Onychomyrmex mjobergi

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Onychomyrmex mjobergi
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Amblyoponinae
Tribe: Amblyoponini
Genus: Onychomyrmex
Species: O. mjobergi
Binomial name
Onychomyrmex mjobergi
Forel, 1915

Onychomyrmex mjobergi casent0104585 profile 1.jpg

Onychomyrmex mjobergi casent0104585 dorsal 1.jpg

Specimen labels

October 24, I found two fine colonies of this species in rotten logs. One comprised at least 400 workers, a single queen, with the abdomen greatly distended with eggs, and a large number of nearly mature larvae but no pupae. The other colony was somewhat less populous but also contained many larvae. The ants moved rather slowly in long files through the cracks in the wood, evidently endeavoring to keep in close touch with one another by means of their antennae, after the manner of the Dorylinae. They stung severely for such small insects. (Wheeler 1916)

Identification

Wheeler (1916) - The worker of O. mjobergi is readily distinguished from that of Onychomyrmex hedleyi by its paler color, shorter head, antennal scapes and funicular joints, the straight dorsal profile of the thorax, broader epinotum and petiole, deeper constriction between the postpetiole and gaster, and smooth, shining, and sparsely punctate mandibles.

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: -16.3° to -21.16864°.

 
North
Temperate
North
Subtropical
Tropical South
Subtropical
South
Temperate

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

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.
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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.
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Biology

Castes

Worker

Images from AntWeb

Onychomyrmex mjobergi casent0172295 head 1.jpgOnychomyrmex mjobergi casent0172295 profile 1.jpgOnychomyrmex mjobergi casent0172295 dorsal 1.jpgOnychomyrmex mjobergi casent0172295 label 1.jpg
Worker. Specimen code casent0172295. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by ANIC, Canberra, Australia.
Onychomyrmex mjobergi casent0172296 head 1.jpgOnychomyrmex mjobergi casent0172296 profile 1.jpgOnychomyrmex mjobergi casent0172296 dorsal 1.jpgOnychomyrmex mjobergi casent0172296 label 1.jpg
Worker. Specimen code casent0172296. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by ANIC, Canberra, Australia.

Nomenclature

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

  • mjobergi. Onychomyrmex mjobergi Forel, 1915b: 2, textfig. 1; pl. 1, fig. 7 (w.) AUSTRALIA (Queensland).
    • Type-material: syntype workers (number not stated).
    • Type-localities: Australia: Queensland, Herberton, Atherton, and Cedar Creek (E. Mjöberg).
    • Type-depository: MHNG, NHMB.
    • Wheeler, W.M. 1916a: 52 (q.l.); Wheeler, G.C. & Wheeler, J. 1952c: 638 (l.).
    • Status as species: Wheeler, W.M. 1916a: 51 (redescription); Brown, 1960a: 181, 223; Taylor & Brown, 1985: 37; Taylor, 1987a: 50; Bolton, 1995b: 300.
    • Distribution: Australia.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Wheeler (1916) - Length 3.5-4 mm.

Head subrectangular, not more than i longer than broad, scarcely broader in front than behind, with feebly and evenly convex sides, feebly concave posterior border and rounded posterior corners. Clypeus with broadly arcuate anterior border, sinuate on each side, minutely and evenly denticulate. Eyes scarcely smaller than in Onychomyrmex hedleyi, situated about 2/3 the distance from the anterior to the posterior border of the head. Mandibles similar to those of hedleyi. Antennae shorter, scapes only 2/3 as long as the head, first and last funicular joints nearly twice as long as broad, remaining joints not longer than broad, the more basal joints a little broader than long. Thorax differing from that of hedleyi in being stouter and in having the dorsal outline nearly straight in profile, the pronotum being convex only at the extreme anterior end and the mesonotum less impressed. Thoracic sutures very distinct but less impressed than in hedleyi. Mesonotum fully three times as broad as long. Petiole with very short peduncle, anterior surface of node more concave, its upper surface seen from above distinctly broader than long, with very convex sides. Constriction between the postpetiole and gaster somewhat deeper than in hedleyi, legs stouter.

Smooth and shining; mandibles shining, not striate but sparsely punctate, like the remainder of the body. Punctures on the head coarser than in hedleyi, and more abundant, especially on the cheeks and sides of the front. Clypeus subopaque, rugulose-punctate.

Hairs similar to those of hedleyi but coarser and of rather uneven length, pale yellow.

Rich ferruginous red, clypeus darker; tarsal claws, sutures of thorax and gaster, articulations of antennal funiculi dark brown, mandibular teeth black; legs and anal segments of gaster paler and more yellowish.

Queen

Wheeler (1916) - Length nearly 5.5 mm.

Head a little longer than broad and nearly as broad in front as long, with prominent, depressed anterior corners, the sides converging posteriorly, with two transverse impressions, one half-way between the anterior corner and the eye and one at the eye. Eyes as small as in the worker, but more elongate. Mandibles with less abruptly incurved tips than in the worker and with only two indistinct teeth. Thorax more robust than in the worker, the pro- and epinotum with more convex sides and the pronotum more convex above, so that the mesonotum is more impressed in profile. From above the mesonotum is scarcely twice as broad as long. Petiole much larger than in the worker, with very short, slender peduncle, without ventral projection; node large, very convex in front, from above more than twice as broad as long, broader than the epinotum and nearly half as broad as the postpetiole. Gaster very much larger than in the worker, more than twice as long as broad. sub oblong, flattened dorsoventrally. Sculpture as in the worker, but the piligerous punctures, especially on the head, much coarser, almost foveolate and somewhat elongated on the sides of the front. Cheeks and sides of epinotum subopaque, finely rugulose-punctate.

Hairs coarser and longer, especially on the body, than in the worker.

Color more brownish ferruginous; mandibles, antennae, and legs more yellowish; pleurae, sides of petiole, and sutures of gaster brownish yellow.

Type Material

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 2, fig. 1; pl. 1, fig. 3 worker described)
  • Wheeler, G. C.; Wheeler, J. 1952c. The ant larvae of the subfamily Ponerinae - Part II. Am. Midl. Nat. 48: 604-672 (page 638, larva described)
  • Wheeler, W. M. 1916a. The Australian ants of the genus Onychomyrmex. Bulletin of the Museum of Comparative Zoology 60: 45-54 (page 52, queen, larva described)

References based on Global Ant Biodiversity Informatics

  • Brown W. L., Jr. 1960. Contributions toward a reclassification of the Formicidae. III. Tribe Amblyoponini (Hymenoptera). Bulletin of the Museum of Comparative Zoology 122: 143-230.