Polyrhachis constructor

In Thailand, 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 (Jaitrong et al., 2023).

Identification
Polyrhachis constructor is most similar to Polyrhachis longipilosa 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) (Jaitrong et al., 2023).

Distribution
Polyrhachis constructor is distinctly allopatric with Polyrhachis 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) (Jaitrong et al., 2023).

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia, Singapore.

Nomenclature

 *  constructor. Polyrhachis constructor Smith, F. 1857a: 60 (q.) BORNEO. Combination in P. (Myrmatopa): Donisthorpe, 1932c: 445. Unplaced to subgenus: Dorow, 1995: 65, but Donisthorpe probably correct. [P. constructrix: Schulz, 1906: 156; unjustified emendation.]
 * elii. Polyrhachis elii Emery, 1900d: 711 (w.) INDONESIA (Mentawei I.).
 * Combination in P. (Myrmatopa): Emery, 1925b: 180.
 * Junior synonym of constructor: Jaitrong et al., 2023: 448.
 * piliventris. Polyrhachis piliventris Smith, F. 1858b: 60, pl. 4, fig. 24 (q.) SINGAPORE.
 * Combination in P. (Myrmatopa): Dorow, 1995: 44; Bolton, 1995b: 354.
 * Junior synonym of constructor: Jaitrong et al., 2023: 448.

Type Material
Type material examined by Jaitrong et al. (2023):
 * The syntype alate queen of Polyrhachis constructor from East Malaysia, Borneo, Sarawak (A.R. Wallace), deposited in OXUM.
 * Two syntype workers of Polyrhachis elii from Indonesia, Mentawai Island, Sipora, Sereinu, V–VI.1894 (E. Modigliani), deposited in MCSN.
 * The syntype alate queen of Polyrhachis piliventris from Singapore (A.R. Wallace), deposited in BMNH.

Holotype alate queen in. Labelled “SAR.” (= Sarawak) and with a Donisthorpe type-label.

Taxonomic Notes
The syntype alate queen of P. constructor is 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.

References based on Global Ant Biodiversity Informatics

 * Chapman, J. W., and Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327
 * Emery, C. "Formiche raccolte da Elio Modigliani in Sumatra, Engano e Mentawei." Annali del Museo Civico di Storia Naturale Giacomo Doria (Genova) (2) 20, no. 40 (1900): 661-722.
 * Kohout R.J., and M. Mohamed. 2008. A preliminary list of the Polyrhachis ants of the Maliau Basin Conservation area in Sabah, Borneo (Hymenoptera: Formicidae: Formicinae). Asian Myrmecology 2: 63-70.
 * Pfeiffer M.; Mezger, D.; Hosoishi, S.; Bakhtiar, E. Y.; Kohout, R. J. 2011. The Formicidae of Borneo (Insecta: Hymenoptera): a preliminary species list. Asian Myrmecology 4:9-58
 * Robson Simon Database Polyrhachis -05 Sept 2014