Polyrhachis andromache

In Australia, P. andromache is restricted to the lowland rainforests of Cape York Peninsula north of the 14° parallel where it is relatively common. It is characterised by its abundant, distinctly golden or silvery pubescence and yellow or orange-coloured appendages. Polyrhachis andromache builds nests of silk and vegetation debris in various tree cavities, but also within the hollow internodes of standing bamboo (Kohout 1988b, 1989, 1999; Robson & Kohout 2007) (from Kohout, 2012).

Identification
Kohout (1988) - Polyrhachis ithona is easily separable in having numerous short hairs projecting from the sides of the head behind the eyes. Such hairs are never present in P. andromache. The head of P. ithona is much broader behind than in front and the antennal scapes relatively short (SI < 140) compared to those of P. andromache (SI > 145). P. andromache is also more slender and delicate than ithona, which is a relatively large and stoutly built species.

Distribution
The known distribution is from Moluccas to New Guinea and northern Australia, where the species has been recorded from Torres Strait Islands and Cape York Peninsula as far south as Iron Range. (Kohout 1989)

Castes
Males and immature stages are present in the ANIC and RJK spirit collections.

Nomenclature

 * hector. Polyrhachis hector Smith, F. 1859a: 142 (w.) INDONESIA (Aru I.). [Junior primary homonym of hector Smith, above.] Replacement name: andromache Roger, 1863b: 8.
 * chaonia. Polyrhachis chaonia Smith, F. 1861b: 42, pl. 1, fig. 18 (q.) INDONESIA (Halmahera I.). Combination in P. (Myrma): Emery, 1925b: 200. Junior synonym of ithona: Bolton, 1974b: 177; of andromache: Dorow, 1995: 31.
 *  andromache. Polyrhachis andromache Roger, 1863b: 8. Replacement name for hector Smith, F. 1859a: 142. [Junior primary homonym of hector Smith, F. 1857a: 62.] Donisthorpe, 1949g: 420 (m.); Kohout, 1989: 510 (w.q.). Combination in P. (Myrma): Forel, 1915b: 110. Subspecies of relucens: Emery, 1897d: 579; Forel, 1901b: 28. Senior synonym of connectens: Emery, 1897d: 580. Junior synonym of ithona: Bolton, 1974b: 177. Revived from synonymy, revived status as species and senior synonym of australiae: Kohout, 1988c: 430. Senior synonym of semirufipes and material of the unavailable name harmsi referred here: Kohout, 1998: 521.
 * australiae. Polyrhachis connectens var. australiae Emery, 1887a: 231 (w.) AUSTRALIA. Combination in P. (Myrma): Emery, 1925b: 202. Junior synonym of relucens: Emery, 1893e: 228; of andromache: Emery, 1896d: 379. Revived from synonymy as subspecies of relucens: Taylor & Brown, D.R. 1985: 140. Junior synonym of andromache: Kohout, 1988c: 431.
 * connectens. Polyrhachis connectens Emery, 1887a: 230, pl. 4, fig. 19 (w.) NEW GUINEA. Subspecies of relucens: Dalla Torre, 1893: 267; Emery, 1896d: 379. Junior synonym of andromache: Emery, 1897d: 580.
 * semirufipes. Polyrhachis (Myrma) proxima var. semirufipes Donisthorpe, 1943d: 469 (w.) NEW GUINEA. Junior synonym of andromache: Kohout, 1998: 521.

Polyrhachis hector type material.

Holotype worker from Aru Island, Indonesia (A.R.Wallace) (examined by Kohout, 2012).

Polyrhachis connectens australiae type material.

Syntype workers and queen from Somerset, Cape York, Australia (L.M. D’Albertis) (examined by Kohout, 2012).

Type Material


Polyrhachis chaonia

Holotype queen in. Labelled “Gil.” (= Gilolo (Halmahera)) and with a Donisthorpe type-label.

Polyrhachis hector

Holotype worker in. Labelled “Aroo” (= Aru I., New Guinea) and with a Donisthorpe type-label. Below this is a Donisthorpe det. label “relucens subsp. andromache.”

Worker
Kohout (1989) - Dimensions: TL 7.58-9.73; HL 2.12-2.50; HW 1.65-2.01; CI 78-82; SL 2.56-2.97; SI 145-158; PW l.18-1.51; MTL 2.59-3.07 (30 measured).

Mandibles with 5 teeth. Clypeus in profile almost straight; the anterior margin entire. Sides of head in front of eyes shallowly concave, slightly converging anteriorly; widely rounded behind. Eyes convex, in full face view usually only marginally breaking the outline of the head. Frontal carinae sharply raised. Pronotal dorsum with a pair of long, divergent, somewhat flattened spines; their dorsolateral borders continuous with the pronotal margins. Mesonotal dorsum transversely convex. wider than pronotum at the base, the lateral margins converging strongly posteriorly. Propodeal dorsum almost flat, with margins converging into weakly upturned posterior angles. Petiole with two posterodorsally directed spines and, between them, a more or less distinct, small intercalary tooth. A somewhat flattened, deeply emarginated tooth, is situated laterally below the level of the base of each spine. First gastral tergite shallowly concave basally.

Mandibles finely, regularly striate, with numerous piliferous pits. Head and lateral branches of mesosoma finely reticulate; dorsum of mesosoma, petiole and the gaster shagreened.

A few long, erect, somewhat undulated hairs scattered on dorsum of the head and mesosoma. Such hairs are relatively more abundant and posteriorly directed on the gaster. Bright golden or, less frequently, silvery pubescence more or less obscuring the underlying sculpturation. And abundant all over the body, except on the mandibles and tips of the spines.

Generally black, with coxae, femora, tibia and proximal and distal ends of the antennal scapes yellow or light yellowish-brown.

Queen
Kohout (1989) - Dimensions: TL 9.98-11.59; HL 2.50-2.74; HW 2.01-2.21; CI 79-82; SL 2.87-3.12; SI 136-143; PW 2.03-2.22; MTL 3.06-3.22 (7 measured).

Female almost identical to worker apart from its larger size and the characters identifying full sexuality. The pronotal spines are shorter and downturned, and the dorsum of petiole armed with 3 distinct teeth.

Additional References

 * Kohout, R.J. 2012. A review of the Australian Polyrhachis ants of the subgenera Myrma Billberg, Myrmatopa Forel, Myrmothrinax Forel and Polyrhachis Fr. Smith (Hymenoptera: Formicidae: Formicinae). Memoirs of the Queensland Museum – Nature 56(1): 25-59.