Polyrhachis scabra

Nothing is known about the biology of this species.

Identification
Kohout 1987: This species stands close to Polyrhachis magnifica and bears a superficial resemblance to the silvery pubescent population of that species from Mt. Isarog, Luzon Island. The main distinguishing features additional to that given in the key, are the longer antennal scapes of Polyrhachis scabra, along with its more dense sculpturation and a more gracile build.

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

Castes
Males are unknown.

Nomenclature

 *  scabra. Polyrhachis scabra Kohout, 1987: 175, figs. 8, 12, 14 (w.q.) PHILIPPINES.

Worker
Dimensions (holotype cited first, pseudogyne last): TL 14.81, 13.56-15.06, 16.48; HL 3.43, 3.22-3.58, 3.93; HW 2.02, 1.86-2.12, 2.37; CI 59, 58-61, 60; SL 4.74, 4.38-4.89, 5.14; SI 235, 227-237, 217; PW 1.66, 1.56-1.81, 2.02, MTL 6.25, 5.85-6.35, 6.80 (12 measured).

Mandibles with five teeth. Clypeus carinate, sinuate in profile (convex above, concave below). Sides of head in front of eyes almost straight, strongly contracted behind eyes, with narrow occipital margin, lacking lateral angular prominences. Antennal carinae rising sharply, sinuate. Antennal scapes long, extending beyond the occipital margin by about half their length. Eyes convex. Pronotum in profile moderately convex; pronotal spines long, slender, projecting laterally and curved forward. Mesonotal dorsum straight in profile, propodeal dorsum shallowly concave, declivity abrupt. Metanotal groove replaced by a minute ridge. Mesopleural process represented as a dentiform lobe with acute ventral angle. Propodeal spines long, elevated at their bases, diverging and recurved. Petiole with dorsum sloping anteriorly; spines scarcely elevated, short.

Mandibles punctate-opaque with numerous piliferous pits. Sculpturation consists of very fine punctation on clypeus, front and sides of head, increasing posteriorly to densely, but shallowly punctate. Dorsum of mesosoma densely, but shallowly punctate, sculptural intensity increasing laterally to coarsely punctate. Gaster very finely reticulate-punctate.

All body surfaces except antennal scapes with rather diluted, moderately long, undulate, silvery white hairs. These are longest on mesosomal dorsum and shortest on lateral portions of mesosoma, and on the gastral dorsum. Silvery white, somewhat radiating, appressed pubescence abundant over entire body, including gastral dorsum, where it forms the midline pattern characteristic of most members of the group.

Body black with the appendages dark reddish brown. The single pseudogyne (in the terminology of Wheeler, 1910) represents a worker-like form with transversely enlarged mesonotum, which is convex in profile. The sculpturation and pilosity are essentially as in the worker.

Queen
Dimensions: TL 15.51; HL 3.63; HW 2.17; CI 60; SL 4.69; SI 216; PW 2.02; MTL 5.80 (1 measured).

The female differs from the worker in the usual sexual characters, including the reduction in length of pronotal and propodeal spines. The sculpturation and pilosity similar to that in worker.

Type Material
Holotype and 5 paratypes (4 workers and 1 pseudogyne) in BPBM; 3 paratypes (2 workers, 1 dealate female) in RJK, 1 paratype worker each in ANIC, BMNH, USNM and QMBA (with kind consent of Bernice P. Bishop Museum).

References based on Global Ant Biodiversity Informatics

 * Kohout R. J. 1987. Three new Polyrhachis sexspinosa-group species from the Philippines (Hymenoptera: Formicidae). Mem. Qld. Mus. 25: 169-176
 * Robson Simon Database Polyrhachis -05 Sept 2014