Iridomyrmex infuscus

This species is so far known from a single collection made using a pitfall trap in a forested area of the ACT.

Identification
Despite the fact that I. infuscus is known from the holotype only, it cannot be mistaken for any of its close relatives. The straight frontal carinae separate it from similar species that lack iridescence and have a hairy mesosoma and erect setae on the hind tibiae.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  infuscus. Iridomyrmex infuscus Heterick & Shattuck, 2011: 91, fig. 43 (w.) AUSTRALIA.

Description
Worker Description. Head. Posterior margin of head planar to weakly concave; erect setae on posterior margin absent; sides of head noticeably convex. Ocelli absent; in full-face view, eyes set at about midpoint of head capsule; in profile, eye set anteriad of head capsule; eye elongate. Frontal carinae straight; antennal scape barely attaining posterior margin of head, or surpassing it by less than 1 x its diameter. Erect setae on scape absent, except at tip; prominence on anteromedial clypeal margin always completely absent; mandible regularly 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 straight. Erect mesonotal setae numerous (12 or more), short and bristly. Mesothoracic spiracles always prominent as small, vertical protuberances; propodeal dorsum protuberant; placement of propodeal spiracle 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 planar; node thin, scale-like, orientated anteriad. 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 most of head, mesonotum, propodeum, node, gaster chocolate, lateral clypeus, lower genae and pronotum infuscated reddish-orange. Colour of erect setae whitish.

Measurements. Worker (n = 1)—CI 95; EI 25; EL 0.28; EW 0.22; HFL 1.19; HL 1.15; HW 1.10; ML 1.50; MTL 0.83; PpH 0.25; PpL 0.62; SI 81; SL 0.89.

Etymology
Latin: ‘infuscus’—‘dark brown’ or ‘blackish’.

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.