Polyrhachis dispar

Nothing is known about the biology of .

Identification
A member of the Polyrhachis sexspinosa species group.

Kohout (2010) - With its relatively broad occipital margin, Polyrhachis dispar is easily recognised within the sexspinosa-group. It is most similar to Polyrhachis reclinata and, in addition to the lack of lateral occipital lobes, it can be distinguished by its less convex pronotal dorsum and distinctly rugose dorsum of the head and mesosoma. The pronotal dorsum in P. reclinata is distinctly higher and the sculpturation of the vertex, sides of head and pronotal dorsum consists of very fine reticulation beneath a rich pubescence that is much more diluted in P. dispar. Also, the mesopleural process in P. dispar is present as a blunt, simple lobe, while in P. reclinata the lobe is ventrally dentiform.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Castes
Male unknown. Immature stages (larvae of various stages of development and pupae) in QM spirit collection.

Nomenclature

 *  dispar. Polyrhachis dispar Kohout, 2010: 185, figs. 4A,C-D, 8A (w.q.) AUSTRALIA.

Worker
(holotype cited first) TL c. 13.10, 11.39-14.10; HL 3.12, 2.87-3.40; HW 2.12, 2.02-2.44; CI 68, 68-74; SL 3.43, 3.17-3.72; SI 162, 152-165; PW 1.75, 1.51-1.96; MTL 4.33, 4.08-4.69 (25 measured).

Anterior clypeal margin arcuate, with shallow emargination medially; clypeus with distinct, blunt, median carina; clypeus virtually straight in profile, posteriorly rounding into moderately impressed basal margin. Frontal triangle distinct. Frontal carinae sinuate with acute, almost vertically raised margins; central area relatively narrow with distinct posterior carina. Sides of head in front of eyes weakly convex; behind eyes sides converging into relatively wide occipital margin. Eyes strongly convex, in full face view exceeding lateral cephalic outline. Median ocellus poorly developed, lateral ocelli lacking; positions indicated by distinctly raised cephalic sculpture. Pronotal dorsum weakly convex in profile; humeri armed with strong, acute, more-or-less horizontal, anterolaterally curved spines; promesonotal suture distinct. Mesonotum rather flat in profile; mesopleural process a blunt, simple lobe. Propodeal spines relatively long, obliquely elevated from their bases, curved posteriorly and moderately divergent. Dorsum of petiole with a pair of laterally and posteriorly directed, acute spines, with their tips turned slightly downwards.

Clypeus finely reticulate-punctate; sides of head in front of eyes smooth and polished; sculpturation on head increasing in density and intensity posteriorly, vertex and sides towards occipital margin coarsely sculptured. Dorsum and sides of mesosoma rugose; sculptural intensity decreasing posteriorly with propodeal dorsum and declivity relatively smooth. Gaster very finely shagreened.

Mostly whitish or pale yellow hairs present over all body and appendages, including antennal scapes and spines, with longest hairs on pronotal and mesonotal dorsa exceeding greatest diameter of eye in length. Rather diluted, mostly greyish, appressed or suberect pubescence variously developed, most dense and more appressed on clypeus, dorsal mesosoma and petiole, somewhat suberect and variously radiating on sides of mesosoma. Sides of head and vertex with distinctly less dense, suberect pubescence partly revealing underlying sculpturation. Gaster with relatively long, mostly golden appressed pubescence, ranging from somewhat diluted on venter to dense on dorsum, where it is arranged in a characteristic midline pattern.

Body generally black; mesosoma and petiole in some specimens very dark reddish-brown; masticatory borders of mandibles, apical antennal segments and legs, except tarsi, medium reddish-brown.

Queen
(paratype queen cited first) TL c. 14.08, 13.18-14.21; HL 3.17, 3.07-3.38; HW 2.17, 2.17-2.47; CI 68, 68-73; SL 3.43, 3.28-3.73; SI 158, 148-159; PW 2.37, 2.42-2.57; MTL 4.33, 4.23-4.74 (5 measured).

Very similar to worker with usual differences indicating full sexuality. Mesoscutum virtually as wide as long with lateral margins converging anteriorly into narrowly rounded margin; median line slightly raised; dorsum rather low and flat in lateral view with parapsides only weakly raised posteriorly. Mesoscutellum flat, not elevated above dorsal plane of mesosoma; metanotal groove distinct. Spines similar to those in worker, but shorter with propodeal pair distinctly less elevated. Sculpturation, pilosity, pubescence and colour virtually identical to worker.

Type Material
HOLOTYPE: QUEENSLAND, Cape York Pen., Iron Ra., 12º43’S, 143º18’E, 26-31.vii.1981, rf., ex nest in dry bamboo internode, R. J. Kohout acc. 81.202 (worker). PARATYPES: data (and nest) as for holotype (64 workers, alate queen); data as for holotype, except RJK accs 81.148, 195 (8 paratype workers); Cape York, W.B. Barnard (2 workers from original series of P. barnardi Clark in & ). Type deposition: Holotype (QM T152321), most paratype workers and paratype queen (from holotype nest) in QM; 4 paratype workers (2 from holotype nest) each in ANIC, and MCZC; 2 paratype workers each in, , , , ,  and NMHU.

Kohout & Taylor (1990: 519) examined all the available specimens of the Polyrhachis barnardi Clark, 1928 type series and concluded that it comprised two distinct species. The lectotype (originally furnished with a red tag inscribed ‘Type’) and two paralectotypes (all MVMA) were identified as Polyrhachis sexspinosa (Latreille) and, consequently, P. barnardi has been considered a synonym of that species. Two remaining paralectotypes (that match Clark’s original description and illustrations of P. barnardi) were deposited in other institutions (ANIC, MCZC) and are included in the type series of P. dispar.