Iridomyrmex rubriceps

Iridomyrmex rubriceps is an ant of the rainforest and wet sclerophyll forests of the Australian east coast. Various label data indicate that colonies of this species have been located under rocks or stones. Workers have also been taken from termite nests around logs in Castlereagh SF (New South Wales), and have been found foraging on low vegetation (Tamborine, Queensland) and tending lycaenid larvae (Jalmenus evagoras) (Maryborough, Queensland).

Identification
Iridomyrmex rubriceps is the sister species to Iridomyrmex agilis, and can be distinguished from it as described under that species.

Distribution
There is one South Australia record that requires verification.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  rubriceps. Iridomyrmex gracilis r. rubriceps Forel, 1902h: 468 (w.) AUSTRALIA. Raised to species: Heterick & Shattuck, 2011: 130.

Description
Worker Description. Head. Posterior margin of head weakly convex to planar; erect setae on posterior margin in full-face view set in a row; sides of head convergent anteriad; 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 semi-circular. Frontal carinae convex; antennal scape surpassing posterior margin of head by approximately 3 x its diameter. Erect setae on scape absent, except at tip; prominence on anteromedial clypeal margin projecting as triangular spur; 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 numerous (12 or more), short and bristly. Mesonotum straight. Erect mesonotal setae moderate in number (6–12), short and bristly. Mesothoracic spiracles always prominent as small, vertical protuberances; propodeal dorsum smoothly and evenly convex; placement of propodeal spiracle mesad, more than its diameter away from propodeal declivity; propodeal angle weakly present or absent, the confluence of the dorsal and declivitous propodeal faces indicated, if at all, by an undulation. Erect propodeal setae moderate in number (6–12), short and bristly. Petiole. Dorsum of node convex, or 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 head orange, pronotum brownish-orange, rest of body brown. Colour of erect setae pale, depigmented yellow.

Measurements. Worker (n = 3)—CI 81–82; EI 24–24; EL 0.29–0.29; EW 0.22–0.23; HFL 2.26–2.28; HL 1.47–1.5 1; HW 1.20–1.23; ML 2.00–2.06; MTL 1.58–1.63; PpH 0.23–0.24; PpL 0.72–0.74; SI 123–124; SL 1.49– 1.52.

References based on Global Ant Biodiversity Informatics

 * Forel A. 1915. Results of Dr. E. Mjöbergs Swedish Scientific Expeditions to Australia 1910-13. 2. Ameisen. Ark. Zool. 9(16): 1-119
 * Heterick B. E., and S. Shattuck. 2011. Revision of the ant genus Iridomyrmex (Hymenoptera: Formicidae). Zootaxa 2845: 1-174.