Polyrhachis incognita

Specimens have been collected from fogging samples in cacao.

Identification
A member of the Polyrhachis aequalis species group.

Kohout (2008) - Polyrhachis incognita can be distinguished from the other Sulawesian Myrmothrinax species (except Polyrhachis imitator), by the deep, ‘V’-shaped median emargination of the anterior clypeal margin and its large size and mostly black head and mesosoma. It differs from P. imitator  by its virtually flat pronotal dorsum, somewhat longer antennal scapes (SL >2.00 versus SL <2.00 in P. imitator), distinctly shorter, wide-based, upturned propodeal spines and generally darker body. The two non-type specimens collected by Fruhstorfer compare well with the holotype and I consider them conspecific. Both bear identification tags in Mayr’s handwriting as indicated in the above notes on Polyrhachis javanica.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Indonesia, Sulawesi.

Nomenclature

 *  incognita. Polyrhachis incognita Kohout, 2008a: 312, figs. 12C-D (w.q.) INDONESIA (Sulawesi).

Worker
(holotype cited first): TL c. 6.80, 6.65-7.61; HL 1.75, 1.68-1.75; HW 1.53, 1.47-1.53; CI 87, 87; SL 2.12, 2.03-2.21; SI 138, 138-147; PW 1.06, 1.00-1.06; MTL 2.34, 2.18-2.53 (4 measured).

Anterior clypeal margin medially with wide, deep, ‘V’-shaped emargination, flanked by rather blunt teeth. Clypeus with short median carina; clypeus weakly convex in profile, rounding into deeply impressed basal margin, laterally basal margin indicated by thin, sculpture-breaking line. Frontal triangle weakly indicated. Frontal carinae sinuate with narrowly raised margins; central area relatively wide with poorly indicated frontal furrow. Sides of head in front of eyes converging towards mandibular bases in almost straight line; behind eyes sides widely rounding into weakly convex occipital margin. Eyes convex, in full face view clearly exceeding lateral cephalic outline. Ocelli lacking. Pronotal dorsum flat; humeri with spines distinctly longer than their basal widths, directed anterolaterally and weakly downward; outer margins of spines merging with posteriorly converging, lateral pronotal margins. Promesonotal suture distinct; mesonotal dorsum weakly concave in profile; lateral mesonotal margins distinctly raised and strongly converging towards distinct metanotal groove. Propodeal dorsum relatively narrow with lateral margins parallel, terminating posteriorly in rather short, broad-based, upturned spines; propodeal dorsum descending into oblique declivity in medially uninterrupted line. Petiole with anterior face straight, posterior face convex; dorsum armed with three, broad-based, subequal spines; lateral pair weakly curved posterolaterally from their bases. Anterior face of first gastral segment flat, widely rounding onto dorsum.

Mandibles very finely striate with numerous shallow pits. Clypeus finely, anteromedially striate-punctate. Sides of head and vertex reticulate-punctate with sculpture in front of eyes mostly longitudinally directed. Pronotal and mesonotal dorsa longitudinally striate-punctate with striae on pronotum bowed towards posterior corners. Sides of mesosoma reticulate-punctate with petiole distinctly punctate-rugose. Gaster finely shagreened.

Mandibles with a few, short, mostly erect, golden hairs at masticatory borders and extremely short, closely appressed hairs towards bases. Anterior clypeal margin with a few longer setae medially and fringe of short setae laterally. A few pairs of short, erect hairs near anterior and basal clypeal margins, along frontal carinae and a single pair on vertex. Anterior, posterior and ventral faces of fore coxae with a few, relatively long, somewhat curved hairs; mid and hind coxae with a few shorter erect hairs ventrally. Femora with a few, medium length, erect hairs on ventral surfaces. Gaster with few short, erect hairs lining apical segments dorsally, more abundant, longer hairs on gastral venter. Very short, appressed, mostly white pubescence on dorsum of gaster; pubescence virtually absent from rest of dorsal body surfaces.

Colour. Holotype and associated queen black, with mandibular masticatory border, condylae and apical segments of funiculi medium to dark reddish-brown. Paratypes generally a shade lighter with legs, including coxae, and gaster dark to very dark reddish-brown.

Queen
TL c. 8.26; HL 2.00; HW 1.68; CI 84; SL 2.18; SI 130; PW 1.56; MTL 2.53 (1 measured).

Apart from sexual characters and larger size, closely resembling worker except: pronotal humeri armed with blunt, but distinct teeth; mesoscutum with virtually flat dorsum; lateral margins rather strongly converging anteriorly, forming narrowly rounded anterior margin; median line short; mesoscutellum marginally elevated above dorsal plane of mesoscutum. Propodeum armed with strong, relatively short, upturned spines; petiolar spines subequal, shorter than in worker. Sculpturation and colour virtually as in holotype worker.

Type Material
HOLOTYPE: SULAWESI TENGAH, Lore Lindu NP, Toro, Powawua, 810m, 18.iv.2005, cacao fog., M.M. Bos (worker). PARATYPES: data as for holotype (2 workers, 1 queen). SULAWESI UTARA, Dumoga-Bone NP, Tumpah R., 7.x.1985, Bosmans & Van Stalle #004) (1 worker). Holotype worker (QMT144154) and paratype queen in ; 1 paratype worker each in GUGG (Bos coll.), and.

References based on Global Ant Biodiversity Informatics

 * Kohout, R. J. 2008. A review of the Polyrhachis ants of Sulawesi with keys and descriptions of new species (Hymenoptera: Formicidae: Formicinae). Memoirs of the Queensland Museum 52:255-317.