Iridomyrmex neocaledonica, Heterick & Shattuck, 2011

Heterick, Brian E. & Shattuck, Steve, 2011, Revision of the ant genus Iridomyrmex (Hymenoptera: Formicidae) 2845, Zootaxa 2845 (1), pp. 1-174 : 111-112

Iridomyrmex neocaledonica sp. n.

( Figs 55 , 96 )

Types. Holotype worker from Mt Mou summit, New Caledonia, 22°04’S 166°21’E, 1200 m, 24 May 1984, G. Monteith & D. Cook, rainforest, moss on trees and rocks ( ANIC, ANIC32-041436 ) . Paratypes: 6 workers from Montagne des Sources , New Caledonia, 22°08’S 166°36’E, 27 February 1977, P. Ward, ANIC Ants Vial 64.17 ( ANIC, MCZC, 3 each, ANIC32-040305 ) .

Worker Description. Head. Posterior margin of head planar to weakly concave; erect setae on posterior margin 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; 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 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 present as an indistinct swelling or undulation; 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 sparse (6 or fewer) and bristly. Mesonotum sinuous, or evenly curved. Erect mesonotal setae sparse (6 or fewer) and bristly. Mesothoracic spiracles always inconspicuous; propodeal dorsum smoothly and evenly convex; placement of propodeal spiracle posteriad and near 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 lacking or very minute (one or two tiny setae present). 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 absent on first tergite. General characters. Allometric differences between workers of same nest absent. Colour uniformly pale to dark brown. Colour of erect setae depigmented, pale.

Measurements. Worker (n = 3)—CI 85–86; EI 26–27; EL 0.21–0.22; EW 0.16–0.17; HFL 1.16–1.25; HL 0.95–0.98; HW 0.82–0.84; ML 1.23–1.27; MTL 0.82–0.86; PpH 0.16–0.17; PpL 0.51–0.52; SI 115–116; SL 0.94– 0.96.

Comments. Apart from its biogeography, this handsome medium-sized, brown Iridomyrmex is distinguished from very similar species like I. splendens , I. meridianus and I. mjobergi (southern, mesic populations) by a combination of its longer antennal scape (extending beyond the posterior margin of the head by 3 × its greatest width) and lack of a row of setae on the posterior margin of the head. The handful of specimens available has been collected at a considerable elevation on the island (to 1200 m).

Etymology. Latin: with reference to the distribution of the species ( New Caledonia).

Figures

FIGURE 55. Iridomyrmex neocaledonica (paratype, Montagne des Sources, New Caledonia, ANIC32-040305): A. Front of head; B. Side of body; C. Top of body; D. Distribution of material examined.

FIGURE 96. Scape length versus head width for I. meridianus, I. mjobergi, I. neocaledonica, I. splendens and I. victorianus.