Polyrhachis shattucki

Polyrhachis shattucki is apparently rare and has been collected only twice, the type series consisting of nocturnal stray workers on the ground in a savannah woodland.

Identification
A member of the Polyrhachis micans species-group.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Castes
Male and immature stages unknown.

Nomenclature

 *  shattucki. Polyrhachis (Campomyrma) shattucki Kohout, 2013: 115, figs. 8A-D (w.) AUSTRALIA.

Taxonomic Notes
This species was listed in a key to species of the P. micans-group as “P. ‘Campo 12’ (undescribed)” (Kohout, 2008: 165).

Worker
(holotype cited first): TL c. 9.07, 7.66-9.07.87; HL 2.12, 1.93-2.18; HW 1.93, 1.72-2.06; CI 91, 89-94; SL 1.90, 1.75-1.90; SI 98, 92-103; PW 1.68, 1.59-1.81; MTL 2.34, 2.12-2.34 (1 + 15 measured).

Mandibles with 5 teeth. Anterior clypeal margin widely medially truncate, truncate portion more-or-less regularly denticulate. Clypeus with flat, rather indistinct median carina; virtually straight in profile, only very weakly raised towards anterior margin; basal margin flat. Frontal triangle distinct. Frontal carinae sinuate with only very weakly and narrowly raised margins; central area wide with poorly indicated frontal furrow. Sides of head in front of eyes virtually straight, only weakly rounding towards mandibular bases; behind eyes sides forming short, narrowly rounded occipital corners. Eyes only moderately convex, in full face view breaking lateral cephalic outline. Ocelli lacking. Pronotal dorsum distinctly wider than long; humeri bluntly angular with rather distinct anterior margins converging towards occipital collar; lateral pronotal margins converging towards well impressed, anteriorly bowed promesonotal suture. Mesonotal lateral margins converging posteriorly into poorly indicated, shallowly impressed, metanotal groove. Propodeal margins weakly raised, converging posteriorly and terminating in short, upturned, somewhat dorsoanteriorly flattened, acute teeth; propodeal dorsum between them curving into steep, almost vertical declivity. Petiole scale-like, very slender in lateral view; dorsum armed with a pair of slender medium length, subparallel spines; inner margins of spines continuous medially, forming 'U'-shaped dorsum of petiole; outer margins of spines steeply descending into rather blunt, lateral angles. Anterior face of first gastral segment virtually flat, lower than full height of petiole, narrowly rounding onto dorsum of gaster.

Mandibles closely and finely, longitudinally striate with piliferolls pits. Clypeus reticulate-punctate. Head reticulate-punctate with sculpturation on vertex and along frontal carinae organised into longitudinal striae. Dorsum of mesosoma somewhat more finely, longitudinally, reticulate-striate with sides finely wrinkled. Petiole, including spines, very finely wrinkled. Gaster very closely and finely reticulate-punctate, semiopaque.

Mandibles towards masticatory borders with numerous curved, golden hairs. Anterior clypeal margin medially with several, anteriorly directed, uneven length golden setae and very short setae fringing margin laterally. A pair of medium length golden hairs near anterior clypeal margin laterally and a few hairs on fore coxae and venter of femora. Gaster with rather long, posteriorly inclined, golden hairs on venter and around apex, some as long as greatest diameter of eyes. Very short, appressed, silvery pubescence in various densities over most body surfaces, most abundant on dorsum of gaster.

Black; mandibles medium reddish-brown, light red band at masticatory borders, teeth black. Antennal scapes and basal funicular segments very dark reddish-brown; apical funicular segments progressively lighter towards apices. Middle and hind coxae, femora and fore tibiae medium reddish-brown; middle and hind tibiae a shade darker; tarsi very dark, almost black. Dorsum of gaster black; sides and venter reddish-brown, with margins of segments lined with dark reddish-brown or black; apex a shade lighter.

Queen
TL c. 9.22; HL 2.12; HW 1.87; CI 88; SL 1.84; SI 98; PW 2.06; MTL 2.25 (1 measured).

Queen very similar to worker and apart from characters identifying full sexuality, including three ocelli, complete thoracic structure and wings, differing as follows: clypeus with blunt, anteriorly distinct, median carina; eyes larger; pronotal humeri bluntly angular with anterior margins less distinct and shorter. Mesoscutum with anterior margin widely rounded in dorsal view, distinctly wider than long; median line very short; parapsides flat; mesoscutum in profile with relatively low anterior face, widely rounding onto flat dorsum. Mesoscutellum not elevated above dorsal plane of mesosma, weakly convex, postetiorly rounded into well impressed metanotal groove; propodeum wider than long with lateral margins strongly converging posteriorly, terminating in upturned teeth. Petiole with dorsal spines distinctly shorter. Sculpturation, pilosity and colour scheme virtually identical to worker.

Etymology
Named in honour of Dr Steve O. Shattuck of the ANIC, CSIRO Division of Entomology, Canberra, in appreciation of his support and encouragement towards my work on Polyrhachis and for invaluable help in providing many of the excellent digital images that illustrate my continuing work on these highly interesting ants.