Polyrhachis lepida

Polyrhachis lepida usually build nests between leaves in the lower arboreal zone. However, one nest was located in a hollow internode of a dry bamboo stem lying on the ground. (Kohout 2006)

Identification
Polyrhachis lepida is somewhat similar to Polyrhachis rastellata, but can be distinguished by its generally smaller size, distinctly more convex occiput and longer antennal scapes (SI 128-136 versus 111-123 in Polyrhachis rastellata). They also differ in the configuration of the petiolar spines with the lateral pair in Polyrhachis lepida distinctly longer than the dorsal pair. In contrast, the petiolar spines in Polyrhachis rastellata are subequal or the lateral pair is somewhat shorter than the dorsal pair. The two species also differ in the colour of their legs with those of Polyrhachis lepida consistently darker. (Kohout 2006)

Distribution
Endemic to Borneo and distributed throughout the island (Kohout 2006).

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia, Singapore.

Abundance
Polyrhachis lepida is a relatively common species along the edges of rainforest clearings from the lowlands to higher altitudes.

Castes
Undescribed males have been deposited in the collection. The immature stages are unknown. (Kohout 2006)

Nomenclature

 *  lepida. Polyrhachis lepida Kohout, 2006b: 113, figs. 7A-B (w.q.m.) BORNEO.

Worker
Dimensions (holotype cited first): TL c. 5.90, 5.64-6.00; HL 1.47, 1.40-1.50; HW 1.34, 1.28-1.37; CI 91, 89-93; SL 1.78,1.68-1.81; SI 133, 128-136; PW 1.15, 1.09-1.18; MTL 2.03, 1.96-2.12 (12 measured).

Clypeus in profile almost straight anteriorly, posteriorly rounding into moderately impressed basal margin. Frontal triangle indistinct. Frontal carinae sinuate with weakly raised margins; central area weakly concave with poorly defined, short furrow. Sides of head in front of eyes very weakly convex, converging anteriorly; behind eyes rounding into convex occipital margin. Eyes in full face view clearly breaking lateral cephalic outline. Ocelli lacking; relative positions of lateral ocelli indicated by weak punctures in cephalic sculpture. Pronotum in dorsal view with greatest width across narrowly rounded or subangular humeri. Mesosoma in profile with pronotum convex anteriorly, mesonotum and propodeum weakly convex; promesonotal suture distinct; position of metanotal groove indicated by weak impression in lateral outline; propodeum unarmed or with rudimentary tubercles in some specimens; propodeal dorsum rounding rather abruptly into steep declivity. Petiole with anterior face almost straight, posterior face convex; dorsum armed with pair of short, broad-based dorsal teeth and pair of distinctly longer and slender lateral spines. Subpetiolar process acute anteriorly, obtusely angular posteriorly. Anterior face of first gastral segment in lateral view relatively low, straight, narrowly rounding onto dorsum of segment.

Mandible very finely, mostly longitudinally rugose with numerous piliferous pits. Dorsa of head, mesosoma and gaster finely and uniformly shagreened, rather polished, with numerous shallow punctures. Intensity of mesosomal sculpturation increasing laterally, becoming coarsely reticulate-rugose with meso- and metapleurae distinctly rugose. Petiole finely transversely wrinkled, more rugose around base.

Mandibles with several semierect and curved, short hairs, notably towards outer margins and masticatory borders. Single pair of relatively long, anteriorly directed setae medially on anterior clypeal margin, a few distinctly shorter setae lining margin laterally. Several pairs of relatively short hairs arising near anterior and basal clypeal margins, along frontal carinae and on vertex. Anterior face of fore coxae, trochanters and proximal ends of fore femora on ventral aspect with a few longer hairs. Gaster with relatively few erect hairs lining posterior margins of apical segments. Whole body with extremely short appressed hairs arising from numerous shallow punctures.

Colour. Black; mandibular teeth, condylae and extreme tips of apical funicular segments reddish-brown. Legs, including trochanters, light to medium reddish-brown with distal ends of femora and tibiae very narrowly, and proximal ends of tibiae widely, black. Coxae and tarsi black.

Queen
Dimensions: TL c. 6.80-7.61; HL 1.50-1.65; HW 1.40-1.56; CI 91-94; SL 1.78-1.93; SI 120-129; PW 1.43-1.72; MTL 2.18-2.43 (7 measured). Apart from sexual characters, very closely resembling worker except: pronotal humeri rounded; mesoscutum wider than long with lateral margins converging anteriorly, anterior margin narrowly rounded; median line weakly indicated, short; parapsides rather flat; mesoscutellum in profile weakly convex, only marginally elevated above dorsum of mesosoma; metanotal groove distinct; propodeum in some specimens with indistinct, rudimentary tubercles; propodeal dorsum convex or almost straight in profile, descending into oblique declivity in rather blunt angle.

Type Material
HOLOTYPE: EAST MALAYSIA, SABAH, Kinabalu Park, Poring, 06°02’N, 116°43’E, c. 500m, 30.x.2000, rf edge, R.J. Kohout acc. 2000.181 (worker). PARATYPES: data as for holotype (11 workers). Type deposition: Holotype (QMT99344) and 2 paratypes in ; 2 paratypes each, , ; 1 paratype each , and.

References based on Global Ant Biodiversity Informatics

 * Fayle T. M., E. C. Turner, J. L. Snaddon, V. Khen Chey, A. Y. C. Chung, P. Eggleton, and W. A. Foster. 2010. Oil palm expansion into rain forest greatly reduces ant biodiversity in canopy, epiphytes and leaf-litter. Basic and Applied Ecology 11: 337345.
 * Kohout R.J. 2006. Review of Polyrhachis (Cyrtomyrma) Forel of Australia, Borneo, New Guinea and the Solomon Islands with descriptions of new species. Memoirs of the Queensland Museum 52: 87-146.
 * Kohout R.J., and M. Mohamed. 2008. A preliminary list of the Polyrhachis ants of the Maliau Basin Conservation area in Sabah, Borneo (Hymenoptera: Formicidae: Formicinae). Asian Myrmecology 2: 63-70.
 * Pfeiffer M.; Mezger, D.; Hosoishi, S.; Bakhtiar, E. Y.; Kohout, R. J. 2011. The Formicidae of Borneo (Insecta: Hymenoptera): a preliminary species list. Asian Myrmecology 4:9-58
 * Yusah K. M., T. M. Fayle, G. Harris, and W. A. Foster. 2012. Optimizing diversity assesment protocols for high canopy ants in tropical rain forest. Biotropica 44(1): 73-81.