Iridomyrmex mattiroloi

Iridomyrmex mattiroloi, a Tasmanian endemic, is known to nest under rocks. Most collections have been made sweeping low vegetation (including Leptospermum, Euchryphia and Allocasuarina) and by pitfall trapping.

Identification
This species is very similar to Iridomyrmex splendens, but can be distinguished from that species by its much shorter antennal scape and more truncate propodeum. Iridomyrmex meridianus is another, similar species that also occurs in Tasmania. However, I. meridianus has a glabrous or nearly glabrous mesosoma, whereas I. mattiroloi possesses numerous bristly, erect, mesosomal setae.

Identification Keys including this Taxon

 * Key to Iridomyrmex species

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  mattiroloi. Iridomyrmex mattiroloi Emery, 1898b: 236, fig. 8 (w.) AUSTRALIA (Tasmania). Crozier, 1969: 249 (k.). See also: Heterick & Shattuck, 2011: 100.

Description
Worker Description. Head. Posterior margin of head strongly concave; erect setae on posterior margin on posterior margin in full-face view set in a row; sides of head noticeably convex; erect genal setae absent from sides of head in full-face view (one to a few small setae may be present near mandibular insertion). Ocelli absent; in full- face view, eyes set at about midpoint of head capsule; in profile, eye set anteriad of head capsule; eye asymmetrical, curvature of inner eye margin more pronounced than that of its outer margin. Frontal carinae convex; 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 present as an indistinct swelling or undulation; 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 moderate in number (6– 12), short and bristly. Mesonotum evenly curved. Erect mesonotal setae moderate in number (6– 12), short and bristly. Mesothoracic spiracles always inconspicuous; propodeal dorsum smoothly and evenly convex, or straight and short (equal in length to propodeal declivity); placement of propodeal spiracle posteriad and near 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 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 to reddish-black, with faint blue iridescence on gaster. Colour of erect setae pale yellowish to whitish.

Measurements. Worker (n = 4)—CI 86–89; EI 26–27; EL 0.18–0.20; EW 0.14–0.15; HFL 0.83–0.87; HL 0.80–0.84; HW 0.69–0.75; ML 0.93–1.03; MTL 0.60–0.63; PpH 0.15–0.16; PpL 0.41–0.45; SI 89–96; SL 0.66– 0.69.