Polyrhachis foreli

Polyrhachis foreli is a rainforest species commonly nesting in rotting logs, tree stumps and epiphytes or in the ground (Kohout 1989, 1998; Robson & Kohout 2005, 2007; Kohout 2012).

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

The distribution of P. foreli consists of two, substantially disjunct populations, Papuan and Australian. Apart from the specimens of the original series of ‘relucens decipiens papuana’ from the D’Entrecasteaux Islands, there is a relatively small number of additional specimens from the Papuan population, where the species appears fairly rare. On the other hand, in Australia (‘relucens andromache andromeda’) the species appears relatively common and ranges from Iron Range on Cape York Peninsula, throughout Queensland’s Wet Tropics to about Mission Beach and Hinchinbrook Island in the south (based on Kohout, 2012).

Castes
Males and immature stages are present in the ANIC spirit collection.

Nomenclature

 *  foreli. Polyrhachis foreli Kohout, 1989: 510, figs. 2, 7, 11 (w.q.) AUSTRALIA. Material of the unavailbale names andromeda, papuana referred here by Kohout, 1998: 521.

Holotype worker from near Clump Point, NE Tully, Queensland, 17°52’S, 146°07’E, 30.iv.1969 (R.W. Taylor acc. 69.123) (examined by Kohout, 2012).

Worker
Dimensions (holotype cited first): TL 8.62, 8.16 -9.37; HL 2.28, 2.21-2.46; HW 1.87, 1.75-1.96; CI 82, 78-82; SL 2.71, 2.59-2.90; SI 145,145-153; PW 1.59,1.50-1.75; MTL 2.84, 2.71-3.06 (25 measured).

Dimensions: TL 7.36-10.33; HL 1.96-2.46; HW 1.59-2.00; CI 78-82; SL 2.40-2.91; SI 145-153; PW 1.31-1.78; MTL 2.31-3.12 (25 measured).

Mandibles with 5 teeth, which reduce progressively in length towards the base. Clypeus in profile sinuate, convex above, shallowly concave below, the anterior margin somewhat obtusely truncated medially. Sides of head gently convex, converging anteriorly in front of eyes, and narrowly rounded behind the eyes into the weakly convex occipital margin. Eyes convex, situated well back on the head, usually not or only marginally breaking the cephalic outline. Frontal carinae with strongly raised lobes; area between them more than twice as wide behind than in the front. Pronotum with dorsum almost flat between a pair of long, horizontal, anteriorly directed, somewhat dorsomedially flattened spines. Outer borders of spines acute and continuous basally with the pronotal margins. Mesonotal dorsum wider than pronotum at the base, strongly transverse; lateral margins slightly raised, acute. Propodeum with narrowly rounded anterior angles, its sides converging posteriorly, terminating in more or less distinct, short, transverse tubercles, which are sometimes produced into small, posteriorly directed teeth. Declivity abrupt, concave in profile. Petiole in side view biconvex, armed with a pair of spines situated on the dorsolateral angles and separated by the transversely convex, more or less acute dorsal edge of the segment. A short, somewhat flattened, emarginated tooth on each side, situated laterally below the base of the adjanced spine. Base of first gastral tergite shallowly concave.

Mandibles towards the base finely, longitudinally striate, with numerous piliferous pits. Clypeus finely shagreened; anterior margin medially with a few distinct pits from which long hairs rise. Front of head shagreened; sculptural intensity more distinct laterally and posteriorly, with the dorsal face and lateral branches of occiput more or less longitudinally striate-punctate. Dorsum and sides of mesosoma fairly regularly longitudinally striate; sculptural intensity decreasing anteriorly and posteriorly, with the pronotal dorsum, spines, propodeal declivity, petiole and gaster shagreened.

Medium long, erect, silvery or golden hairs present in variable density on all body surfaces, but almost absent from the petiole and anterior face of the first gastral tergite. Leading edge of the antennal scapes occasionally with a few scattered short erect hairs. Relatively long, appressed, silvery to golden pubescence most dense on clypeus, frontal areas of head and the mesosomal dorsum.

Black throughout; only the appendages may sometimes be reddish-brown.

Queen
Dimensions: TL 10.23-11.44; HL 2.50-2.67; HW 1.96-2.14; CI 77-81; SL 2.87-3.06; SI 140-148; PW 2.21-2.37; MTL 3.06-3.22 (7 measured).

The female closely resembles the worker and, besides the usual characters identifying full sexuality, differs only in the following details: In full face view eyes clearly breaking the outline of head; pronotal spines much shorter, downturned; petiole with spines shorter, and the dorsal edge between them more or less medially emarginated.

Additional References

 * Kohout, R.J. 2012. A review of the Australian Polyrhachis ants of the subgenera Myrma Billberg, Myrmatopa Forel, Myrmothrinax Forel and Polyrhachis Fr. Smith (Hymenoptera: Formicidae: Formicinae). Memoirs of the Queensland Museum – Nature 56(1): 25-59.