Polyrhachis planata

Known only from the holotype.

Identification
Kohout (2007) - In general appearance and color, P. planata is similar to Polyrhachis pallipes. However, it differs from that and other Aulacomyrma species by its virtually flat pronotal dorsum and distinctly transverse petiolar node with its lateral spines strongly bent backwards.

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

Castes
Known only from the worker caste.

Nomenclature

 *  planata. Polyrhachis (Aulacomyrma) planata Kohout, 2007a: 205, figs. 21, 24, 27 (w.) NEW GUINEA.

Worker
Holotype: TL c. 4.59; HL 1.25; HW 1.08; CI 86; SL 1.31; SI 121; PW 1.00; MTL 1.18.

Clypeus with anterior margin arcuate, entire. Sides of head weakly convex and gently converging in front of eyes towards bases of mandibles. Eyes convex, clearly breaking cephalic outline in full face view. Mesosomal dorsum distinctly marginate along entire length, pronotal and mesonotal margins converging posteriorly. Pronotal dorsum rather flat; humeri armed with broad-based, blunt teeth. Propodeal margins divergent, terminating posteriorly in blunt processes, that appear as minute teeth in profile and form short, transverse, medially unconnected ridges, so that propodeal dorsum descends into concave declivity in medially uninterrupted curve. Petiole strongly transverse, dorsal margin entire; lateral spines very distinct, strongly curved backwards and upwards. Anterior face of first gastral segment concave medially; anterodorsal border of concavity sharply margined, but not distinctly raised above dorsal surface of segment.

Mandibles very finely longitudinally striate. Head and dorsum of mesosoma more-or-less regularly striate; striae mostly longitudinal on head and dorsum of mesosoma, anteriorly converging on clypeus and oblique on sides of mesosoma. First gastral segment shagreened dorsally, longitudinally striate laterally, striae much finer than those on rest of body.

Relatively short, mostly erect, off-white or yellowish hairs, scattered over all dorsal body surfaces; hairs longer on apical segments and venter of gaster, some almost as long as greatest diameter of eye. Rather sparse, appressed, silvery pubescence scattered over dorsum of head and mesosoma dense on pronotal humeri, propodeal dorsum, along lateral and posterior borders of gastral segments and especially on metapleuron and propodeal declivity; midline of declivity glabrous.

Black. Mandibular masticatory border widely, inner mandibular border narrowly, light yellowish brown. Antennal scapes dark reddish brown; funiculi brown, segments becoming progressively lighter towards apex, apical segments yellowish brown. Legs very light, yellowish white (unique holotype may not be fully pigmented individual), only basal portion of trochanters, distal ends of femora, proximal ends of tibiae and basal tarsal segments dark, reddish-brown. Sexuals and immature stages unknown.

Type Material
HOLOTYPE: PAPUA NEW GUINEA, East Sepik Prov., 8km SSW of Dagua, 03º29’S, 143º16’E, 800m, lowland rf., 12-14.vii.1980, P.S. Ward #4747-10 (worker). Type distribution: unique holotype in.

Etymology
Name derived from the Latin word planus, meaning flat, alluding to its virtually flat pronotal dorsum.

References based on Global Ant Biodiversity Informatics

 * Janda M., G. D. Alpert, M. L. Borowiec, E. P. Economo, P. Klimes, E. Sarnat, and S. O. Shattuck. 2011. Cheklist of ants described and recorded from New Guinea and associated islands. Available on http://www.newguineants.org/. Accessed on 24th Feb. 2011.
 * Kohout R.J. 2007. Revision of the subgenus Aulacomyrma Emery of the genus Polyrhachis F. Smith, with descriptions of new species (pp. 186-253). In Snelling, R.R., Fisher, B.L. & Ward, P.S. (eds). Advances in ant systematics: homage to E.O. Wilson  50 years of contributions. Memoirs of the American Entomological Institute 80: 690 pp.