Polyrhachis elegantula

This is a relatively common species throughout lowland open eucalypt forests, Melaleuca dominanted coastal plains and savannah woodlands. Its distribution extends from Cape York (Somerset, Bamaga), south to about Ingham.

Identification
A member of the ammon species-group in the Polyrhachis subgenus Hagiomyrma. Kohout (2013) - Polyrhachis elegantula is somewhat similar to several Hagiomyrma species, but not to any of them in particular. It is characterised by its exceptionally tidy appearance, rather slender body and the lightly diffused reddish patch on the gastral dorsum.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Castes
Known only from the worker caste.

Nomenclature

 *  elegantula. Polyrhachis (Hagiomyrma) elegantula Kohout, 2013: 519, figs. 3G-H (w.) AUSTRALIA.

Worker
(holotype cited first) TL c. 8.16, 7.51-8.72; HL 2.03, 1.84- 2.15; HW 1.62, 1.47-1.68; CI 80, 78-81; SL 2.59, 2.34-2.73; SI 160, 155-162; PW 1.43, 1.31-1.56; MW 0.94, 0.84-1.03; PMI 152, 140-167; MTL 2.87, 2.59-3.06 (19 measured).

Anterior clypeal margin with obtusely denticulate median flange. Clypeus with median carina, sinuate in profile, with moderately impressed basal margin. Frontal furrow poorly indicated. Frontal carinae sinuate with weakly raised margins; central area with rather flat frontal furrow. Sides of head in front of eyes almost straight towards mandibular bases; behind eyes, sides rounding into convex occipital margin. Eyes moderately convex, in full face view reaching or marginally exceeding lateral cephalic outline. Ocelli lacking. Pronotal humeri rounded with raised lateral margins, dorsally shallowly concave; pronotal dorsum with lateral margins behind humeri emarginate or notched, weakly converging towards promesonotal suture. Lateral margins of mesonotum converging posteriorly and weakly raised towards medially flat metanotal groove. Propodeal dorsum with margins terminating in slender, horizontal, subparallel, acute spines. Anterior face of petiole in side view rounding dorsally into long, slender, elevated, weakly divergent spines with tips curved upwards. Anterior face of first gastral tergite widely rounding onto dosum.

Mandibles densely and closely longitudinally striate with numerous piliferous pits. Head, mesosoma and petiole very finely reticulate-punctate. Tips of spines smooth and polished. Gaster shagreened.

Mandibles at masticatory and outer borders with numerous, curved, golden hairs. Anterior clypeal margin with a few, anteriorly directed setae and several short setae fringing margin laterally. Numerous relatively short, erect, golden hairs on dorsum of head, mesosoma and petiole, with several hairs on coxae and venter of femora. Gaster with numerous, erect, posteriorly inclined hairs dorsally; somewhat longer hairs around apex and on venter of gaster. Closely appressed, somewhat medially radiating, golden pubescence with somewhat reddish hue, rather abundant on dorsum of head and mesosoma, completely hiding underlying sculpturation; pubescence distinctly more pale golden or silvery along lateral margins and sides of mesosoma, on propodeal dorsum, bases of spines and gaster. Dorsum of gaster with very fine, closely appressed, golden pubescence and distinct, reddish, laterally diffused, median patch; pubescence more silvery on sides and venter of gaster.

Black, with mandibular teeth very dark reddish-brown.

Etymology
Derived from the Latin word elegantulus, meaning fine, graceful, in reference to the species somewhat elegant appearance, given by the very tidy, closely appressed pubescence.

Determination Clarifications
Polyrhachis elegantula was listed earlier by Kohout (2000: 199) as ‘Hagio 10’.

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