Iridomyrmex gumnos, Heterick & Shattuck, 2011

Heterick, Brian E. & Shattuck, Steve, 2011, Revision of the ant genus Iridomyrmex (Hymenoptera: Formicidae) 2845, Zootaxa 2845 (1), pp. 1-174 : 86

Iridomyrmex gumnos sp. n.

( Fig. 39 )

Types. Holotype worker from 50km S Olary, South Australia, 1977, Forrest ( ANIC, ANIC32-040581 ) . Paratypes: 1 worker, same data as holotype ( ANIC) ; 3 workers from Nymagee , New South Wales, 3 November 1964 ( ANIC, ANIC32-0040705 ) .

Worker Description. Head. Posterior margin of head weakly concave, or strongly 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, or absent; 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). In full-face view, eyes set at about 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 straight; antennal scape surpassing posterior margin of head by approximately 2 x its diameter. Erect setae on scape absent, except at tip; prominence on anteromedial clypeal margin always completely absent; mandible regularly triangular with oblique basal margin; long, curved setae on venter of head capsule absent. Mesosoma. Pronotum strongly inclined anteriorly. Erect pronotal setae lacking or very minute (one or two tiny setae may be present). 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 posteriad and near propodeal declivity; propodeal angle present as a bluntly defined right angle, the dorsal and declivitous propodeal faces never separated by a carina. 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 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 Light brown. Colour of erect setae pale, yellowish.

Measurements. Worker (n = 3)—CI 93–94; EI 26–27; EL 0.18–0.18; EW 0.14–0.15; HFL 0.78–0.80; HL 0.73–0.76; HW 0.68–0.70; ML 0.88–0.89; MTL 0.55–0.58; PpH 0.15–0.16; PpL 0.40–0.41; SI 95–99; SL 0.64– 0.69.

Comments. As with several other Iridomyrmex known only from one or two series, this taxon requires more material for a solid confirmation of its status as a bona fide species. The only known material is a single pin of two workers from 50 km S of Olary, South Australia, and one of three workers collected at Nymagee, New South Wales, 45 years ago. Apart from the characters used for a diagnosis—the absence of erect setae on the pronotum, the concave posterior margin of the head, the lack of iridescence on the gaster, and the antennal scape, which extends 2 × its diameter beyond the posterior margin of the head—the ant is unremarkable. In appearance, leaving aside the glabrous pronotum, the workers look pretty much like many workers of I. chasei or I. victorianus . Nothing is known about the ecology of the ant. The South Australian material was collected by PJM Greenslade in 1977. Nothing is known about how the three New South Wales workers were collected. Even the collector’s name is lacking.

Etymology. Latin: ‘nude’.

Figures

FIGURE 39. Iridomyrmex gumnos (paratype, Nymagee, NSW, ANIC32-040705): A. Front of head; B. Side of body; C. Top of body; D. Distribution of material examined.