Leptomyrmex ruficeps

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Leptomyrmex ruficeps
Leptomyrmex ruficeps
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dolichoderinae
Genus: Leptomyrmex
Species: L. ruficeps
Binomial name
Leptomyrmex ruficeps
Emery, 1895

Leptomyrmex ruficeps side view

Leptomyrmex ruficeps top view

Specimen labels

Evolutionary Relationships
Leptomyrmex
Neotropical

Leptomyrmex neotropicus (fossil only)



Leptomyrmex relictus



Australasian
Micro-Leptomyrmex

Leptomyrmex burwelli



Leptomyrmex dolichoscapus



Macro-Leptomyrmex


Leptomyrmex mjobergi




Leptomyrmex varians




Leptomyrmex unicolor





Leptomyrmex flavitarsus



Leptomyrmex puberulus





Leptomyrmex darlingtoni




Leptomyrmex fragilis



Leptomyrmex niger











Leptomyrmex erythrocephalus




Leptomyrmex wiburdi




Leptomyrmex cnemidatus




Leptomyrmex nigriventris



Leptomyrmex tibialis









Leptomyrmex geniculatus




Leptomyrmex nigriceps



Leptomyrmex pallens






Leptomyrmex rufithorax




Leptomyrmex rufipes




Leptomyrmex rothneyi



Leptomyrmex ruficeps










Based on Barden et al., 2017. Note only selected Leptomyrmex species are included.

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

Distribution

Distribution based on Regional Taxon Lists

Australasian Region: Australia (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

These conspicuous ants are most often encountered individually or as small groups of 2 or 3 foragers on the surface of the ground any time of the day or night. Because of their long legs and thin bodies, they superficially resemble spiders. This is especially true when they are disturbed, as they extend their legs, raise their gasters, and run quickly to escape danger. This has led to their being given the common name "spider ants."

Nests are found in soil or in dead wood, either standing or on the ground, and are often at the base of trees. Colony sizes average a few hundred workers and a single queen. In all but a handful of species, the queen is wingless and worker-like, differing from workers only in being slightly larger and with an enlarged mesosoma. In a few species the queens are fully winged, as they are in most other ants.

When a large source of food is found, workers of Leptomyrmex will return to their nest and recruit additional workers to help utilise the newly found resource. They also use workers as "living storage vessels". These special workers, called repletes, accept liquids from returning foragers who transfer their liquid foods to these selected workers. These special workers continue to accept liquids until their gasters become greatly enlarged and extended. When enlarged, repletes cannot escape the nest and remain inside suspended from the ceiling. They can retain these fluids for extended periods and dispense it on demand when food is in short supply.

Castes

Queens have yet to be collected.

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • 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.

Type Material

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

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-ellipticaL. 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

  • Lucky, A. 2011. Molecular phylogeny and biogeography of the spider ants, genus Leptomyrmex Mayr (Hymenoptera: Formicidae). Molecular Phylogenetics and Evolution 59: 281-292. doi:10.1016/j.ympev.2011.03.004
  • Lucky, A. & Ward, P.S. 2010. Taxonomic revision of the ant genus Leptomyrmex Mayr. Zootaxa 2688: 1-67. PDF
  • Wheeler, W. M. 1934c. A second revision of the ants of the genus Leptomyrmex Mayr. Bull. Mus. Comp. Zool. 77: 69-118.