Iridomyrmex elongatus

This species has been collected in well separated sites in Western Australia and the Northern Territory. Pitfall trapped material indicates that it is a terrestrial forager, but few samples have been collected and nothing more is known of its biology.

Identification
The physical appearance of I. elongatus is suggestive of Iridomyrmex bicknelli, but the former is a brown ant and possesses erect setae on the hind tibiae (hind tibiae glabrous in I. bicknelli). However, a convex posterior margin of the head is common to both ants, and that feature, along with the erect hind tibial setae, is sufficient to characterise I. elongatus.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  elongatus. Iridomyrmex elongatus Heterick & Shattuck, 2011: 79, figs. 34, 92 (w.) AUSTRALIA.

Description
Worker Description. Head. Posterior margin of head strongly convex; erect setae on posterior margin in full- face view, present in small aggregations on one or both sides of posterior margin of head; sides of head straight or weakly 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, or asymmetrical, curvature of inner eye margin more pronounced than that of its outer margin. Frontal carinae convex; antennal scape surpassing posterior margin of head by at least 0.5 x its length. Erect setae on scape absent, except at tip; prominence on anteromedial clypeal margin always completely absent; mandible elongate triangular with oblique basal margin; long, curved setae on venter of head capsule absent. Mesosoma. Pronotum weakly undulant or almost straight. Erect pronotal setae moderate in number (6-12), short and bristly. Mesonotum evenly curved. Erect mesonotal setae sparse to absent. Mesothoracic spiracles always inconspicuous; propodeal dorsum straight and short (equal in length to propodeal declivity); 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 moderate in number (6-12), short and bristly. Petiole. Dorsum of node planar; 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 of foreparts tawny orange-brown, gaster and legs brown to dark brown. Colour of erect setae pale yellow.

Measurements. Worker (n = 3)—CI 80–82; EI 29–30; EL 0.24–0.25; EW 0.19–0.20; HFL 1.71–1.74; HL 1.02–1.03; HW 0.82–0.85; ML 1.60–1.64; MTL 1.17–1.20; PpH 0.18–0.22; PpL 0.61–0.62; SI 151–154; SL 1.26– 1.28.

Etymology
Latin: reference is made to the gracile appearance of the ant.