Polyrhachis crawleyi

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Polyrhachis crawleyi
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Camponotini
Genus: Polyrhachis
Subgenus: Hagiomyrma
Species group: penelope
Species: P. crawleyi
Binomial name
Polyrhachis crawleyi
Forel, 1916

Polyrhachis crawleyi casent0906588 p 1 high.jpg

Polyrhachis crawleyi casent0906588 d 1 high.jpg

Specimen Labels

Polyrhachis crawleyi is uncommon with a rather patchy distribution across northern Australia. It is apparently restricted to open eucalypt forests and savannah woodlands, preferring patches of bare ground without a covering of grass to excavate their ground-based nests.

Identification

A member of the penelope species-group in the Polyrhachis subgenus Hagiomyrma. Kohout (1988): Similar to Polyrhachis ammonoeides. P. crawleyi is smaller (HL < 1.80), has longer antennal scapes (SI > 155) and the body is covered by very fine, somewhat dilute silvery pubescence. P. ammonoeides is always larger (HL > 1.90), with much shorter antennal scapes (SI < 148), a generally more glossy appearance, and with pubescence virtually absent from all body surfaces except the gaster. The widely divergent propodeal spines are almost straight in P. crawleyi, while in P. ammonoeides their tips are distinctly turned outwards.

Kohout (2013): Polyrhachis crawleyi is rather similar to Polyrhachis cracenta, but is separable by its consistently smaller size and closely reticulate-punctate sculpturation of the body, with distinguishing characters provided in the remarks of the latter species.

Keys including this Species

Distribution

Found in North Queensland and the Northern Territory. It is known from Lakefield on Cape York Peninsula south to Rockhampton, areas to the south of the Gulf of Carpentaria, and the Darwin district (Kohout 1988).

Distribution based on Regional Taxon Lists

Australasian Region: Australia (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Castes

Male and immature stages were reported in F.P. Dodd’s collection, however, their location is unknown and the material is probably lost.

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • crawleyi. Polyrhachis (Hagiomyrma) ammonoeides var. crawleyi Forel, 1916: 447 (w.) AUSTRALIA. Raised to species: Kohout, 1988c: 433.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

(syntypes cited first): TL c. 6.20-6.60, 6.65-8.01; HL 1.53 1.69, 1.53-1.90; HW 1.25-1.31, 1.25-1.47; CI 77 82, 76-82; SL 1.93 2.12, 1.93-2.34; SI 154 162, 154-170; PW 0.87-0.91, 0.87-1.06; MW 0.59, 0.59- 0.69; PMI 147, 147-164; MTL 2.25 2.47, 2.25-2.75; (3+25 measured).

Anterior clypeal margin medially with shallow, truncate, denticulate flange, flanked by blunt teeth. Clypeus with distinctly raised median carina; sinuate in profile with moderately impressed basal margin. Frontal triangle poorly indicated. Frontal carinae sinuate with moderately raised margins; central area relatively wide with rather flat frontal furrow. Sides of head in front of eyes converging towards mandibular bases in almost straight line; behind eyes, sides rounding into convex occipital margin. Eyes convex, in full face view clearly breaking lateral cephalic outline. Ocelli lacking. Pronotal humeri dilated, distinctly rounded with weakly raised margins; dorsum with lateral margins distinctly emarginate or notched at about midlength, subparallel or weakly diverging towards promesonotal suture. Lateral margins of mesonotum converging posteriorly and weakly raised towards laterally impressed, medially flat metanotal groove. Propodeal dorsum with margins terminating in broad-based, long, slender, widely divergent, acute spines. Anterior face of petiole in side view rounding dorsally into long, slender, widely divergent spines, dorsum between spines deeply concave. Base of first gastral segment widely rounding onto dorsum.

Mandibles longitudinally striate with numerous piliferous pits. Head and mesosoma closely reticulate-punctate; spines sculptured for most of length, tips smooth. Gaster finely shagreened.

Mandibles with numerous medium length, golden hairs at masticatory borders; distinctly shorter and closely appressed hairs towards mandibular bases. Only a few anteriorly directed setae fringing anterior clypeal margin. Several paired, medium length hairs on clypeus, along frontal carinae and vertex. Somewhat longer, variously inclined hairs on dorsum of mesosoma and fore coxae; distinctly shorter hairs on venter of mid and hind coxae and femora. Gaster with numerous, posteriorly directed golden hairs, rather short on dorsum, distinctly longer and more abundant on venter and around apex. Closely appressed, somewhat medially radiating golden pubescence with somewhat brassy hue, over most dorsal body surfaces, including dorsum of gaster, where it is rather abundant, completely hiding underlying sculpturation; pubescence more sporadic and mostly silvery on sides of head, mesosoma and venter of gaster.

Black; mandibular teeth and appendages usually very dark reddish-brown.

Queen

TL c. 9.83; HL 2.03; HW 1.57; CI 77; SL 2.15; SI 137; PW 1.81; MTL 2.82 (1 measured).

Apart from sexual characters very similar to worker, except: pronotal dorsum with humeri subacute, margins widely rounded behind. Mesoscutum marginally wider than long; median line distinct, bifurcate anteriorly; parapsides flat anteriorly, weakly raised posteriorly; anterior margin of mesoscutum evenly rounded; dorsum relatively low and very weakly convex in lateral view; mesoscutellum only weakly elevated above dorsal plane of mesoscutum. Propodeal and petiolar spines similar to those in worker, but distinctly shorter. Sculpturation, pilosity, pubescence and colour virtually identical to worker.

Type Material

  • Polyrhachis (Hagiomyrma) ammonoeides crawleyi Forel, 1916: Syntype, worker(s), northern Australia, Australia, Musee d'Histoire Naturelle Genève.
  • Polyrhachis (Hagiomyrma) ammonoeides crawleyi Forel, 1916: Syntype, worker(s), northern Australia, Australia, Queensland Museum.

References

  • Forel, A. 1916. Fourmis du Congo et d'autres provenances récoltées par MM. Hermann Kohl, Luja, Mayné, etc. Rev. Suisse Zool. 24: 397-460 (page 447, worker described)
  • Kohout, R. J. 1988c. Nomenclatural changes and new Australian records in the ant genus Polyrhachis Fr. Smith (Hymenoptera: Formicidae: Formicinae). Mem. Qld. Mus. 25: 429-438 (page 433, Raised to species)
  • Kohout, R.J. 2013. Revision of Polyrhachis (Hagiomyrma) Wheeler, 1911 (Insecta: Hymenoptera: Formicidae: Formicinae). Memoirs of the Queensland Museum, Nature 56, 487-577.