Polyrhachis storki

Polyrhachis storki is a widespread but uncommon species.

Identification
A member of the Polyrhachis flavoflagellata species group.

Like Polyrhachis flavoflagellata, P. storki is a widespread but rare species. They are superficially very similar, but undoubtedly distinct. Distinguishing characters include the relative length of the antennal scapes (SI <117 in P. storki versus SI >122 in P. flavoflagellata) and the shape of the anterior clypeal margin. The clypeus of Polyrhachis storki has a bilobed, medially emarginate prominence, while the anterior clypeal margin in P. flavoflagellata is widely truncate with a minute median incision. Polyrhachis storki has a widely rounded petiolar dorsum that bears only a pair of lateral, very weakly elevated spines. In P. flavoflagellata the petiolar dorsum is rather narrow and bears a pair of dorsolaterally directed spines as well as a pair of distinct intercalary teeth.

Distribution
From Peninsular Malaysia to Borneo and south to Sulawesi (Kohout, 2008).

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

Castes
Only known from worker caste.

Nomenclature

 *  storki. Polyrhachis storki Kohout, 2008a: 298, figs. 9C-D (w.) INDONESIA (Sulawesi).

Worker
(holotype cited first): TL c. 6.85, 6.40-7.00; HL 1.72, 1.65-1.75; HW 1.53, 1.47-1.56; CI 89, 89-91; SL 1.72, 1.68-1.81; SI 112, 112-117; PW 1.12, 1.06-1.15; MTL 2.18, 2.12-2.31 (6 measured).

Anterior clypeal margin produced medially into a bilobed, deeply emarginate prominence. Clypeus with blunt, weakly indicated median carina; clypeus in profile very weakly sinuate, shallowly impressed anteriorly, weakly elevated posteriorly with flat, clearly defined basal margin. Frontal triangle distinct. Frontal carinae sinuate, virtually flat, with very weakly raised margins; central area relatively wide, flat; frontal furrow indicated by break in sculpture. Sides of head in front of eyes distinctly converging anteriorly, almost straight, only weakly rounding into mandibular bases; behind eyes strongly rounding into virtually flat occipital margin. Eyes large, weakly convex, in full frontal view situated at posterolateral corners and distinctly breaking lateral cephalic outline. Ocelli lacking. Pronotal humeri armed with distinct, acute teeth. Mesosomal dorsum in profile with distinct, but flat promesonotal suture; metanotal groove indistinct dorsally, weakly indicated laterally; mesonotal and propodeal dorsa almost flat, with poorly defined, blunt, lateral margins. Propodeum armed with pair of dorsoposteriorly directed spines; declivity short, oblique in profile. Petiolar dorsum armed with pair of dorsolaterally directed spines. Anterior face of first gastral segment relatively low with base weakly concave; anterodorsal margin widely rounded.

Mandibles finely, longitudinally striate with numerous piliferous pits. Head, mesosoma and petiole finely and closely reticulate-punctate with sculpturation along occipital margin and on propodeal dorsum somewhat tranversely reticulate, wrinkled. Antennal scapes, legs and gaster more finely reticulate-punctate.

Mandibular masticatory borders with several curved, pale golden hairs. Anterior clypeal margin with single, medium long seta medially and several shorter setae fringing margin laterally. Apex of antennal scapes with very few short hairs. Gaster with only few, short, erect hairs at margins of apical dorsal segments, with somewhat longer hairs lining segments on ventral surfaces. Pale golden, short, closely appressed pubescence in various densities over most body surfaces, notably on mesosoma, petiole and gaster, but nowhere so dense as to hide underlying sculpturation. Pubescence most diluted on head, where it is almost completely absent from clypeus, sides and frontal area, except some scattered, extremely short, appressed hairs raising from piliferous pits.

Colour. Generally dark brown-black with somewhat reddish-brown, almost metalic, hue. Mandibular teeth narrowly reddish-brown; condylae, extreme tip of apical funicular segments and tarsal claws yellowish-brown. Legs very dark reddish-brown with distal portion of front tibiae shade lighter.

Type Material
HOLOTYPYPE: SULAWESI UTARA: Dumoga-Bone NP, 25.ii.1985, mangrove fog., N.E. Stork et al. (worker). PARATYPES: data as for holotype (1 worker). SULAWESI TENGAH: Lore Lindu NP, Toro, Watu Bohe, 860m, 14.iv.2005, cacao agrof., M.M. Bos #34 (1 worker). EAST MALAYSIA, SABAH: Kinabalu Park, Poring, c. 600m, vii.1991, M. Dill (1 worker). WEST MALAYSIA: Negara Sembilan, Pasoh FRFR, xi.1994, fog., M. Brendell, K. Jackson & S. Lewis (3 workers).

Type deposition: Holotype and 1 paratype in, 1 paratype each in , FIS, and.

References based on Global Ant Biodiversity Informatics

 * Kohout R. J. 2008. A new species of the Polyrhachis (Myrmhopla) flavoflagellata-group (Hymenoptera: Formicidae: Formicinae) from Borneo. Asian Myrmecology 2: 11-16.
 * Kohout R. J. 2008. A new species of the Polyrhachis (Myrmhopla) flavoflagellata-group (Hymenoptera: Formicidae: Formicinae) from Borneo. Asian Myrmecology 2:11-16.
 * 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.
 * 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