Iridomyrmex xanthocoxa, Heterick & Shattuck, 2011

Heterick, Brian E. & Shattuck, Steve, 2011, Revision of the ant genus Iridomyrmex (Hymenoptera: Formicidae) 2845, Zootaxa 2845 (1), pp. 1-174 : 158-159

Iridomyrmex xanthocoxa sp. n.

( Fig. 85 )

Types. Holotype worker from 13km ENE Millstream , Western Australia, 29 October 1970, J. Cardale, ANIC Ants Vial 9.92 ( ANIC, ANIC32-039676 ) . Paratypes: 8 workers, same data as holotype ( ANIC, 5 workers; MCZC, 3 workers) ; 3 workers from 3.2km SSE Dampier , Western Australia, 18 October 1970, J. Feehan ( BMNH, ANIC32- 039677 ) .

Worker Description. Head. Posterior margin of head weakly concave, or strongly concave; erect setae 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 fullface view, eyes set above midpoint of head capsule; in profile, eye set anteriad of head capsule; eye semi-circular, or asymmetrical, curvature of inner eye margin more pronounced than that of its outer margin. 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 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 sparse (6 or fewer) and bristly. Mesonotum evenly curved. Erect mesonotal setae sparse (6 or fewer) and bristly. Mesothoracic spiracles prominent or inconspicuous; 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; 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, mesosoma and fore coxae orange or reddish-orange, legs and gaster brown, gaster with bluish iridescence.

Measurements. Worker (n = 4) — CI 64–70; EI 40–42; EL 0.25–0.28; EW 0.20–0.21; HFL 1.46–1.74; HL 0.90–1.03; HW 0.60–0.66; ML 1.25–1.39; MTL 1.06–1.22; PpH 0.13–0.15; PpL 0.47–0.53; SI 154–175; SL 1.00– 1.15.

Comments. Iridomyrmex xanthocoxa is very similar to red or reddish variants of I. minor , but the yellowishorange fore coxa (the same colour as the mesosoma) is diagnostic of the species throughout its relatively restricted range. The antennal scape, hind tibia and sides of the head lack erect setae. This species is confined to the Pilbara region of Western Australia, but can be quite abundant in pitfall samples from certain areas. Label data are sadly lacking in behavioural or ecological detail, but the biology of the ant may be expected to be similar to that of I. minor , to which it is very likely closely related.

Etymology. Greek: ‘ xanthos ’—‘yellow’ plus ‘ coxa ’, referring to the orange-yellow coxae found in this species.

Figures

FIGURE 85. Iridomyrmex xanthocoxa (Millstream, WA, ANIC32-039675): A. Front of head; B. Side of body; C. Top of body; D. Distribution of material examined.