Iridomyrmex luteoclypeatus, Heterick & Shattuck, 2011

Heterick, Brian E. & Shattuck, Steve, 2011, Revision of the ant genus Iridomyrmex (Hymenoptera: Formicidae) 2845, Zootaxa 2845 (1), pp. 1-174 : 97-99

Iridomyrmex luteoclypeatus sp. n.

( Fig. 47 )

Types. Holotype worker from Cooper Ck. 13km NEbyN Etadunna Homestead , South Australia, 28°38’S 138°42’E, 16 September 1972, J. Feehan, ANIC Ants Vial 15.165 ( ANIC, ANIC32-038975 ) . Paratypes: 1 worker, same data as holotype ( ANIC) ; 4 workers from 1km W Emu Camp, Victoria Desert , South Australia, 6 October 1976, P. J. M. Greenslade ( ANIC, ANIC32-038991 , 2 workers; ANIC, ANIC32-038992 , 2 workers) ; 1 worker from Emu Camp, Victoria Desert , South Australia, 5 October 1976, P. J. M. Greenslade ( MCZC, ANIC32- 038979 ) ; 1 worker from Emu Camp, Victoria Desert , South Australia, 7 October 1976, P. J. M. Greenslade ( BMNH, ANIC32-038989 ) .

Worker Description. Head. Posterior margin of head weakly convex to planar; erect setae on posterior margin in full-face view, present in small aggregations on one or both sides of posterior margin of head, or in full-face view, present singly or as a couple of setae on either side of posterior margin of head; sides of head noticeably convex, or straight or weakly 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 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 concave, or 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 blunt but distinct protuberance; 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 sparse (6 or fewer) and bristly. Mesonotum evenly curved. Erect mesonotal setae sparse (6 or fewer) and bristly. Mesothoracic spiracles always inconspicuous; propodeal dorsum straight and long (half as long again as length of propodeal declivity); 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 sparse (6 or fewer) and bristly. Petiole. Dorsum of node convex; node thin, scale-like, orientation more-or-less vertical. Gaster. Non-marginal erect setae of gaster present or absent 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 mandibles and lower clypeal region yellow, legs pale brown, rest of ant medium to dark brown with pale bluish to purple iridescence. Colour of erect setae yellow.

Measurements. Worker (n = 4) — CI 79–82; EI 34–35; EL 0.24–0.26; EW 0.18–0.19; HFL 1.31–1.38; HL 0.87–0.92; HW 0.72–0.74; ML 1.18–1.26; MTL 0.95–0.99; PpH 0.14–0.16; PpL 0.47–0.51; SI 124–129; SL 0.89– 0.95.

Comments. Workers of I. luteoclypeatus are very similar to those of I. bicknelli , and collection material has certainly been confused with that species in the past. Nonetheless, the two species can be distinguished by dint of the appearance of the posterior margin of the head (weakly to strongly convex in I. bicknelli , planar in I. luteoclypeatus ) and the sides of the head when the ant is seen in full-face view (convergent towards the mandibles in I. bicknelli and parallel or weakly convex in I. luteoclypeatus ). Iridomyrmex luteoclypeatus workers are also a dull brown, whereas those of I. bicknelli are generally very dark brown or black with bluish to yellowish-green iridescence. This species is generally distributed in the dry centre of Australia from extreme north-eastern Western Australia to extreme western Queensland and south throughout South Australia, and has recently been identified from a worker collected in a sand dune in Carnarvon on the mid-west coast in Western Australia. Thus far, no samples have been taken in New South Wales, Victoria or Tasmania. The ant forages diurnally, but nothing else is known about it.

Etymology. Latin: ‘ luteus ’ ‘yellow’ plus ‘ clypeatus ’ ‘shield-shaped’; referring to the large yellow sectors on the clypeus in typical workers of this species.

Figures

FIGURE 47. Iridomyrmex luteoclypeatus (Clifton Hills, SA, ANIC32-038995): A. Front of head; B. Side of body; C. Top of body; D. Distribution of material examined.