Leptomyrmex mjobergi

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

Leptomyrmex mjobergi side view

Leptomyrmex mjobergi 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.

L. mjobergi has been recorded in rainforest, open rainforest, wet sclerophyll and eucalyptus forest. Nests occur in the soil and under rocks.

Identification

This smallest macro-Leptomyrmex species can be readily identified by both size (HW 0.82–0.87 mm; WL 2.58–2.97 mm) and by the presence of a strongly inclined, scale-like petiole (all others are node-like). Workers of L. mjobergi are approximately half the size of the larger species in the genus (e.g. Leptomyrmex tibialis HW 1.68–1.96 mm), but remain larger than any of the micro-Leptomyrmex (HW < 0.80 mm). Leptomyrmex mjobergi occurs from Queensland’s northern Wet Tropics to the state’s southern border with New South Wales. Although it is unicolorous black, this nearly hairless species is unlikely to be confused with the other entirely black macro-Leptomyrmex in Australia, Leptomyrmex unicolor, which is distinctly pubescent, and quite large and stout (HW 1.37–1.51 mm; WL 3.27–3.73).

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

Nomenclature

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

  • mjobergi. Leptomyrmex mjobergi Forel, 1915b: 84 (w.) AUSTRALIA. Lucky & Ward, 2010: 39 (ergatoid q., m.).

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 1.40–1.53, HW 0.82–0.87, MFC 0.15–0.18, IOD 0.46–0.51, SL 2.44–2.80, EL 0.33–0.38, WL 2.58–2.97, PW 0.75–0.85, DPW 0.29–0.33, HTL 2.17–3.30, HTWmin 0.09–0.14, HTWmax 0.17–0.21, CI 0.57–0.61, SI 2.85–3.34, OI 0.11–0.13, HTC 0.48–0.79.

Relatively small species (HW 0.82–0.87; WL 2.58–2.97). Head, excluding mandibles, nearly twice as long as broad (CI 0.57–0.61), with nearly straight and parallel sides. Postocular margin of head broadly rounded. Masticatory margin of mandible with approximately 20 small, mostly uniform teeth. Anterior clypeal margin convex. Eyes positioned approximately at the midline of the head; large, somewhat flattened to head, hairless and not surpassing lateral margins. Antennae lightly compressed, scape surpassing posterior margin of head by 3/5 of its length.

Pronotum approximately 1.5 times as long as broad, thorax distinctly laterally compressed. Propodeum abruptly raised from mesonotum; dorsal surface twice as long as declivity, dorsal face weakly convex. Petiole flattened and scale-like, strongly inclined forward, twice as high as long, rounded at apex, ventral surface feebly convex. Gaster elongate-elliptical.

Body surface finely shagreened, somewhat shining, with delicate short sparse pubescence throughout. Standing hairs sparse, confined to gaster, venter, clypeus and mandibles. Body black, mandibles reddish-brown, femora scapes and tibiae brown, tarsi reddish-yellow.

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. Petiole node-like and vertical, not scale-like or inclined forward, taller than broad, rounded dorsally. Gaster globose, larger than in worker. Scapes, femora and tibiae broad, distinctly robust. Surface of body appearing velvety, shagreened.

Male

Lucky and Ward (2010) – measurements (n = 4) HL 1.14–1.26, HW 0.84–0.95, SL 0.17–0.18, EL 0.53–0.64, HTL 2.72–2.90, CI 0.73–0.78, SI 0.19–0.20, SI2 0.53–0.65.

References

  • Forel, A. 1915b. Results of Dr. E. Mjöbergs Swedish Scientific Expeditions to Australia 1910-13. 2. Ameisen. Ark. Zool. 9(1 16: 1-119 (page 84, worker described)
  • Lucky, A. 2011. Molecular phylogeny and biogeography of the spider ants, genus Leptomyrmex Mayr (Hymenoptera: Formicidae). Molecular Phylogenetics and Evolution 59: 281-292.
  • Lucky, A. & Ward, P.S. 2010. Taxonomic revision of the ant genus Leptomyrmex Mayr. Zootaxa 2688: 1-67.