Iridomyrmex setoconus Shattuck & McMillan

(Fig. 71)

Iridomyrmex setoconus Shattuck & McMillan, 1998: 307, figs 9–11.

Types. Holotype worker from Yokinup Bay, Cape Arid Natl Pk [c. 33°52'S, 123°02'E], Western Australia (ANIC, ANIC32-023696, examined). Paratypes: same data as holotype (ANIC, ANIC32-000238, 45 workers, examined; BMNH, 3 workers; MCZC, 3 workers; WAMP, 3 workers).

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 fullface 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 0.2- 0.5 x its length. Erect setae on scape absent, except at tip; prominence on anteromedial clypeal margin present as an indistinct swelling or undulation; mandible elongate triangular with oblique basal margin; long, curved setae on venter of head capsule present. 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 inconspicuous; propodeal dorsum protuberant; placement of propodeal spiracle mesad, more than its diameter away from propodeal declivity; propodeal angle present as a bluntly defined acute angle, the propodeal dorsum conical in shape. Erect propodeal setae numerous (12 or more), short and bristly. Petiole. Dorsum of node convex; node thick, orientation more-or-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 reddish-brown, legs and gaster dark brown. Colour of erect setae medium brown.

Measurements. Worker (n = 5) — CI 94–100; EI 22–23; EL 0.24–0.27; EW 0.15–0.17; HL 1.10–1.17; HW 1.04–1.17; ML 0.52–0.61; PpH 0.27–0.32; PpL 0.60–0.70; SI 99–108; SL 1.12–1.16.

Comments. Iridomyrmex setoconus is restricted to two small populations at Yokinup Bay and Thomas River, respectively. Both localities are east of Esperance. This species is easily recognised by virtue of the short, straight or only weakly curved erect setae on the sides of the head capsule (longer and strongly curved in those workers of I. turbineus that possess such pilosity). Iridomyrmex setoconus has only been collected on calcareous or otherwise sandy soils, and may require such a substrate for its nests. Nothing more is known of its ecology (see Shattuck & McMillan, 1998).