Polyrhachis undulata

Nothing is known about the biology of  Polyrhachis undulata.

Identification
Similar to Polyrhachis emeryana and Polyrhachis pacifica. These other two species have a similar highly convex pronotum with the mesonotum and propodeum descending posteriorly in an uneven, stepped outline. Polyrhachis undulata shares the unevenly descending mesosomal profile but differs from Polyrhachis pacifica by a complete lack of propodeal spines and from Polyrhachis emeryana by distinctly angular pronotal humeri. Polyrhachis undulata also differs from both by its larger size (HL 1.53-1.59 in Polyrhachis undulata versus 1.28-1.34 in Polyrhachis pacifica and 1.34-1.40 in Polyrhachis emeryana) and in having the mesonotal dorsum distinctly higher than the pronotum. In Polyrhachis pacifica and Polyrhachis emeryana the summit of the pronotal dorsum is the highest point of mesosoma. (Kohout 2006)

Distribution
Solomon Islands

This taxon was described from Solomon Is.

Castes
Known only from workers.

Worker
Dimensions (holotype cited first): TL c. 6.30, 6.00-6.35; HL 1.59, 1.53-1.59; HW 1.50, 1.43-1.50; CI 94, 92-94; SL 1.72, 1.59-1.72; SI 115, 111-117; PW 1.25, 1.12-1.25; MTL 2.09, 2.00-2.09 (3 measured).

Clypeus in profile very weakly, evenly convex with weakly and narrowly impressed basal margin, indicated laterally by distinct line. Frontal triangle weakly impressed. Frontal carinae sinuate with weakly raised margins; central area weakly concave medially with rather faint frontal furrow. Sides of head in front of eyes straight, converging towards mandibular bases; behind eyes sides rounding into moderately convex occipital margin. Eyes moderately convex, in full face view just reaching or, at most, only marginally breaking lateral cephalic outline. Ocelli lacking; relative position of median ocellus indicated by small pit in cephalic sculpture. Pronotum in dorsal view with humeri obtusely angular. Mesosoma in profile with pronotal dorsum convex; promesonotal suture distinctly impressed; mesonotal dorsum convex, elevated above pronotum; metanotal groove indistinct dorsally, laterally evident as very short furrow; propodeum descending posteriorly in stepped outline, armed with pair of more-or-less distinct tuberculae; declivity very steep. Petiole with anterior face straight, posterior face weakly convex; dorsum armed with four acute spines, lateral pair slightly longer and more slender than dorsal pair. Subpetiolar process angulate anteriorly, widely rounded posteriorly. Anterior face of first gastral segment straight, narrowly rounding onto dorsum of segment.

Mandibles very finely rugose with numerous piliferous pits. Head, mesosoma and gaster shagreened with sides of pronotum and meso- and metapleurae reticulate to reticulate-rugose.

Mandibles with numerous semierect hairs at masticatory borders and very short appressed hairs arising from pits towards mandibular bases. A few long, anteriorly directed setae on clypeal margin medially and a few very short setae laterally. Two pairs of erect hairs arising near anterior clypeal margin; single pair of medium length, somewhat curved hairs on summit of mesonotum. Gaster with short to medium length, erect hairs lining posterior margins of apical segments, more numerous on ventral surfaces. Whole body densely covered with very short, appressed hairs arising from shallow punctures and pits.

Colour. Black, including proximal half of antennal scapes, coxae and tarsi. Mandibles, condylae, distal half of antennal scapes, funiculi, trochanters, femora, tibiae and apex of gaster dark to very dark reddish-brown. Mandibular masticatory borders and tips of apical funicular segments a shade lighter.

Queen
Unknown

Male
Unknown

Type Material
Holotype and 1 paratype in, 1 paratype each in , and.

Type Locality Information
HOLOTYPE: SOLOMON IS, Guadalcanal, Mt Austen, 09°29’S, 159°59’E, 13.xi.1964, P.J.M. Greenslade #15093 (worker). PARATYPES: data as for holotype (1 worker); data as for holotype, except 21.iv.1965, P.J.M. Greenslade #16888 (3 workers).