Iridomyrmex spadius Shattuck

Heterick, Brian E. & Shattuck, Steve, 2011, Revision of the ant genus Iridomyrmex (Hymenoptera: Formicidae) 2845, Zootaxa 2845 (1), pp. 1-174 : 138

Iridomyrmex spadius Shattuck

( Fig. 72 )

Iridomyrmex spadius Shattuck, 1993a: 138 , figs 7, 17.

Types. Holotype worker from Millstream National Park, near Ravenshoe , Queensland ( ANIC, ANIC32-017915 , examined) . Paratypes: same data as holotype ( ANIC, ANIC32-009157 , 6 workers, examined; ANIC, ANIC32- 009156 , 2 workers, examined; ANIC, ANIC32-009158 , 2 workers, examined; BMNH, 3 workers; MCZC, 3 workers) .

Worker Description. Head. Posterior margin of head weakly concave; erect setae on posterior margin in fullface 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 semi-circular. Frontal carinae convex; antennal scape surpassing posterior margin of head by approximately 3 x its diameter. Erect setae on scape present and abundant; 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 moderately and evenly curved over its length. Erect pronotal setae numerous (12 or more), short and bristly. Mesonotum sinuous. 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 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 acuminate; 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 head orange with weak green iridescence, mesosoma and legs brown (mesosoma with pink iridescence), gaster chocolate with bluish iridescence. Colour of erect setae brown.

Measurements. Worker (n = 13) — CI 89–95; EI 18–21; EL 0.34–0.38; EW 0.20–0.23; HL 1.83–2.11; HW 1.66–1.99; ML 0.89–1.07; PpH 0.25–0.33; PpL 0.95–1.10; SI 91–105; SL 1.64–1.81.

Comments. Iridomyrmex spadius belongs to the I. purpureus complex, but can be distinguished from other members of the complex by its light yellow-red head, contrasting with the darker mesosoma. This is a localised species, known only from two disjunct populations in north-eastern and eastern Queensland, respectively. Ecological information is lacking. Shattuck (1993a) found that the male genitalia for this taxon were distinctive within the I. purpureus species-group.

Figures

FIGURE 72. Iridomyrmex spadius (holotype, Millstream National Park, Qld, ANIC32-017915): A. Front of head; B. Side of body; C. Top of body; D. Distribution of material examined (A. Noble, www.antweb.org).