Polyrhachis paxilla

Kohout 2013): This species is apparently a lignicolous species with a single nest collected from a dry, hollow bamboo internode. The nest was located on the edge of a small patch of lowland rainforest within swampy grassland in Papua New Guinea, a similar habitat to that on Cape York Peninsula where the Australian specimens of P. paxilla were collected. They were found foraging together with Polyrhachis bamaga Kohout, a species of similar appearance and almost identical body sculpturation that belongs to the recently erected subgenus Hirtomyrma Kohout.

Identification
A member of the schenkii species-group in the Polyrhachis subgenus Hagiomyrma. With its characteristic, vermiculate-rugose sculpturation, P. paxilla is easily recognised. It bears some similarity to Polyrhachis lachesis and Forel (1897) redescibed it as P. lachesis maeandrifera.

Distribution based on Regional Taxon Lists
Australasian Region: Australia. Indo-Australian Region: Indonesia, New Guinea.

Castes
Male unknown; single pupa in QM spirit collection.

Nomenclature

 *  paxilla. Polyrhachis paxillus Smith, F. 1863: 17 (w.) INDONESIA (Martabello I.). Combination in P. (Chariomyrma): Emery, 1925b: 188; in P. (Hagiomyrma): Kohout, 1988c: 435. Senior synonym of maeandrifera: Kohout, 1988c: 435.
 * maeandrifera. Polyrhachis lachesis subsp. maeandrifera Emery, 1897d: 582 (w.) NEW GUINEA. Junior synonym of paxilla: Kohout, 1988c: 435.

Worker
Kohout (2013) - (holotype cited first): TL c. 8.92, 7.36-8.92; HL 2.17, 1.90-2.17; HW 1.66, 1.47-1.66; CI 76, 75-79; SL 2.47, 2.12-2.47; SI 149, 141-149; PW 1.54, 1.31-1.54; MW 0.86, 0.78-0.86; PMI 179, 159-180; MTL 3.02, 2.50-3.02 (10 measured).

Anterior clypeal margin with obtusely denticulate median flange. Clypeus with median carina distinctly raised towards basal margin; strongly sinuate in profile. Frontal triangle distinct. Frontal carinae sinuate with margins distinctly raised at midlength. Sides of head in front of eyes converging towards mandibular bases in weakly convex line; behind eyes, sides widely rounding into convex occipital margin. Eyes moderately convex, in full face view only marginally breaking lateral cephalic outline. Ocelli lacking. Pronotal dorsum with raised lateral margins; pronotal humeri distinctly dilated, forming rounded or bluntly angular, laminate prominences. Mesonotum with posteriorly converging lateral margins; metanotal groove indistinct medially. Propodeal dorsum with margins subparallel, terminating in slender, acute spines, obliquely elevated from bases, sinuate at midlength, tips curved outwards. Petiole with anterior face terminating dorsally in jagged, transverse ridge, merging laterally into slender, acute, divergent spines with bases situated well below apex of dorsal convexity.

Mandibles longitudinally striate with piliferous pits. Clypeus finely punctate. Dorsa of head, mesosoma and petiole with characteristic vermiculate-rugose sculpturation; sides of mesosoma more finely reticulate. Gaster finely shagreened.

Mandibles with numerous golden, curved hairs at masticatory borders and shorter appressed hairs towards mandibular bases. All body surfaces, including outline of head and appendages, with numerous bristle-like, mostly erect hairs, shorter than maximum diameter of eyes. Hairs dark brown to black on dorsum, golden to golden-brown and generally shorter on ventral surfaces. Silvery, appressed pubescence in various densities over most body parts, denser with distinct rusty tint on gastral dorsum.

Black or very dark reddish-brown; mandibles, clypeus, antennae and spines medium to dark reddish-brown. Legs, including coxae distinctly lighter, medium reddish-brown. Apex and venter of gaster blotched reddish-brown.

Queen
Kohout (2013) - TL c. 8.77; HL 2.03; HW 1.47; CI 72; SL 2.28; SI 155; PW 1.78; MTL 2.81 (1 measured). Apart from sexual characters very similar to worker, except: sides of head converging towards mandibular bases in straight line; eyes distinctly more convex, in full face view clearly exceeding lateral cephalic outline. Humeral angles of pronotum with narrowly rounded and weakly raised margins; mesoscutum distinctly wider than long with anterior margin widely rounded; median line distinct, parapsides flat. Anterior margin of mesoscutum in profile widely rounding onto virtually flat dorsum; mesoscutellum marginally elevated above dorsal plane of mesoscutum, weakly convex. Propodeal and petiolar spines shorter than in worker. Sculpturation, pilosity, pubescence and colour identical to worker.

Type Material


Polyrhachis paxillus

Holotype worker in. Labelled “Mat” (= Martabello I.) and with a Donisthorpe type-label.