Iridomyrmex agilis Forel

Heterick, Brian E. & Shattuck, Steve, 2011, Revision of the ant genus Iridomyrmex (Hymenoptera: Formicidae) 2845, Zootaxa 2845 (1), pp. 1-174 : 37

Iridomyrmex agilis Forel

( Fig. 8 )

Iridomyrmex agilis Forel, 1907a: 295 .

Types. Syntypes from Yalgoo , Western Australia ( ANIC, 1 worker (missing petiole and gaster), examined; MCZC, 1 worker (missing petiole and gaster), examined; MHNG, 2 workers (1 missing petiole and gaster); WAMP, 1 worker (missing petiole and gaster), examined) .

Worker Description. Head. Posterior margin of head strongly convex; erect setae on posterior margin in fullface view set in a row; sides of head convergent anteriad; erect genal setae present on sides of head in full-face view, or 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 straight; antennal scape surpassing posterior margin of head by 0.2-0.5 x its length. 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 sinuous. Erect mesonotal setae moderate in number (6-12), short and bristly. Mesothoracic spiracles prominent or inconspicuous; propodeal dorsum smoothly and evenly convex; placement of propodeal spiracle posteriad and near propodeal declivity, or 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 thin, scale-like, orientation more-or-less vertical, or 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, or absent on first tergite. General characters. Allometric differences between workers of same nest absent. Colour of foreparts variable, from light-yellow-orange to dark purple with iridescence ranging from very pale pink or yellowish to blue, legs brown with weak bluish iridescence, gaster dark brown. Colour of erect setae pale, whitish.

Measurements. Worker (n = 5)—CI 78–81; EI 24–26; EL 0.31–0.34; EW 0.25–0.27; HFL 2.44–2.93; HL 1.56–1.70; HW 1.26–1.33; ML 2.11–2.31; MTL 1.72–2.20; PpH 0.22–0.25; PpL 0.79–0.86; SI 118–137; SL 1.55– 1.75.

Comments. Iridomyrmex agilis can be distinguished from most other Iridomyrmex species by its elongate form, long head, which, in full-face view, is broader at and just above the eyes, and the distinctive, spur-like anteromedial clypeal prominence. Its near relative, I. rubriceps , can be separated from I. agilis by the contrasting colour of its head and pronotum compared with its mesonotum and propodeum (the former parts are of uniform colouration with the rest of the mesosoma in I. agilis ). Iridomyrmex bicknelli is also similar, but has a slightly differently shaped head, and the hind femora are shorter in relation to the mesosoma. Iridomyrmex agilis is typically found in drier regions, where workers forage singly along well defined but indistinct paths across the ground, scurrying quickly with their gasters raised.

Figures

FIGURE 8. Iridomyrmex agilis, typical form (Murray Sunset National Park, Vic., ANIC32-043285): A. Front of head; B. Side of body; C. Top of body. Iridomyrmex agilis, dark form (Cowangie, Vic., ANIC32-038651): D. Front of head; E. Side of body; F. Top of body; G. Distribution of material examined.