Leptanilla swani

Heterick (2009) - Described from a colony discovered at Goyamin Pool, near Chittering, approximately 75 km north of Perth. According to Shattuck (1999), workers have only been collected twice since that time. Males, however, have been collected more frequently, which suggests that current collecting techniques are not successfully sampling these tiny, exclusively subterranean ants. The Curtin Ant Collection holds two minute, male ants believed to be of this species, while males have also been collected in a Curtin project undertaken on Barrow Island. The sole SWBP specimen was collected on an Alcoa mine site in Jarrahdale. Nothing is known about the biology of this sole representative of the genus in Australian but a Japanese relative specialises on geophilomorph centipedes (Hölldobler and Wilson 1990).

Identification
Heterick (2009) - Workers in this subfamily may be confused with some very small, eyeless myrmicines, but the pronotum and mesonotum in Leptanilla are connected by a flexible hinge, and are not fused as they are in the Myrmicinae. Moreover, the antennal insertions are completely exposed in the former while they are at least partially covered in the latter.

Wheeler (1934) - L. swani seems to be most closely related to Leptanilla revelierii, but the female of the latter has a much shorter petiole. In the long pilosity of the gaster the female of the new form resembles Leptanilla theryi, but in this species the petiole is very different, being distinctly cordate anteriorly instead of oblong.

Distribution
Heterick (2009) - In Australia, known from NSW, QLD, SA and WA.

Distribution based on Regional Taxon Lists
Australasian Region: Australia. Indo-Australian Region: New Guinea.

Nomenclature

 *  swani. Leptanilla swani Wheeler, W.M. 1932b: 54, fig. 1 (w.q.) AUSTRALIA. Wheeler, G.C. & Wheeler, J. 1965: 30 (l.). See also: Baroni Urbani, 1977c: 457.

Worker
Length 1.3-1.5 mm. Pale yellow; legs scarcely paler than the body; teeth and borders of the mandibles reddish.

Head flattened above, oblong, fully 1 1/2 times as long as broad, as broad in front as behind, with subparallel sides, rounded posterior corners and feebly concave posterior border. Mandibles narrow, with very oblique 4-toothed apical borders, the terminal tooth curved and acute, the second minute, the two remaining teeth stout and rather blunt, the most basal directed at right angles to the apical border or even slightly backward. Clypeus without distinct posterior suture, its anterior border slightly but distinctly produced in the middle as a broadly rounded lobe, excised at the sides. Antennae moderately stout; scapes reaching nearly to the middle of the head; basal funicular joint nearly 11;2 times as long as broad, ovoidal, with constricted base; joints 2-6 distinctly broader than long; the second basally constricted, the seventh distinctly longer, 8-10 as broad as long, the terminal joint as long as the two preceding joints together. Thorax much narrower than the head including the mandibles, flattened dorsally and not deeply notched in profile at the promesonotal suture; pronotum subovoidal, somewhat broader than the mesepinotum, which is longer than the pronotum, with feebly rounded, subparallel sides. Petiole much narrower than the epinotum, nearly 1 1/2 times as long as broad, gradually narrowed anteriorly, posteriorly with rounded-subparallel sides. Postpetiole rounded-trapezoidal, nearly as long as broad, somewhat broader than the petiole and somewhat wider behind than in front, its ventral surface convex and projecting. Gaster narrow, elongate-elliptical, anterior border of first segment slightly concave. Sting large, retracted. Legs moderately stout, tips of fore metatarsi produced and digitiform, but not so narrowly as in Leptanilla nana.

Shining, with very fine and indistinct piligerous punctures. Pilosity white, very short, abundant both on the body and antennae, slightly longer and coarser on the gaster, less conspicuous and more dilute and appressed on the legs.

Queen
Length 2 mm.

Color, sculpture and pilosity as in the worker, but the hairs on the gaster very long, though fine, as in the female of Leptanilla theryi. Apterous and resembling the worker in form but differing in the following characters: Head more sharply oblong, with straight and more clearly parallel sides. Mandibles falcate, narrow and tapering at the tips, without distinct basal and apical borders, terminating in two small, indistinct, closely approximated teeth. Clypeus broader and less produced than in the worker. Thorax decidedly longer than the head plus the mandibles, very low and flat above, the pronotum posteriorly nearly as broad as the head, longer than broad, with feebly rounded, anteriorly converging sides, mesepinotum broader than the head, subtrapezoidal, broadest near the anterior end, roundly subtruncate behind. Promesonotal suture pronounced, straight and transverse in the middle. Petiole regularly oblong, about 1 1/4 longer than broad, as broad in front as behind. Gaster much larger than in the worker, the postpetiole, which forms its first segment, nearly twice as broad as long, subtrapezoidal, with straight anterior border. Genitalia similar to those of L. revelierei Emery, but the pygidium with entire, broadly and semicircularly rounded posterior border, not notched in the middle. Hypopygium large, narrowed and bluntly bidentate posteriorly. Legs longer and stouter than in the worker.

Type Material
Described from 24 workers and a single female taken Oct. 10, 1931 by Mr. D. C. Swan under a large stone at Goyamin Pool, Chittering, Western Australia.