Polyrhachis xiphias

Identification
A member of the xiphias species-group. Kohout (2013) - Polyrhachis xiphias is quite similar to both the other species of the group, P. hashimotoi and P. shixingensis, but can be easily distinguished by the more convex eyes, more-or-less distinct, though rather blunt, humeral angles and divergent petiolar spines. In contrast, the other two species have distinctly flatter eyes, smoothly rounded pronotal humeri and subparallel petiolar spines.

Key to Polyrhachis xiphias group species

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

Castes
Males have yet to be collected.

Nomenclature

 *  xiphias. Polyrhachis xiphias Smith, F. 1863: 16 (q.) NEW GUINEA. Kohout, 2013a: 25, figs. 3, 8, 9, 11, 14, 15 (w.q.). Combination in P. (Hagiomyrma): Emery, 1925b: 185; in P. (Campomyrma): Kohout, 2013b: 492.

Kohout (2013b): Polyrhachis xiphias was described from a single queen and subsequently placed by Emery (1925: 185) in the subgenus Hagiomyrma. Only following the recent identification of worker specimens was P. xiphias recognised as a member of the subgenus Campomyrma Wheeler. It became the name-bearing species of the Polyrhachis xiphias-group (Kohout 2007: 7), a small group of species within Campomyrma, which also includes Polyrhachis hashimotoi Kohout from Borneo and Polyrhachis shixingensis Wu & Wang from China. The members of this group differ from other Campomyrma species by having the petiolar node columnar and the dorsum armed with two, more-or-less horizontal, posteriorly directed spines, in contrast to the scale-like petiole of all other known Campomyrma species.

Description
Kohout (2013):

Worker
TL c. 6.00-6.80; HL 1.50-1.72; HW 1.40-1.59; CI 91-94; SL 1.62-1.78; SI 110-117; PW 1.06-1.18; MTL 1.72-1.96 (11 measured)

Anterior clypeal margin medially truncate with truncate portion jagged and shallowly notched. Clypeus with blunt median carina, straight in profile; basal margin only very shallowly impressed. Frontal triangle distinct. Frontal carinae sinuate, only weakly raised; central area relatively wide with shallowly impressed frontal furrow. Sides of head in front of eyes evenly rounding into mandibular bases; behind eyes sides rather abruptly and narrowly rounding onto virtually flat occipital margin. Eyes moderately convex, in full-face view clearly breaking lateral cephalic outline. Ocelli lacking. Pronotum in dorsal view with lateral margins rounded with only indication of rather blunt humeral angles in some specimens. Promesonotal suture distinctly impressed; mesonotum with lateral margins converging towards distinct metanotal groove. Propodeal dorsum with lateral margins weakly divergent, terminating posteriorly in more-or-less dorsally flattened spines; inner margins of spines continuous medially, forming an inverse ‘U’-shaped carina separating propodeal dorsum from steeply descending declivity. Petiolar node with anterior and posterior faces subparallel; dorsum of petiole with a pair of blunt, posteriorly directed, intercalary teeth and relatively short, divergent spines. Anterior face of first gastral segment straight at base, only marginally higher than full height of petiole, narrowly rounding onto dorsum.

Mandibles very finely, longitudinally striate with numerous piliferous pits. Head and dorsum of mesosoma reticulate-punctate, sides of mesosoma and petiole finely wrinkled. Gaster very finely shagreened, rather polished.

Mandibular masticatory borders with only a few relatively short, curved, golden hairs. Anterior clypeal margin with several golden setae medially; clypeus, frontal carinae and vertex with several paired, medium-length, erect hairs. Fore coxae with several semierect hairs and a few hairs on ventral surfaces of middle and hind coxae. Gaster with several longer hairs on venter and around apex. Extremely short, much diluted, appressed pubescence distributed very sparingly over most body surfaces.

Black; narrow band at mandibular masticatory borders medium reddish-brown. Antennal scapes dark brown; funiculi dark brown at bases, with segments progressively lighter towards funicular apices; condylae light yellow. Legs light yellow with joints of femora and tibiae, and tarsi dark brown.

Queen
Dimensions (holotype cited first): TL c. 10.89, 10.33; HL 2.47, 2.40; HW 1.99, 2.03; CI 80, 84; SL 2.32, 2.31; SI 116, 114; PW 1.66, 1.72; MTL 2.72, 2.65 (2 measured)

Queen very similar to worker with usual characters of full sexuality and shorter propodeal spines. Mesoscutum relatively low with flat dorsum; mesoscutellum not elevated above dorsal plane of mesosoma. Sculpturation of head distinctly finer than in worker; mesoscutum very finely, longitudinally striate anteriorly, striae somewhat less distinct posteriorly; mesoscutellum very finely striate. Propodeum very finely reticulate-punctate. Gaster shagreened, rather highly polished. Pilosity and pubescence almost identical to that in worker. Colour similar to that in worker, only legs distinctly darker, medium reddish-brown.

Type Material
Kohout (2013) - Holotype queen. Type locality: NEW GUINEA, Waigiou I. (= INDONESIA, Pulau Waigeo) (A. R. Wallace), (Type HYM:1064)).



Holotype queen in. Labelled “Wag” (= Waigeo I., New Guinea) and with a Donisthorpe type-label.