Polyrhachis neuguinensis

The type series specimens of this species were collected from a nest in a tree crevice in swampy lowland rainforest.

Identification
A member of the Polyrhachis continua species group in the subgenus Myrma

Polyrhachis neuguinensis is an easily recognised species featuring a rather slender mesosomal dorsum with distinctly upturned lateral margins and relatively long pronotal spines. It also features acute, distinctly upturned, propodeal teeth and a transverse carina that completely divides the propodeal dorsum from the declivity. (Kohout 2013)

Distribution based on Regional Taxon Lists
Indo-Australian Region: New Guinea.

Castes
Male and immature stages unknown.

Nomenclature

 *  neuguinensis. Polyrhachis neuguinensis Kohout, 2013: 30, figs. 19, 24-25 (w.q.) PAPUA NEW GUINEA.

Worker
Dimensions (holotype cited first): TL c. 10.43, 9.37-10.43; HL 2.56, 2.34-2.56; HW 2.00, 1,78-2.00; CI 78, 76-80; SL 3.33, 3.02-3.33; SI 166, 162-172; PW 1.68, 1.50-1.68; MTL 3.53, 3.22-3.53 (11 measured).

Anterior clypeal margin arcuate, medially obtusely truncate and shallowly emarginate. Clypeus with posteriorly raised median carina; clypeus in profile straight with shallow depression behind anterior margin, posteriorly rounding into shallow basal margin. Frontal triangle distinctly impressed. Frontal carinae with highly raised, laminate margins; central area narrow with indistinct frontal furrow. Sides of head in front of eyes virtually straight, weakly converging anteriorly; behind eyes sides produced into blunt carina extending towards rather prominent occipital corners. Eyes convex, moderately posteriorly protracted, in full face view exceeding lateral cephalic outline. Ocelli lacking. Pronotal dorsum with long, slender, acute spines directed anterolaterally and curved slightly downwards, lateral edges of spines acute and continuous with weakly upturned pronotal margins. Promesonotal suture distinctly impressed laterally; mesonotal dorsum transverse with strongly raised, laminate, lateral margins converging into medially flat, posteriorly bowed, metanotal groove. Propodeal dorsum with lateral margins strongly raised anteriorly, virtually flat posteriorly and terminating in distinct, acute teeth with inner borders continuous medially for short distance and terminating in blunt, transverse carina that somewhat divides propodeal dorsum from declivity. Petiole scale-like, with dorsal margin armed with two slender, posteriorly curved, acute spines with inner margins forming ‘U’-shaped petiolar dorsum; lateral margins of petiole below base of each spine with short, distinct, acute tooth. Anterior face of first gastral segment flat, anterodorsal margin widely rounding onto dorsum.

Mandibles distinctly, longitudinally striate. Clypeus reticulate-punctate; rest of head and mesosoma, including sides, distinctly, mostly longitudinally striate; propodeal declivity and petiole, including spines, finely reticulate. Gaster finely shagreened.

Mandibular masticatory borders and outer margins with numerous, semierect, golden hairs. Anterior clypeal margin with several long, anteriorly directed setae medially and fringe of shorter setae laterally. Numerous short to medium length, erect to semierect hairs on clypeus, along frontal carinae and vertex, many hairs fringing lateral cephalic outline in full face view. Antennal scapes with numerous, semierect, short to medium length hairs along leading edge and several hairs along inferior edge. Mesosoma, except declivity, and legs, except dorsal surfaces of femora, with numerous short to medium length, erect hairs; petiole with numerous shorter hairs along lateral margins, including inner margins of spines. Gaster with numerous medium length, posteriorly inclined hairs, distinctly increasing in length towards gastral apex and over venter. Closely appressed, silvery white or greyish pubescence variously distributed over most body surfaces, somewhat shorter with distinctly reddish tint on gastral dorsum.

Colour. Black; mandibular masticatory borders lined reddish brown; antennae with funicular segments progressively lighter, yellowish brown, towards apices. Legs, including mid and hind coxae, medium reddish brown; front coxae and tarsi a shade darker. Gaster reddish brown.

Queen
Dimensions: TL c. 11.69; HL 2.62; HW 2.09; CI 80; SL 3.28; SI 157; PW 2.34; MTL 3.53 (1 measured).

Queen larger than worker with usual characters identifying full sexuality, including three ocelli, complete thoracic structure and wings. Pronotal spines distinctly shorter, broad-based. Mesoscutum only marginally wider than long; lateral margins strongly converging anteriorly into narrowly rounded anterior margin; median line distinct; parapsides virtually flat; mesoscutum in profile with relatively low, widely rounded anterior face and only slightly convex dorsum. Mesoscutellum only weakly convex, not distinctly elevated above dorsal plane of mesosoma. Propodeum convex in outline with lateral margins terminating in medially directed, short ridges; propodeal dorsum descending into weakly concave declivity in medially uninterrupted line. Petiole with dorsal spines distinctly shorter and dorsum between with minute intercalary denticle. Sculpturation, pilosity, pubescence and colour scheme very similar to worker.

Etymology
Named after the island of New Guinea.

References based on Global Ant Biodiversity Informatics

 * Kohout R. J. 2013. A review of the Polyrhachis continua species-group of the subgenus Myrma Billberg (Hymenoptera: Formicidae: Formicinae) with keys and descriptions of new species. Australian Entomologist 40(1): 13-46.