Iridomyrmex elongatus, Heterick & Shattuck, 2011

Heterick, Brian E. & Shattuck, Steve, 2011, Revision of the ant genus Iridomyrmex (Hymenoptera: Formicidae) 2845, Zootaxa 2845 (1), pp. 1-174 : 79-80

Iridomyrmex elongatus sp. n.

( Figs 34 , 92 )

Types. Holotype worker from Kunoth Park near Alice Springs , Northern Territory, 3-6 February 1975, P. J. M. Greenslade, traps ( ANIC, ANIC32-032498 ) . Paratypes: 6 workers from 5mi. ENE Terhans Roadhouse , Western Australia, 15 October 1960, McInnes & Dowse ( ANIC, ANIC32-041281 , 3 workers; BMNH, ANIC32-041931 , 3 workers) ; 2 workers , 2 queens and 2 males from 37mi. SW Mundiwindi , Western Australia, 27 April 1963, McInnes & Dowse ( ANIC, ANIC32-041029 , 1 worker, 1 queen, 1 male; MCZC, ANIC32-041029 , 1 worker, 1 queen, 1 male) .

Worker Description. Head. Posterior margin of head strongly convex; erect setae on posterior margin in fullface view, present in small aggregations on one or both sides of posterior margin of head; sides of head straight or weakly convex; erect genal setae present on sides of head in full-face view. 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 convex; antennal scape surpassing posterior margin of head by at least 0.5 x its length. Erect setae on scape absent, except at tip; prominence on anteromedial clypeal margin always completely absent; 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 moderate in number (6-12), short and bristly. Mesonotum evenly curved. Erect mesonotal setae sparse to absent. Mesothoracic spiracles always inconspicuous; propodeal dorsum straight and short (equal in length to propodeal declivity); placement of propodeal spiracle mesad, more than its diameter away from propodeal declivity; propodeal angle present as a bluntly defined acute angle, the propodeal dorsum conical in shape. Erect propodeal setae moderate in number (6-12), short and bristly. Petiole. Dorsum of node 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 of foreparts tawny orange-brown, gaster and legs brown to dark brown. Colour of erect setae pale yellow.

Measurements. Worker (n = 3) — CI 80–82; EI 29–30; EL 0.24–0.25; EW 0.19–0.20; HFL 1.71–1.74; HL 1.02–1.03; HW 0.82–0.85; ML 1.60–1.64; MTL 1.17–1.20; PpH 0.18–0.22; PpL 0.61–0.62; SI 151–154; SL 1.26– 1.28.

Comments. The physical appearance of I. elongatus is suggestive of I. bicknelli , but the former is a brown ant and possesses erect setae on the hind tibiae (hind tibiae glabrous in I. bicknelli ). However, a convex posterior margin of the head is common to both ants, and that feature, along with the erect hind tibial setae, is sufficient to characterise I. elongatus . This species has been collected in well separated sites in Western Australia and the Northern Territory. Pitfall trapped material indicates that it is a terrestrial forager, but few samples have been collected and nothing more is known of its biology.

Etymology. Latin: reference is made to the gracile appearance of the ant.

Figures

FIGURE 34. Iridomyrmex elongatus (holotype, Alice Springs, NT, ANIC32-032498): A. Front of head; B. Side of body; C. Top of body; D. Distribution of material examined.

FIGURE 92. Scape length versus head width for I. anceps, I. curvifrons, I. elongatus, I. minor, I. rufoniger and I. suchieri.