Leptomyrmex ruficeps

Leptomyrmex ruficeps has been recorded mostly in rainforest, with one record from Eucalyptus open forest. Nests occur in cavities in live trees, on the ground at tree bases, in or under logs, and under rocks.

Identification
This species is restricted to the Australian Wet Tropics, where it can be easily distinguished from its sympatric congeners (Leptomyrmex rufipes, Leptomyrmex unicolor and Leptomyrmex mjobergi) by the neck-like constriction of the posterior margin of the head, and its distinctive coloration: black body with red head and antennae. This species is more slender than L. unicolor and larger than L. mjobergi. With the exception of coloration, this species closely resembles its sister species, L. rufipes, which is red with a black gaster. (Lucky and Ward 2010)

Identification Keys including this Taxon

 * Key to Australian Leptomyrmex Species

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Castes
Queens have yet to be collected.

Nomenclature

 *  ruficeps. Leptomyrmex varians var. ruficeps Emery, 1895g: 352 (w.) AUSTRALIA. Forel, 1915b: 84 (m.); Wheeler, W.M. 1915d: 261 (l.). Subspecies of varians: Wheeler, W.M. 1934c: 102. Raised to species: Lucky & Ward, 2010: 48.

Worker
Lucky and Ward (2010) – HL 2.15–2.41, HW 1.16–1.47, MFC 0.24–0.29, IOD 0.64–0.74, SL 3.70–4.38, EL 0.38–0.51, WL 3.98–4.28, PW 1.02–1.12, DPW 0.41–0.48, HTL 4.90–5.60, HTWmin 0.13–0.17, HTWmax 0.18–0.24, CI 0.53–0.61, SI 2.83–3.64, OI 0.10–0.12, HTC 0.64–0.81.

As in Leptomyrmex rufipes: medium sized species with head long and slender, excluding mandibles nearly twice as long as broad. Head widest at eye level, sides of head subparallel, narrowing anteriorly, genae slightly concave. Beyond eyes narrowing abruptly to dorsoventrally flattened and posteriorly projecting neck-like constriction at posterior margin. Masticatory margin of mandible with 15 to 20 teeth and denticles interspersed. Anterior clypeal margin flat to weakly concave. Eyes positioned approximately at midline of head, eyes small, convex, hairless, not reaching lateral margins. Antennae long and slender, not compressed, scapes surpassing posterior margin of head by 2/3 their length.

Pronotum slender, elongate. Propodeum short, dorsal face of propodeum with transverse impression at anterior end, declivitous face short and convex, propodeal angle very rounded. Petiole triangular in profile, posterior face with median longitudinal impression, dorsum rounded, posterior face longer than anterior face. Ventral surface of petiole nearly flat. Gaster elongate-elliptica''L. Legs very long and slender, not compressed.

Surface very finely shagreened and somewhat shining throughout. Mandibles with a coarse row of punctures along margin. Pubescence pale, sparse. Hairs minimal, confined to clypeus, venter and gaster. Body black with red head and antennae. Tarsi and tibiae yellow, gaster entirely black with anal orifice pale yellow.

Male
Lucky and Ward (2010) – HL 1.86–1.94, HW 1.30–1.35, SL 0.51–0.57, EL 0.68–0.70, HTL 4.68–4.89, CI 0.67–0.71, SI 0.39–0.42, SI2 0.85–0.89.

Wheeler (1934) - Head elongate-elliptical, including the mandibles twice as long as its transverse diameter through the eyes, the latter very large and protuberant, somewhat nearer the anterior clypeal than the occipital border, which is straight; the sides behind the eyes evenly rounded and gradually converging posteriorly; cheeks nearly straight, half as long as the eyes, converging anteriorly. Ocelli large and prominent. Mandibles small, with sharply truncated tips, their masticatory border short, without denticles, scarcely longer than the basal border. Clypeus nearly as long as broad, rather fiat, indistinctly subcarinate, with broadly rounded anterior border. Antennal scapes short, not more than three times as long as broad; first funicular joint as broad as long, second joint slightly shorter, third longer than the scape. Thorax resembling that of the other species but more slender, with less overhanging and narrower mesonotum and much less protuberant mesepisterna; epinotum very low, its base concave in profile, passing into the short and very sloping declivity without a distinct angle. Petiole nearly as broad as long, its node low and indistinct, in profile with longer anterior slope meeting the posterior slope at an obtuse angle. Gaster narrow, elongate-elliptical. Genitalia small but extruded; stipites triangular, longer than broad, with rather acute tips; volsellae rather stout, boot-shaped, the anterior prong very long, slender and aciculate, the posterior prong reduced to a point. Legs long and slender; middle tibiae and hind femora bowed. Wings short, measuring only 6 mm.; pterostigmal appendage long and ribbon-shaped; cubitus complete.

Moderately smooth and shining throughout, very delicately shagreened; mandibles opaque; squamulae of genitalia very smooth and shining.

Hairs almost absent, present on the venter where they are very short, and on the stipites where they are very fine, long and dense. Pubescence delicate and dilute, most distinct on the gaster.

Yellow throughout, except the squamulre which are reddish brown, even the wings tinged with yellow and with yellow veins.

References based on Global Ant Biodiversity Informatics

 * Lucky A., and P. S. Ward. 2010. Taxonomic revision of the ant genus Leptomyrmex Mayr (Hymenoptera: Formicidae). Zootaxa 2688: 1-67.
 * Van Ingen L. T., R. Campos, and A. N. Andersen. 2008. Ant community structure along an extended rain forest-savanna gradient in tropical Australia. Journal of Tropical Ecology 24: 445-455.
 * Wheeler W. M. 1934. A second revision of the ants of the genus Leptomyrmex Mayr. Bulletin of the Museum of Comparative Zoology 77: 69-118.