotum; mesopleuron rectangular in profile shorter than high, with posteroventral corner roundly lobate. Propodeum in dorsal view rectangular, broader than long, not demarcated from posterior declivity by transverse carina; propodeal spines blunt, short, and pointed upward.

Petiolar node (excluding spines) in dorsal view without distinct dorsum; in profile view almost as long as high, tapered apically with posterior slope much longer than anterior slope; petiolar spines in dorsal view divergent, in lateral view slightly curved backwards, as long as the height of petiole; subpetiolar process weakly developed, posteriorly angulate or with small denticle.

Mandible densely and very minutely puncto-striate but weakly shiny. Vertex and frons of head densely macropunctate; clypeus, antenna, and legs micropunctate; lateral faces of mesosoma and petiole densely macropunctate; petiolar spines micropunctate; pronotum longitudinally weakly striate; mesonotum and dorsum of propodeum macropunctate. Gastral tergites densely superficially punctate and shiny.

Dorsa of head and mesosoma with dense, short standing hairs. Median point of anterior clypeal margin with a long hair. Antennal scape with dense standing hairs (most of them shorter than the maximum width of antennal scape); antennal segments II–XII with short standing hairs. Petiole with sparse appressed hairs; petiolar spines without hairs; sternite with sparse standing hairs. Gaster with dense pubescence mixed with sparse short hairs that are shorter than those on head. Legs with sparse short hairs. Body entirely black; legs reddish brown. Gaster in some specimens from colonies WJT04-S31 and KK14-Pol-06 reddish brown.

Description of queen ( Figs 1 D–F , 2 A–F )

Similar to the worker in structure, sculpture, pilosity, and coloration, with the following conditions that should be noted: body slightly larger; head in full-face view oval, clearly longer than broad with posterior margin roundly convex; eye large, located close to posterolateral corner of head; median ocellus located at level of posterior margin of eye and slightly larger than lateral ocellus; in dorsal view, pronotum short, its anterior margin distinctly convex and posterior margin distinctly concave; mesoscutum trapezoidal; parapsidal line distinct and long; scutellum trapezoidal, almost as long as broad; metanotum short; metanotopropodeal sulcus deep; propodeum in profile view with almost straight dorsal outline; propodeal junction bluntly angular; petiolar spine short comparing with petiolar node; body hairs relatively denser and longer than in the worker.

Habitat. Carton nests of P. constructor were found on the underside of plant leaves or between leaves. They were located c.a. 1.59–2.80 m above ground on shrubs. The nest was around 1.74–10.53 cm long, 1.51–5.66 cm wide, and 0.22–0.95 cm deep, with only one nest entrance.

Polyrhachis constructor is distinctly allopatric with P. longipilosa in distribution, occurring in Sundaland (southern Thailand and Borneo) and southernmost part of Indochina subregions (Prachuap Khirikhan Province). On the other hand, P. longipilosa is recorded from western part of Thailand (Kanchanaburi Province).

Distribution. Thailand, Malaysia, Singapore, and Indonesia ( Fig. 10 A ).

Remarks. Polyrhachis constructor is most similar to P. longipilosa sp. nov. in having hairs on dorsa of head, mesosoma and gaster and on antennal scape. However, P. constructor has the shorter hairs and weaker sculpturing than in the latter (see figures 1 A–C and 6 for comparison). See ‘Remarks’ under P. longipilosa . The syntype alate queen of P. constructor quite similar to the syntype alate queen of P. piliventris . Only minor differential characteristics or just variation have been seen: 1) head is slightly longer (CI 73 in P. constructor ; CI 85 in P. piliventris ); 2) posterior margin of head stronger convex than in P. piliventris ; 3) anterior margin of mesoscutum weaker convex than in P. piliventris . The syntype workers of P. elii are most similar to workers of P. constructor in most aspects but the body size is slightly larger and slightly denser hairs. However, we did not find any major characteristics to distinguish P. constructor ( Figs. 1 A–C , 2 A–C ) from the syntypes of P. piliventris ( Fig. 2 D–F ) and P. elii ( Fig. 3 A–C ). Thus, we here synonymize P. piliventris and P. elii with P. constructor .

Figures

FIGURE 1. Polyrhachis constructor. A–C, Non-type worker (NN220308-01); D–F, non-type alate queen (NN220308-02); A, D, body in profile view; B, E, body in dorsal view; C, F, head in full-face view.

FIGURE 2. Polyrhachis constructor.A–C, Syntype of Polyrhachis constructor (alate queen ANTWEB CASENT0901846); D– F, syntype of Polyrhachis piliventris (alate queen); A, D (ANTWEB CASENT0903307), body in profile view; B, E (ANTWEB CASENT0903307), body in dorsal view; C, F, head in full-face view.

FIGURE 3. Syntype of Polyrhachis elii (worker, ANTWEB CASENT0905566); A, Body in profile view; B, head in full-face view; C, body in dorsal view.

FIGURE 10. Distribution map of Polyrhachis flavicornis species group. A) P. constructor and P. longipilosa sp. nov. B) P. flavicornis and P. varicolor.