Leptomyrmex mjobergi

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

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

At a Glance

• Replete Workers

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

• Key to Australian Leptomyrmex Species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: -16.46666667° to -27.56°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: AntMaps

Distribution based on Regional Taxon Lists

Australasian Region: Australia (type locality).

Distribution based on AntMaps

Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.

Elevation Range

Occurrence at collecting sites during elevational surveys of rainforest in the Eungella region, Queensland, Australia (Burwell et al., 2020).

Species	Elevation (m asl)
	200	400	600	800	1000	1200
Leptomyrmex mjobergi	20-30	60-70	40-50
Shading indicates the bands of elevation where species was recorded. Numbers are the percentage of total samples containing this species.

Biology

Explore Overview of Leptomyrmex 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

Images from AntWeb

Worker. Specimen code casent0127040. Photographer Andrea Lucky, uploaded by California Academy of Sciences.	Owned by PSWC, Philip S. Ward Collection.

Phylogeny

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.

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

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

Type Material

• Syntype, 2 workers, Colosseum, Queensland, Australia, Musee d'Histoire Naturelle Genève.
• Syntype, 2 workers, Tolga, Queensland, Australia, Musee d'Histoire Naturelle Genève.
• Syntype, unspecified, Herberton, Queensland, Australia.

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

• Burwell, C.J., Nakamura, A. 2020. Rainforest ants (Hymenoptera: Formicidae) along an elevational gradient at Eungella in the Clarke Range, Central Queensland coast, Australia. Proceedings of the Royal Society of Queensland 125: 43-63.
• 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. & Ward, P.S. 2010. Taxonomic revision of the ant genus Leptomyrmex Mayr. Zootaxa 2688: 1-67.
• Lucky, A. 2011. Molecular phylogeny and biogeography of the spider ants, genus Leptomyrmex Mayr (Hymenoptera: Formicidae). Molecular Phylogenetics and Evolution 59: 281-292.
• Oberski, J.T. 2024. Ultraconserved element (UCE) phylogenomics illuminates the evolutionary history and biogeography of Dorymyrmex pyramid ants. Systematic Entomology, 1-24 (doi:10.1111/syen.12658).

References based on Global Ant Biodiversity Informatics

• Lucky A., and P. S. Ward. 2010. Taxonomic revision of the ant genus Leptomyrmex Mayr (Hymenoptera: Formicidae). Zootaxa 2688: 1-67.
• Wheeler W. M. 1915. The Australian honey-ants of the genus Leptomyrmex Mayr. Proceedings of the American Academy of Arts and Sciences 51: 255-286.