Polyrhachis pilbara

This species appears restricted to the mulga and spinifex clad hills of the Pilbara region of north-western Western Australia. Nothing is known about its biology or nesting habits.

Identification
A member of the penelope species-group in the Polyrhachis subgenus Hagiomyrma. Rather coarsely reticulate-punctate sculpturation and the bristle-like hairs along the antennal scapes, make P. pilbara a very characteristic representative of the pilbara-complex within the penelope-group.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Castes
Known only from the worker caste.

Nomenclature

 *  pilbara. Polyrhachis (Hagiomyrma) pilbara Kohout, 2013: 542, figs. 8C-D (w.) AUSTRALIA.

Worker
(holotype cited first): TL c. 7.76, 6.85-8.16; HL 1.87, 1.65- 1.90; HW 1.47, 1.34-1.50; CI 79, 76-81; SL 2.28, 2.06-2.34; SI 155, 150-159; PW 1.37, 1.28-1.43; MW 0.81, 0.73-0.87; PMI 169, 164-175; MTL 2.40, 2.09-2.50 (11 measured).

Anterior clypeal margin with shallow, denticulate flange, flanked laterally by acute teeth. Clypeus with median carina; virtually straight in profile, posteriorly rounding into shallow basal margin. Frontal triangle poorly indicated. Frontal carinae sinuate with only weakly raised margins. Sides of head converging towards mandibular bases in almost straight line; behind eyes, sides rounding into convex occipital margin. Eyes only moderately convex; in full face view not or only marginally exceeding lateral cephalic outline. Ocelli lacking. Pronotal humeri rounded with weakly raised margins; pronotum widest at mid-length. Promesonotal suture distinctly impressed. Lateral margins of mesonotum converging towards indistinct metanotal groove. Propodeal margins terminating in weakly divergent spines; spines horizontal from bases and weakly curving downwards at midlength. Petiole rather broad at base in lateral view; dorsum weakly concave medially, armed with divergent spines elevated from bases, tips upturned. Anterior face of first gastral tergite distinctly higher than full height of petiole, widely rounding onto dorsum.

Mandibles longitudinally striate with piliferous pits. Head, mesosoma and petiole reticulate-punctate, sculpturation mostly longitudinal on vertex and dorsum of mesosoma. Spines distinctly sculptured for most of length, only tips smooth and polished. Gaster closely reticulate-punctate.

Mandibular masticatory and outer borders with numerous, curved, golden hairs. Anterior clypeal margin with several anteriorly projecting longer setae medially and a few short setae fringing margin laterally. Numerous, medium length, erect, golden hairs on most body surfaces, including appendages; antennal scapes, sides of head in full face view and pronotal humeri in dorsal view distinctly fringed with short bristle-like hairs. Gaster with hairs somewhat longer and posteriorly directed, notably around apex and on venter. Dorsum of gaster with closely appressed, golden pubescence, completely hiding underlying sculpturation; pubescence much diluted on gastral venter.

Black; mandibles, appendages, including coxae and gaster medium reddish-brown.

Type Material


Type deposition: Holotype and 2 paratypes in ; 2 paratypes each in, , and.

Etymology
After the type locality, the Pilbara region in the north-west of Western Australia.

References based on Global Ant Biodiversity Informatics

 * Kohout R.J. 2013. Revision of Polyrhachis (Hagiomyrma) Wheeler, 1911 (Insecta: Hymenoptera: Formicidae: Formicinae). Memoirs of the Queensland Museum  Nature 56: 487577