Polyrhachis palawanensis

Identification
Polyrhachis palawanensis closely resembles Polyrhachis pubescens and Polyrhachis alatisquamis. All have short to medium length, semierect to erect, bristle-like hairs and abundant, relatively long, silvery, appressed pubescence. Polyrhachis palawanensis and P. alatisquamis both have a transversely broad petiole distinguishing them from P. pubescens. In addition, P. palawanensis has unusually flat, posteriorly protracted eyes, which distinguish it from both of the above species.

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

Castes
Sexuals and immature stages unknown.

Nomenclature

 *  palawanensis. Polyrhachis (Myrma) palawanensis Kohout, 2013: 155, figs. 27-31 (w.) PHILIPPINES.

Worker
Dimensions: TL c. 6.60; HL 1.62; HW 1.31; CI 81; SL 2.06; SI 157; PW 1.28; MTL 2.00 (1 measured).

Mandibles with 5 teeth. Anterior clypeal margin arcuate, distinctly truncate medially, truncate portion delimited laterally by blunt angles. Clypeus with poorly indicated median carina; virtually straight in profile, posteriorly rounding into moderately impressed basal margin. Frontal triangle poorly indicated. Frontal carinae sinuate, margins only moderately raised; central area flat with rather short frontal furrow. Sides of head in front of eyes convex towards mandibular bases; behind eyes sides strongly converging towards rather narrow occipital margin. Eyes very prominent, virtually flat, strongly projecting laterally, resembling blinkers, outline somewhat angular in full face view (Fig. 27); flatness of eyes notably evident when viewed from behind (Fig. 28). Ocelli lacking. Pronotal dorsum armed with relatively long spines, about 2x as long as basal width; pronotal margins subparallel, rounding posteriorly into promesonotal suture that is distinctly impressed laterally and rather flat medially. Mesonotal lateral margins narrowly rounded and raised anteriorly, posteriorly rounding into laterally impressed, medially indistinct, metanotal groove. Propodeal dorsum with lateral margins distinctly converging posteriorly and terminating in narrowly rounded, dorsally raised ridges that are continued medially and form transverse, dorsally bowed carina separating propodeal dorsum from virtually vertical, concave declivity. Secondary carinae extending from propodeal margins towards propodeal spiracles, dividing declivity from sides of propodeum. Petiole biconvex in profile; dorsum strongly transverse with weakly convex dorsal margin armed with pair of dorsolaterally and posteriorly directed spines situated on dorsolateral angles of petiole; shorter, rather flat, secondary spine situated laterally at base of each spine (Fig. 29). Anterior face of first gastral segment concave to accommodate posterior face of petiole; anterior margin only narrowly rounding onto dorsum.

Mandibles distinctly, longitudinally striate with piliferous pits. Clypeus reticulate punctate with rest of head and dorsum of mesosoma, including spines, distinctly, rather regularly, longitudinally striate, opaque. Sides of mesosoma wrinkled; petiole finely reticulate. Tips of pronotal and petiolar spines smooth, polished. Gaster distinctly, rather closely reticulate-punctate, opaque.

Mandibular masticatory borders and outer margins with numerous, suberect, golden hairs. Anterior clypeal margin medially with a few anteriorly directed golden setae and few shorter setae fringing margin laterally. Numerous relatively long, erect or suberect, mostly silvery or whitish hairs on clypeus, along frontal carinae, vertex and sides of head; moderately long, suberect hairs lining superior edge of antennal scapes with only a few distinctly shorter hairs along inferior edge. A few shorter, silvery hairs on sides of pronotum and fore coxae; more abundant, somewhat longer, pale golden hairs on legs. Hairs virtually absent from dorsum of mesosoma and petiole. Several moderately long, pale golden hairs on dorsum of gaster, distinctly longer and more abundant hairs on gastral venter and around apex. Closely appressed, relatively long, white or greyish pubescence abundant over most body surfaces and almost completely hiding underlying sculpturation; pubescence somewhat less abundant on antennal scapes and legs and completely absent from mandibles and tips of spines.

Colour. Black; mandibular masticatory borders lined with reddish brown. Antennae, legs and gastral apex dark to medium reddish brown.

Etymology
Named after the type locality, Palawan Island in the Philippines.