Iridomyrmex suchieroides

This ant occurs throughout all mainland Australian states, but is absent from Tasmania. It can occur in sympatry with Iridomyrmex suchieri, even in the same back-yard (East Fremantle, Western Australia). The behaviour of both species is distinctly different. Whereas I. suchieri can be aggressive, challenging other ants (in the East Fremantle property mentioned above, I. suchieri workers confronted workers of Technomyrmex jocosus Forel hiding under capping on an asbestos fence), I. suchieroides forages furtively, running away timidly and hiding on human approach, and avoids contact with more aggressive species such as Iridomyrmex chasei. Iridomyrmex suchieroides has a small, unobtrusive nest hole. This species mainly forages on the ground but can climb in search of food: workers were collected in a malaise trap in Little Desert NP, Victoria.

Identification
Iridomyrmex suchieroides is likely to be the sister taxon of Iridomyrmex suchieri, and workers of both species are difficult to distinguish from one another. The diagnostic separators are described under I. suchieri. Iridomyrmex suchieroides has a very bristly appearance, with short, erect setae extending down the sides of the head capsule being clearly visible in full-face view.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  suchieroides. Iridomyrmex suchieroides Heterick & Shattuck, 2011: 146, fig. 77 (w.) AUSTRALIA.

Types
Holotype worker from Cambrai, South Australia, 2 1-29 February 1972, P. J. M. Greenslade (, ANIC32-037327). Paratypes: 2 workers, same data as holotype ; 1 worker from Cambrai, South Australia, 28 January 1972, P. J. M. Greenslade (, ANIC32-0373 18); 1 worker from Cambrai, South Australia, 25 February 1972, P. J. M. Greenslade (, ANIC32-03732 1); 2 workers from Cambrai, South Australia, 16-29 February 1972, P. J. M. Greenslade (, ANIC32-037320); 1 worker from Cambrai, South Australia, 28 January–1 February 1972, P. J. M. Greenslade (, ANIC32-037323).

Description
Worker Description. Head. Posterior margin of head 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 at about 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 1-2 x its diameter. Prominence on anteromedial clypeal margin projecting as blunt but distinct protuberance; mandible regularly 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, or straight. Erect mesonotal setae numerous (12 or more), short and bristly. Mesothoracic spiracles always inconspicuous; propodeal dorsum straight and short (equal in length to propodeal declivity); 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. Erect propodeal setae numerous (12 or more), short and bristly. Petiole. Dorsum of node convex; node thin, scale-like, 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 brown. Colour of erect setae whitish.

Measurements. Worker (n = 6)—CI 85–89; EI 27–29; EL 0.20–0.22; EW 0.16–0.18; HFL 0.85–1.01; HL 0.85–0.94; HW 0.72–0.81; ML 1.07–1.18; MTL 0.62–0.74; PpH 0.15–0.19; PpL 0.44–0.52; SI 99–104; SL 0.75– 0.83.

Etymology
Greek: ‘oides’ ‘like’ plus suchieri.

References based on Global Ant Biodiversity Informatics

 * Heterick B. E., and S. Shattuck. 2011. Revision of the ant genus Iridomyrmex (Hymenoptera: Formicidae). Zootaxa 2845: 1-174.