Iridomyrmex reburrus

Iridomyrmex reburrus shows a preference for riparian habitats (Andersen, 2000), and was recently found to be particularly common near the Darwin (Northern Territory) International Airport, along the banks of Rapid Creek. Interestingly, isolated collections of I. reburrus have also been made in remote mallee country in south-eastern Western Australia (Emu Rock and Gora Hill), these colonies being well separated from other known populations (see Heterick, 2009).

Identification
In contrast with Iridomyrmex purpureus and its relatives, I. reburrus belongs to a largely northern meat ant complex in which the posterior pronotum rises rather abruptly towards its junction with the mesonotum (the posterior pronotum has a much more gradual slope in the I. purpureus complex). While I. reburrus workers can generally be distinguished by the erect setae on the sides of the head, this condition can also occur in the closely related Iridomyrmex sanguineus, so it is desirable, if possible, to examine a series of ants (in the case of I. sanguineus, individuals without erect setae on the sides of the head are much more frequent than those possessing them, whereas all I. reburrus workers possess at least 2–4 erect setae and commonly 15–40 such setae: see Shattuck (1993 a) for a fuller discussion of this feature). Living or freshly collected workers of I. reburrus also tend to be somewhat darker than I. sanguineus workers (Shattuck, 1993a).

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  reburrus. Iridomyrmex reburrus Shattuck, 1993a: 132, figs. 8, 14 (w.) AUSTRALIA. See also: Heterick & Shattuck, 2011: 127.

Description
Worker Description. Head. Posterior margin of head planar to weakly concave; erect setae on posterior margin in full-face view set in a row; sides of head noticeably convex; erect genal setae present on sides of head in full- face view. Ocelli absent; in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of head capsule; eye semi-circular. Frontal carinae convex; antennal scape surpassing posterior margin of head by 1–2 x its diameter. Erect setae on scape present and abundant; prominence on anteromedial clypeal margin projecting as triangular spur; mandible elongate triangular with oblique basal margin; long, curved setae on venter of head capsule absent. Mesosoma. Pronotum moderately and evenly curved over its length. Erect pronotal setae numerous (12 or more), short and bristly. Mesonotum sinuous. Erect mesonotal setae numerous (12 or more), short and bristly. Mesothoracic spiracles always prominent as small, vertical protuberances; propodeal dorsum protuberant, or smoothly and evenly convex; placement of propodeal spiracle posteriad and near propodeal declivity, or mesad, more than its diameter away from propodeal declivity; propodeal angle present as a bluntly defined right angle, the dorsal and declivitous propodeal faces never separated by a carina, or weakly present or absent, the confluence of the dorsal and declivitous propodeal faces indicated, if at all, by an undulation. Erect propodeal setae numerous (12 or more), short and bristly. Petiole. Dorsum of node acuminate, or convex; node thin, scale-like, orientation moreor-less vertical. Gaster. Non-marginal erect setae of gaster present on first gastral tergite; marginal erect setae of gaster present on first tergite. General characters. Allometric differences between workers of same nest absent. Colour foreparts orange to reddish, gaster dark brown to black, legs brown, iridescence on body and legs (where present) pinkish, iridescence on gaster yellow-green to bluish. Colour of erect setae brown to dark brown.

Measurements. Worker (n = 31)—CI 86–95; EI 17–21; EL 0.26–0.36; EW 0.16–0.23; HL 1.46–2.09; HW 1.26–1.99; ML 0.64–1.06; PpH 0.19–0.32; PpL 0.69–1.06; SI 89–108; SL 1.36–1.82.