Leptomyrmex wiburdi

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

Leptomyrmex wiburdi side view

Leptomyrmex wiburdi 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. wiburdi has been recorded in rainforest, wet sclerophyll and dry sclerophyll. Nests occur in soil, in standing or fallen trees or snags, in stumps, and under rocks.

Identification

This species can be distinguished by its broad head, which is widest posterior of the eyes, short scapes and generally small size. L. wiburdi can be easily mistaken for Leptomyrmex cnemidatus or Leptomyrmex erythrocephalus, as the general body shape and round postocular portion of the head are similar amongst these three species which co-occur in New South Wales. There is no ‘typical’ color pattern that characterizes L. wiburdi workers, rather they take on a variety of color patterns, including the typical patterns seen in L. cnemidatus and L. erythrocephalus; workers with different color forms have even been observed in a single nest. Many individuals possess mottled brown-black coloration on the head and mesosoma, which is not seen in either L. cnemidatus or L. erythrocephalus. L. wiburdi workers evidently mimic workers of co-occurring species of Leptomyrmex. (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

Worker

Colour variation in L. wiburdi.

Nomenclature

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

  • pictus. Leptomyrmex wiburdi var. pictus Wheeler, W.M. 1915d: 273 (w.) AUSTRALIA. Wheeler, G.C. & Wheeler, J. 1966: 728 (l.). Subspecies of wiburdi: Wheeler, W.M. 1934c: 101. Junior synonym of wiburdi: Lucky & Ward, 2010: 60.
  • wiburdi. Leptomyrmex wiburdi Wheeler, W.M. 1915d: 272, fig. 7 (w.) AUSTRALIA. Wheeler, W.M. 1934c: 99 (m.); ; Lucky & Ward, 2010: 61 (ergatoid q.). Senior synonym of pictus: Lucky & Ward, 2010: 60.

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 = 12)HL 1.65–1.94, HW 1.15–1.33, MFC 0.27–0.36, IOD 0.70–0.86, SL 2.74–3.3, EL 0.36–0.45, WL 3.06–3.65, PW 0.94–1.15, DPW 0.30–0.43, HTL 3.32–3.88, HTWmin 0.13–0.17, HTWmax 0.22–0.26, CI 0.66–0.70, SI 2.29–2.64, OI 0.09–0.12, HTC 0.56–0.69.

Relatively small species (HL 1.65–1.94; HW 1.15–1.33) with broad head (CI 0.66–0.70), excluding mandibles head width more than 3/5 of length. Head widest posterior to eyes, sides of head straight, narrowing anteriorly, genae slightly concave. Beyond eyes head broadly and distinctly rounding into posterior margin. Masticatory margin of mandible with approximately 20 teeth and denticles interspersed. Anterior clypeal margin medially concave. Eyes positioned posteriorly to midline of head, relatively large, hairless, not surpassing margins of head. Antennal scapes relatively short, not compressed, surpassing posterior margin of the head by less than 2/3 their length.

Pronotum stout, very convex. Dorsal face of propodeum more than twice as long as declivity, angle joining the two very broadly rounded. Propodeum with distinct transverse impression at anterior end. Petiole triangular in profile, dorsum with medial longitudinal impression, anterior face not much longer than posterior face, ventral suface of petiole distinctly projecting. Gaster ellipticaL. Legs relatively short, tibiae distinctly compressed.

Surface subopaque, very finely and densely shagreened. Mandibles slightly shining, coarsely punctate along apical border. Pubescence extremely fine, giving the body a pruinose appearance. Hairs few, confined to clypeus, mandibles and venter.

Coloration extremely variable; ranging from erythrocephalus-like to rufipes-like coloration, with many intermediate states apparently co-occurring. A common color pattern presents a rufotestaceous head obfuscated toward the postocular margin, mottled dark brown to black mesosoma and legs with joints and sutures pale, black gaster, and mandibles, antennae and tarsi rufotestaceous.

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. The anterior portion of the mesonotum with a slight medial bump. Dorsal face of propodeum raised, convex. Petiole broader than high. Gaster globose, larger than in worker. Scapes, femora and tibiae broad, robust. Surface of body appearing dusty, shagreened.

Male

Lucky and Ward (2010) – measurements (n = 4) HL 1.39–1.48, HW 1.09–1.15, SL 0.48–0.54, EL 0.54–0.61, HTL 3.14–3.42, CI 0.76–0.81, SI 0.42–0.49, SI2 1.10–1.33.

Wheeler (1934) - Head, including the mandibles, twice as long as broad, the postocular portion subtrapezoidal, with straight posterior and lateral borders and rounded posterior corners. Eyes very convex, subreniform, with sinuate internal orbits, only about twice as long as the concave, subparallel cheeks and therefore intermediate in size between the eyes of L. erythrocephalus cnemidatus and L. nigriventris. Ocelli also intermediate. Mandibles short and thick, with obtuse tips, their masticatory border short and not distinctly denticulate, scarcely longer than the basal border with which it forms a rounded obtuse angle. Antennal scapes nearly four times as long as broad; first funicular joint slightly longer than broad, second joint twice as long; joints 3-6 much longer, bent near their base. Thorax shaped as in the species previously described, but the base of the epinotum in profile straight and only twice as long as the straight sloping declivity and forming a distinct obtuse angle with it. Petiole very slightly longer than broad; its node much lower and less differentiated than in the worker; in profile somewhat higher and feebly angular in the middle; ventral surface only slightly convex anteriorly. Gaster clavate, narrow at the base, enlarged at the tip. Genitalia large, extruded; stipites oval, or rounded-triangular, longer than broad, punctate, densely and finely pilose; volsellae rather broad, boot-shaped. Legs short; tibiae terete, median pair bowed, hind pair feebly flexuous. Wings rather small (7 mm.) pterostigmal appendage pedunculate, sausage-shaped; basal two-fifths of cubitus absent.

Subopaque; gaster more shining, rather finely and sharply shagreened.

Hairs almost absent, except on the stipites and cerci; very few on the mandibles. Pubescence yellowish, very fine, appressed, most distinct on the gaster, head, epinotum and mesopleurae.

Pale brownish yellow; gaster dark brown, except the base of its first segment, which is yellow, and the genital squamulae, which are rich castaneous brown, very smooth and shining. Pleurae, epinotum and dorsal surface of petiole clouded with fuscous. Wings yellow, with pale 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. 1915e. The Australian honey-ants of the genus Leptomyrmex Mayr. Proc. Am. Acad. Arts Sci. 51: 255-286 (page 272, fig. 7 worker described)
  • Wheeler, W. M. 1934c. A second revision of the ants of the genus Leptomyrmex Mayr. Bull. Mus. Comp. Zool. 77: 69-118 (page 99, male described)