Polyrhachis imitator

Specimens have been collected from fogging samples in cacao.

Identification
A member of the Polyrhachis aequalis species group.

Kohout (2008) - Polyrhachis imitator is very similar to Polyrhachis incognita, with the main distingushing characters listed in the identification section of the latter. It also bears some resemblance to Polyrhachis aequalis from the Philippines and newly recorded from Sulawesi. However, P. imitator  is larger (HL >1.65 versus <1.56 in P. aequalis) and has well developed pronotal spines that are reduced to short teeth in P. aequalis.

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

Nomenclature

 *  imitator. Polyrhachis imitator Kohout, 2008a: 311, figs. 12A-B (w.q.) INDONESIA (Sulawesi).

Worker
(holotype cited first): TL c. 6.55, 6.50-7.21; HL 1.68, 1.65-1.72; HW 1.47, 1.43-1.53; CI 87, 87-91; SL 1.96, 1.93-1.98; SI 133, 128-137; PW 0.94, 0.90-1.00; MTL 2.18, 2.12-2.25 (11 measured).

Anterior clypeal margin medially with wide, relatively shallow, ‘V’-shaped emargination, flanked by distinct teeth. Clypeus with short median carina; 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 weakly impressed 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; relative positions of lateral ocelli indicated by shallow punctures. Pronotal dorsum weakly convex in profile; humeri with spines marginally longer than their basal widths; outer margins of spines continuous with posteriorly converging lateral pronotal margins. Promesonotal suture distinct; mesonotal dorsum weakly concave between slightly raised, posteriorly converging lateral margins. Propodeal dorsum with lateral margins parallel, terminating posteriorly in relatively long, slender, virtually parallel, dorsoposteriorly directed spines; propodeal dorsum descending into oblique declivity in medially uninterrupted line. Petiole with anterior face straight, posterior face convex; dorsum armed with three, slender, subequal spines; apex of median spine weakly upturned and shallowly emarginate (in holotype and some paratypes) or pointed; lateral spines weakly curved posterolaterally from their bases. Anterior face of first gastral segment flat, widely rounding onto dorsum.

Mandibles very finely, mostly longitudinally rugose with numerous shallow pits. Clypeus finely striate-punctate. Head and mesosoma reticulate-punctate; pronotal dorsum with somewhat irregular, longitudinal, posteriorly bowed rugae. Sides of mesosoma and petiole distinctly reticulate. Gaster finely shagreened.

Mandibles with a few, moderately long, suberect, golden hairs at masticatory borders and extremely short, closely appressed hairs towards their bases. Anterior clypeal margin with a few longer setae medially and fringe of a few, 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 hairs; mid and hind coxae with a few shorter, erect hairs ventrally. Femora and trochanters each with a single, medium length, erect hair on ventral surfaces. Gaster with a few shorter erect hairs along apical segments dorsally; hairs longer and more abundant on gastral venter. Very short, appressed, mostly white pubescence on dorsum of gaster; pubescence virtually absent from rest of dorsal body surfaces.

Colour. Dark reddish-brown, with mandibles, clypeus, coxae, most of legs and gaster medium reddish-brown; condylae, apical segments of funiculi and mandibular masticatory borders, light yellowish-brown.

Queen
TL c. 9.78; HL 2.25; HW 1.90; CI 84; SL 2.40; SI 126; PW 1.84; MTL 2.93 (1 measured).

Apart from sexual characters and larger size, closely resembling worker except: pronotal humeri armed with blunt teeth; mesoscutum with virtually flat dorsum and lateral margins converging anteriorly towards rather narrowly rounded anterior margin; median line distinct, parapsides flat; mesoscutellum marginally elevated above dorsal plane of mesoscutum. Propodeum armed with strong, somewhat dorsally flattened, obliquely directed spines; petiolar spines shorter than in worker, median spine marginally shorter than lateral spines. Sculpturation and colour virtually as in worker.

Type Material
HOLOTYPE: SULAWESI TENGAH, Lore Lindu NP, Toro, Haloda, 815m, 17.iv.2005, cacao fog., M.M. Bos (worker). PARATYPES: data as for holotype (10 workers, 1 queen). Holotype worker (QMT144153), 2 paratype workers and paratype queen in ; 2 paratype workers each in, , GUGG (Bos coll.) and.

References based on Global Ant Biodiversity Informatics

 * Kohout R.J. 2008. A new Polyrhachis (Myrma) vestita-group species from Sulawesi. Zoologische Mededeelingen, Leiden 82: 297-302.
 * 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.