Leptomyrmex mjobergi

L. mjobergi has been recorded in rainforest, open rainforest, wet sclerophyll and eucalyptus forest. Nests occur in the soil and under rocks.

Identification
This smallest macro-Leptomyrmex species can be readily identified by both size (HW 0.82–0.87 mm; WL 2.58–2.97 mm) and by the presence of a strongly inclined, scale-like petiole (all others are node-like). Workers of L. mjobergi are approximately half the size of the larger species in the genus (e.g. Leptomyrmex tibialis HW 1.68–1.96 mm), but remain larger than any of the micro-Leptomyrmex (HW < 0.80 mm). Leptomyrmex mjobergi occurs from Queensland’s northern Wet Tropics to the state’s southern border with New South Wales. Although it is unicolorous black, this nearly hairless species is unlikely to be confused with the other entirely black macro-Leptomyrmex in Australia, Leptomyrmex unicolor, which is distinctly pubescent, and quite large and stout (HW 1.37–1.51 mm; WL 3.27–3.73).

Key to Australian Leptomyrmex Species

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  mjobergi. Leptomyrmex mjobergi Forel, 1915b: 84 (w.) AUSTRALIA. Lucky & Ward, 2010: 39 (ergatoid q., m.).

Worker
Lucky and Ward (2010) – measurements (n = 10) HL 1.40–1.53, HW 0.82–0.87, MFC 0.15–0.18, IOD 0.46–0.51, SL 2.44–2.80, EL 0.33–0.38, WL 2.58–2.97, PW 0.75–0.85, DPW 0.29–0.33, HTL 2.17–3.30, HTWmin 0.09–0.14, HTWmax 0.17–0.21, CI 0.57–0.61, SI 2.85–3.34, OI 0.11–0.13, HTC 0.48–0.79.

Relatively small species (HW 0.82–0.87; WL 2.58–2.97). Head, excluding mandibles, nearly twice as long as broad (CI 0.57–0.61), with nearly straight and parallel sides. Postocular margin of head broadly rounded. Masticatory margin of mandible with approximately 20 small, mostly uniform teeth. Anterior clypeal margin convex. Eyes positioned approximately at the midline of the head; large, somewhat flattened to head, hairless and not surpassing lateral margins. Antennae lightly compressed, scape surpassing posterior margin of head by 3/5 of its length.

Pronotum approximately 1.5 times as long as broad, thorax distinctly laterally compressed. Propodeum abruptly raised from mesonotum; dorsal surface twice as long as declivity, dorsal face weakly convex. Petiole flattened and scale-like, strongly inclined forward, twice as high as long, rounded at apex, ventral surface feebly convex. Gaster elongate-elliptical.

Body surface finely shagreened, somewhat shining, with delicate short sparse pubescence throughout. Standing hairs sparse, confined to gaster, venter, clypeus and mandibles. Body black, mandibles reddish-brown, femora scapes and tibiae brown, tarsi reddish-yellow.

Queen
Lucky and Ward (2010) – Head broader than in worker. Three ocelli deeply set into head in triangular formation, the anteriormost one largest, the posterior two smaller. Pronotum, mesonotum and propodeum voluminous, convex. Petiole node-like and vertical, not scale-like or inclined forward, taller than broad, rounded dorsally. Gaster globose, larger than in worker. Scapes, femora and tibiae broad, distinctly robust. Surface of body appearing velvety, shagreened.

Male
Lucky and Ward (2010) – measurements (n = 4) HL 1.14–1.26, HW 0.84–0.95, SL 0.17–0.18, EL 0.53–0.64, HTL 2.72–2.90, CI 0.73–0.78, SI 0.19–0.20, SI2 0.53–0.65.