Polyrhachis inusitata

Identification
Polyrhachis inusitata is closely related to Polyrhachis sericeopubescens with which it was erroneously synonymised by Kohout (1998). However, P. inusitata differs from P. sericeopubescens by its smaller size and the form of the sculpturation on the sides of the mesosoma which is reticulate‑rugose in the former and distinctly longitudinally striate in P. sericeopubescens. The lateral petiolar teeth in P. inusitata are reduced to more-or-less distinct denticles, while they are produced into distinct short teeth in P. sericeopubescens. The gastral pilosity in P. inusitata is shorter and more abundant, while it is markedly longer but more sparse in P. sericeopubescens. Polyrhachis inusitata is also similar to Polyrhachis continua Emery, 1887, however it differs from that species by its distinctly slender body, reticulate-rugose sculpturation and the abundant short hairs distributed over most of the body. In contrast, the body in P. continua is wider and relatively robust, the sculpturation on head and mesosoma more-or-less regularly longitudinally striate and the hairs distinctly longer and much diluted.

Distribution
P. inusitata is apparently limited to the mid Cape York Peninsula, from the Claudie River basin at Iron Range to the McIlwraith Range (Kohout 1989)

This taxon was described from Australia.

Castes
Sexuals and immature stages unknown.

Nomenclature

 *  inusitata. Polyrhachis inusitata Kohout, 1989: 513, figs. 4, 5, 9 (w.) AUSTRALIA. Junior synonym of sericeopubescens: Kohout, 1998: 520. Revived from synonymy: Kohout, 2012: 39.

Holotype and paratype workers from West Claudie R., Iron Range area, Cape York Peninsula, 12°44’S, 143°14’E, Queensland, Australia, 3-10.xii.1985, G.B. Monteith & D. Cook (examined by Kohout, 2012).

Worker
Dimensions (holotype cited first): TL 10.53, 9.38-9.82; HL 2.56, 2.31-2.37; HW 1.87, 1.72-1.75; CI 73, 74; SL 3.53, 3.30-3.48; SI 189, 192-199; PW 1.61, 1.36-1.51; MTL 3.56, 3.38-3.58 (3 measured).

Mandibles with 5 teeth. Clypeus almost straight in profile, anterior margin obtusely truncated medially. Head in front of eyes converging anteriorly, its lateral margins shallowly concave. Behind the eyes the head is markedly wider, with the sides forming a blunt continuous ridge extending on each side toward the posterior angle, where it meets a similar ridge which commences on each side at the base of mandible and separates the gena from the ventral parts of the head. Eyes large, convex, situated well back giving the face a somewhat elongated appearance; in full face view the eyes clearly break the outline of the head. Frontal carinae with strongly raised lobes. Pronotal dorsum armed with a pair of relatively short, downturned, dorsally flattened spines; their lateral borders continuous with the posteriorly converging pronotal margins. Mesonotal dorsum narrower than pronotal, feebly transversely convex. Propodeum with anterior angles somewhat upturned, sides weakly margined and only slightly q)Dverging posteriorly, terminating in ill-defined angles. Petiolar dorsum armed with a pair of relatively long, slender, subparallel spines; the lateral teeth reduced to more or less distinct denticles. Base of first gastral tergite shallowly truncated.

Mandibles finely longitudinally striate, with numerous piliferous pits. Clypeus and front of head mostly finely irregularly rugose; sculptural intensity decreasing laterally, with sides of head finely reticulate, and increasing dorsally, with occiput more or less rugose. Dorsum and sides of meso soma reticulate-punctate. Petiole and gaster finely shagreened.

Relatively short, semierect, yellowish to brown hairs abundant on dorsum of head and mesosoma, and diluted elsewhere, particularly on the petiole, which has only a few very short hairs scattered along its lateral edge and on the spines. The hairs are relatively long on the gaster, where they are somewhat posteriorly directed. Very short, golden, appressed pubescence very dilute all over the body, except the gaster, where it is more abundant, with a distinct reddish tint on the dorsal aspect.

Black, with mandibles at the masticatory border and appendages infuscated reddish-brown.

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.