Polyrhachis archeri

Polyrhachis archeri is a ground-nesting species, with the type series specimens collected foraging near a nest entrance hidden under a small rock.

Identification
A member of the penelope species-group in the Polyrhachis subgenus Hagiomyrma. Kohout (2013) - Polyrhachis archeri is very similar to Polyrhachis anderseni, with most of the distinguishing characters listed in the remarks on the latter species. It is also similar to Polyrhachis hoffmanni, which shares the same type locality with P. archeri. Polyrhachis hoffmanni is easily separated by the presence of relatively long hairs over most body surfaces which are completely absent in both the other species.

Distribution
The distribution of P. archeri appears to be centred on the Gulf Country in north-western Queensland, however, it has recently been collected in the Northern Territory at Nitmiluk (Katherine Gorge) Nat. Park and Standley Chasm in the West MacDonnell Ranges.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Castes
Male and immature stages unknown.

Nomenclature

 *  archeri. Polyrhachis (Hagiomyrma) archeri Kohout, 2013: 531, figs. 6C-D (w.) AUSTRALIA.

Worker
(holotype cited first): TL c. 6.65, 6.55-6.96; HL 1.65, 1.62- 1.72; HW 1.31, 1.28-1.34; CI 79, 78-81; SL 1.93, 1.93-2.00; SI 147, 145-153; PW 1.23, 1.22-1.28; MW 0.72, 0.72-0.84; PMI 171, 149-171; MTL 2.03, 2.03-2.15 (8 measured).

Anterior clypeal margin medially with acutely denticulate flange. Clypeus with distinct median carina; straight in profile, posteriorly rounding into weakly impressed basal margin. Frontal carinae with weakly raised margins; central area relatively wide, flat. Sides of head in front of eyes converging towards mandibular bases in straight line; behind eyes, sides widely rounding into convex occipital margin. Eyes weakly convex, marginally exceeding lateral cephalic outline in full face view. Ocelli lacking. Pronotal dorsum distinctly wider than long, widest at about midlength; humeri widely rounded, with shallow depression dorsally along narrowly raised margins. Lateral margins of pronotum and mesonotum converging posteriorly. Metanotal groove indistinct. Propodeal margins terminating posteriorly in relatively short, acute spines; length of spines distinctly less than half distance between tips. Anterior face of petiole rounding dorsally into upturned, divergent, acute spines; bases of spines relatively close together, dorsum between them concave. Posterior face of petiole distinctly swollen. Anterior face of first gastral segment widely rounding onto dorsum.

Mandibles finely, longitudinally striate with numerous piliferous pits. Head, mesosoma and petiole finely and uniformly reticulate-punctate, opaque. Gaster shagreened.

Mandibular masticatory and outer borders with curved golden hairs and closely appressed shorter hairs towards bases. Anterior clypeal margin medially with a few, medium length setae. Several short and medium length, erect hairs on clypeus, along frontal carinae and on vertex; distinctly shorter and more sparse hairs on dorsum of mesosoma; gaster dorsally with numerous short, posteriorly inclined, pale golden hairs, hairs on gastral venter distinctly longer and more abundant. Silvery, appressed pubescence in various densities over most dorsal body surfaces, except gastral dorsum with golden and more abundant pubescence, completely hiding underlying sculpturation.

Black; mandibles, clypeus, frontal area, antennae and legs, including coxae, medium to dark reddish-brown. Mandibular teeth and anterior clypeal margin bordered with black.

Queen
TL c. 7.91-8.32; HL 1.72- 1.81; HW 1.37-1.40; CI 77-80; SL 1.87-1.93; SI 136-138; PW 1.62-1.68; MTL 1.96-2.15 (2 measured).

Apart from sexual characters very similar to worker except: mesoscutum wider than long with dorsum weakly convex in lateral view; median line distinct; parapsides flat. Mesoscutellum weakly convex, not elevated above dorsal plane of mesosoma. Propodeal spines very short, bases broad; petiolar spines shorter than in worker, distinctly obliquely elevated, divergent. Sculpturation, pilosity, pubescence and colour virtually identical to worker.

Type Material


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

Etymology
Named in honour of Prof. Michael Archer, formerly of the Queensland Museum, whose name is closely associated with the famous palaeontological site at Riversleigh which is near the type locality of the species.