Leptomyrmex melanoticus

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Leptomyrmex melanoticus
Leptomyrmex melanoticus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dolichoderinae
Genus: Leptomyrmex
Species: L. melanoticus
Binomial name
Leptomyrmex melanoticus
Wheeler, W.M., 1934

Leptomyrmex melanoticus side view

Leptomyrmex melanoticus top view

Specimen labels

Synonyms

Collected in rainforest. Nesting habits are unknown.

Identification

Lucky and Ward (2010) – L. melanoticus is distinctively slender, unicolorous black and virtually hairless. It is unlikely to be confused with the stout and hairy Leptomyrmex flavitarsus, but superficially does resemble Leptomyrmex niger. L. melanoticus can be distinguished from this species by its narrow and conical ‘neck’, an extension of the posterior portion of the head not found in L. niger. The round eyes of L. melanoticus (EL 0.36–0.39) are generally smaller than the large, elongate eyes of L. niger (EL 0.38–0.47 mm). Additionally, the propodeal angle of this species gradu¬ally rounds into the dorsal and posterior faces, in contrast to the distinct angle of the propodeum of L. niger. See the discussion of L. fragilis for consideration of the close relationship between L. melanoticus and L. fragilis. (Lucky and Ward 2010)

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: New Guinea (type locality).

Distribution based on specimens

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The above specimen data are provided by AntWeb. Please see Leptomyrmex melanoticus for further details

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.

  • melanoticus. Leptomyrmex fragilis subsp. melanoticus Wheeler, W.M. 1934c: 113, fig. 15 (w.m.) NEW GUINEA. Raised to species: Lucky & Ward, 2010: 38. Senior synonym of contractus: Lucky & Ward, 2010: 38.
  • contractus. Leptomyrmex contractus Donisthorpe, 1947c: 586 (w.) NEW GUINEA. Junior synonym of melanoticus: Lucky & Ward, 2010: 38.

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 = 6) HL 1.77–2.00, HW 0.99–1.06, MFC 0.18–0.24, IOD 0.56–0.61, SL 3.96–4.54, EL 0.36–0.39, WL 3.32–3.76, PW 0.86–1.01, DPW 0.27–0.35, HTL 4.34–5.09, HTWmin 0.10–0.13, HTWmax 0.15–0.19, CI 0.54–0.56, SI 4.02–4.05, OI 0.11–0.15, HTC 0.62–0.75.

As in Leptomyrmex fragilis, but body unicolorous black with only the antennal funiculi, the mandibles and the tarsi pale yellow.

Male

Lucky and Ward (2010) – measurements (n = 2) HL 1.46–1.52, HW 1.04–1.05, SL 0.37–0.38, EL 0.64, HTL 4.78–4.83, CI 0.68–0.72, SI 0.36–0.37, SI2 1.08–1.09.

Wheeler (1934) - Head without the mandibles nearly twice as long as its width through the eyes, which are unusually large and convex, with feebly sinuate internal orbits and situated distinctly in front of the middle of the head. Cheeks more than half as long as the eyes, concave, converging anteriorly. Postocular borders of head long, very feebly concave, rapidly converging to the short, straight occipital border. Ocelli large but not prominent. Mandibles small and narrow, with pointed tips, their masticatory border without denticles, somewhat longer than the basal border and curving into it without a perceptible angle. Clypeus as long as broad. Antennae very long and slender, fully as long as the body; scapes two and one-half times as long as broad; first funicular joint half as long as the scapes, joint 2 of the same length as the first, succeeding joints much longer, feebly flexuous. Thorax long, mesonotum one and one-half times as long as broad, narrowed anteriorly where it is very convex and strongly overarching the pronotum; mesepisterna very protuberant as in the other species; epinotum low, its base straight in profile, nearly three times as long as the straight, sloping declivity, with which it forms a distinct angle, marked on each side by the projecting epinotal stigma. Petiole from above twice as long as broad, broader behind than in front, with straight sides; in profile without a distinct node, its dorsal and ventral surfaces nearly parallel, the dorsal slightly convex, the ventral straight. Genitalia retracted basally, their appendages exserted and spread; stipites small, subtriangular, longer than broad, with bluntly rounded tip, their ventral border with numerous long cilia; volsella long, flattened, hook-shaped, membraneous at the base where it bears a slender, styliform lacinia; sagittae flattened, subtriangular, with straight dorsal border, rounded tip and convex, serrate ventral border. Legs extremely long and slender, middle tibiae bowed, fore and hind tibiae flexuous, the latter very strongly so. Wings short, measuring only 5 mm.; apterostigmal appendage minute, nodiform; basal half of cubital vein absent.

Lustrous or somewhat shining, very finely shagreened or punctulate.

Hairs and pubescence pale, the former short, absent, except on the stipites, lower surface of petiole and anterior border of clypeus; pubescence rather long, appressed, not very dense, generally distributed. Head, thorax, gaster, dorsal surface of petiole and coxae dark brown; mandibles, clypeus, scapes, front, sutures of thorax, wing-insertions, ventral portion of petiole and genital appendages yellowish brown or brownish yellow; femora paler brown than the coxae, their tips, the tibial, tarsi and funiculi white. Wings distinctly infuscated, with brown veins.

Type Material

Wheeler (1934) - Described from six workers and two males taken by Mr. W. J. Eyerdam at China Straight, New Guinea (Papua).

Lucky and Ward (2010) - Syntypes, 6 workers, 2 males, Papua New Guinea: China Straight (Eyerdam, W.J.) Museum of Comparative Zoology. L. contractus Syntype, 1 worker, Papua New Guinea: KB Mission (Krombein, K.V.) The Natural History Museum.

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.