Leptomyrmex rufithorax

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Leptomyrmex rufithorax
Leptomyrmex rufithorax
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dolichoderinae
Genus: Leptomyrmex
Species: L. rufithorax
Binomial name
Leptomyrmex rufithorax
Forel, 1915

Leptomyrmex rufithorax side view

Leptomyrmex rufithorax top view

Specimen labels

Synonyms
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.

L. rufithorax has been recorded in rainforest, wet sclerophyll and dry sclerophyll. Nests occur in soil, in and under logs, and under rocks.

Identification

Workers of L. rufithorax are large with a broad head that is round to flat at the postocular margin, and lacking a necklike constriction. The coloration of this species is distinctive: the head, mesosoma and first gastral tergite (3rd abdominal segment) are red, the distal 2/3 of the gaster and the legs, including the coxae, are black. This species occurs in central- and south-east Queensland, where its dark coxae in combination with pale mesosoma distinguish it from sympatric congeners. L. rufithorax may resemble some dark forms of Leptomyrmex erythrocephalus (in northern New South Wales), but in these forms the gaster is uniformly black and the femora are often pale basally. In L. rufithorax workers the femora and tibiae are entirely black, with joints and tarsi showing the only hint of orange. (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

Nomenclature

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

  • rufithorax. Leptomyrmex erythrocephalus var. rufithorax Forel, 1915b: 83 (w.) AUSTRALIA. Wheeler, W.M. 1934c: 91 (m.); Lucky & Ward, 2010: 54 (ergatoid q.). Subspecies of erythrocephalus: Wheeler, W.M. 1934c: 91. Raised to species: Lucky & Ward, 2010: 53. Senior synonym of basirufus: Lucky & Ward, 2010: 53.
  • basirufus. Leptomyrmex erythrocephalus subsp. basirufus Wheeler, W.M. 1934c: 90 (w.) AUSTRALIA. Junior synonym of rufithorax: Lucky & Ward, 2010: 53.

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) - measurements (n = 10) HL 2.17–2.36, HW 1.34–1.56, MFC 0.28–0.37, IOD 0.81–0.92, SL 3.73–4.07, EL 0.38–0.46, WL 4.04–4.35, PW 1.12–1.34, DPW 0.41–0.51, HTL 4.67–5.13, HTWmin 0.14–0.21, HTWmax 0.26–0.30, CI 0.61–0.66, SI 2.60–2.86, OI 0.09–0.11, HTC 0.47–0.77.

Larger species (HL 2.17–2.36, HW 1.34–1.56) with broad head (CI 0.61–0.66). Head widest at eyes, sides of head convex around eyes, genae concave, posterior to eyes rounding to slightly narrowed flat postocular margin. Posterior portion of head lacking neck-like constriction. Masticatory margin of mandible with approximately 15 teeth and denticles interspersed. Anterior clypeal margin medially concave. Eyes positioned toward posterior part of head. Eyes small, round, hairless, not surpassing lateral margins of head. Antennal scapes not compressed, extending beyond the posterior margin less than 2/3 of their length.

Pronotum short. Declivity of propodeum about half the length of the dorsal face, dorsal face with transverse impression at anterior end, propodeal angle very rounded. Petiolar node triangular in profile, summit convex and rounded, with slight longitudinal impression on dorsum, anterior and posterior faces, anterior face slightly shorter than posterior face, ventral surface of petiole concave. Gaster elliptical-elongate. Legs somewhat compressed.

Body surface slightly shining, finely shagreened. Mandibles with a row of coarse punctures along margin. Pubescence fine. Greyish pilosity minimal, confined to clypeus, venter and gaster. Body and head rufotestaceous, with legs and gaster black. Head and antennae deep reddish orange, femora and tibiae dark brown, joints and tarsi yellow. Gaster black, but first segment rufotestaceous with dark outer margin.

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. Dorsal face of propodeum high, convex. Petiole broader than high, with distinct medial impression. Gaster globose, larger than in worker. Scapes, femora and tibiae broad, robust. Surface of body appearing dusty, not shining. Queen coloration as in workers.

Male

Lucky and Ward (2010) - (n = 3) HL 1.70–1.80, HW 1.26–1.33, SL 0.38–0.44, EL 0.62–0.63, HTL 4.26–4.50, CI 0.73–0.76, SI 0.29–0.33, SI2 0.66–0.76.

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