Polyrhachis injinooi

All known specimens of P. injinooi were collected foraging on the ground in open forest and savannah woodland, together with specimens of Polyrhachis schenckii. Both species have similar nesting habits, building nests in the ground with the entrances hidden under pieces of wood or stones. However, the distribution of P. injinooi is much more restricted than that of P. schenckii, with the species known only from Cape York Peninsula as far south as Cooktown.

Identification
A member of the schenckii species-group in the Polyrhachis subgenus Hagiomyrma. Kohout (2013) - Polyrhachis injinooi is very similar to Polyrhachis schenckii and in addition to their virtually identical colour patterns, they both have a strongly posteriorly narrowed pro-mesonotal dorsum (PMI 190-209 in P. injinooi and 210-250 in P. schenckii). However, Polyrhachis injinooi is generally larger (HL 1.53-1.75 versus 1.31-1.56 in P. schenckii) and has somewhat flattened antennal scapes, distinctly longer body hairs and very sparse, closely appressed pubescence on the dorsum of gaster. In contrast, P. schenckii has antennal scapes that are virtually circular in cross section, distinctly shorter, bristlelike hairs and silvery or golden, appressed pubescence on the gastral dorsum. The eyes are also distinctly smaller in P. inginooi than in P. schenckii.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Castes
Sexuals and immature stages unknown.

Nomenclature

 *  injinooi. Polyrhachis (Hagiomyrma) injinooi Kohout, 2013: 556, figs. 11E-F (w.) AUSTRALIA.

Worker
(holotype cited first): TL c. 7.11, 5.74-7.16; HL 1.75, 1.53- 1.75; HW 1.36, 1.15-1.36; CI 78, 75-85; SL 1.87, 1.65-1.87; SI 137, 134-143; PW 1.17, 0.97-1.20; MW 0.56, 0.50-0.59; PMI 209, 190-209; MTL 2.25, 1.87-2.25 (15 measured).

Anterior clypeal margin with median denticulate flange, flanked by acute angles. Clypeus with distinctly raised median carina; virtually straight in profile (medially shallowly concave in some specimens), narrowly rounding into moderately impressed basal margin. Frontal triangle poorly indicated. Frontal carinae sinuate with weakly raised margins; central area flat with frontal furrow replaced anteriorly by distinct carina. Sides of head in front of eyes converging towards mandibular bases in virtually straight line; behind eyes, sides widely rounding into convex occipital margin. Eyes convex, in full face view marginally breaking lateral cephalic outline. Ocelli lacking; position of median ocellus indicated by shallow pit in cephalic sculpture. Antennal scapes distinctly flattened dorsally for most of length. Pronotal humeri narrowly rounded with indication of blunt angles in some specimens. Lateral margins of promesonotal dorsum narrowly raised, strongly converging posteriorly (PMI 190-209). Metanotal groove poorly defined medially. Propodeal dorsum with lateral margins divergent, terminating in weakly sinuate, acute spines. Anterior face of petiole straight, posterior face descending towards base in oblique, straight line; dorsum concave medially, laterally rounding into horizontal, divergent, acute spines, with tips weakly curved outwards.

Head and mesosoma finely reticulate-punctate, with interspaces between reticulae, notably on dorsum of mesosoma, rather smooth and polished; spines, petiole and gaster very smooth, highly polished.

Mandibles with masticatory and outer borders with curved, rather short, golden hairs. Anterior clypeal margin with a few longer setae medially and fringe of short setae lining margin laterally. Antennal scapes and legs with numerous short, bristle-like hairs. Head, mesosoma, petiole and gaster with relatively long, mostly erect or suberect hairs, longest hairs more than half greatest diameter of eyes. Pubescence absent from most body surfaces, except for patches of short, closely appressed hairs on fore coxae, propodeal declivity and posterior face of petiole. Gaster with more abundant, somewhat longer, appressed pubescence on venter, very sparse on dorsum.

Reddish-brown to rusty-red. Mandibles, anterior clypeal margin, frontal carinae, occipital margin, lateral margins of mesosoma and outer borders of spines narowly lined with black. Gaster and tarsi a shade darker.

Etymology
After the Injinoo Aboriginal Community, the traditional owners of the land on which the type locality of P. injinooi is located.

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