Aenictus pachycerus

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Aenictus pachycerus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dorylinae
Genus: Aenictus
Species: A. pachycerus
Binomial name
Aenictus pachycerus
(Smith, F., 1858)

Aenictus pachycerus casent0217379 p 1 high.jpg

Aenictus pachycerus casent0217379 d 1 high.jpg

Specimen Labels

Synonyms

Nothing is known about the biology of Aenictus pachycerus.

Identification

A member of the pachycerus group.

Key to Aenictus species groups

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Oriental Region: India (type locality), Sri Lanka.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Little is known about the biology of Aenictus pachycerus. The genus is comprised of species that live an army ant lifestyle. Aenictus typically prey on other ants, from other genera, or other insects such as wasps or termites. There are reports of Aenictus preying on other insects as well and even have been observed collecting honeydew from homopterans (Santschi, 1933; Gotwald, 1995) but this appears, at least from available evidence, to be uncommon. Foraging raids can occur day or night across the ground surface. Occasionally raids are arboreal. During a raid numerous workers attack a single nest or small area, with several workers coordinating their efforts to carry large prey items back to the nest or bivouac. Aenictus have a nomadic life style, alternating between a migratory phase in which nests are temporary bivouacs in sheltered places above the ground and a stationary phase where semi-permanent underground nests are formed. During the nomadic phase bivouacs move regularly, sometimes more than once a day when larvae require large amounts of food. Individual nests usually contain up to several thousand workers, although nest fragments containing only a few hundred workers are often encountered. Queens are highly specialised and look less like workers than in most ant species. They have greatly enlarged gasters (dichthadiform) and remain flightless throughout their life. New colonies are formed by the division of existing colonies (fission) rather than by individual queens starting colonies on their own.

Castes

Known only from the worker caste.

Wilson 1964 Army Ant fig 64-75

Nomenclature

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

  • pachycerus. Eciton pachycerus Smith, F. 1858b: 153 (w.) "South America ?" (in error; type-locality INDIA, see Bingham, 1903: 21). Bharti, 2003a: 715 (q.). Combination in Aenictus: Dalla Torre, 1893: 8. Senior synonym of bengalensis: Bingham, 1903: 20; of continuus: Wilson, 1964a: 471.
  • bengalensis. Typhlatta bengalensis Mayr, 1879: 669 (w.) INDIA. Combination in Aenictus: Dalla Torre, 1893: 7. Junior synonym of pachycerus: Bingham, 1903: 20.
  • continuus. Aenictus bengalensis var. continuus Forel, 1901a: 476 (w.) SRI LANKA. Junior synonym of pachycerus: Wilson, 1964a: 471.

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

Description

Worker

Wilson (1964) - Syntypes: HW 0.71 mm, HL 0.82mm, SL 0.63mm; HW 0.71 mm, HL 0.83mm, SL 0.65 mm. Antenna 10-segmented. Mandible typical. Clypeus strongly convex, entire, unarmed. Parafrontal ridge very distinct, 0.3 mm in length, in side view forming a prosalient lobe. Occiput weakly convex, lacking collar. Propodeal junction acutely angulate. Subpetiolar process a large, evenly rounded lobe which projects slightly forward. Pilosity moderately abundant and relatively long; length of longest pronotal hairs 0.28 mm.

Head everywhere weakly microreticulate, the reticular diameters about 0.01 mm; vertex, area immediately surrounding parafrontal ridges, and clypeus subopaque; remainder of head feebly shining; mesosoma and pedicel entirely microreticulate, with reticular diameter about 0.01 mm; body everywhere opaque, except over most of pronotal dorsum, which is feebly shining. Concolorous medium reddish brown.

References

  • Bharti, H. 2003b. Queen of the army ant Aenictus pachycereus (Hymenoptera, Formicidae, Aenictinae). Sociobiology 42: 715-718 PDF
  • Bingham, C. T. 1903. The fauna of British India, including Ceylon and Burma. Hymenoptera, Vol. II. Ants and Cuckoo-wasps. London: Taylor and Francis, 506 pp. (page 21, type locality India)
  • Bingham, C. T. 1903. The fauna of British India, including Ceylon and Burma. Hymenoptera, Vol. II. Ants and Cuckoo-wasps. London: Taylor and Francis, 506 pp. (page 20, senior synonym of bengalensis)
  • Bolton, B. 1995b. A new general catalogue of the ants of the world. Cambridge, Mass.: Harvard University Press, 504 pp. (page 60, catalogue)
  • Dalla Torre, K. W. von. 1893. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus. Vol. 7. Formicidae (Heterogyna). Leipzig: W. Engelmann, 289 pp. (page 8, Combination in Aenictus)
  • Smith, F. 1858a. Catalogue of hymenopterous insects in the collection of the British Museum. Part VI. Formicidae. London: British Museum, 216 pp. (page 153, worker described)
  • Wilson, E. O. 1964a. The true army ants of the Indo-Australian area (Hymenoptera: Formicidae: Dorylinae). Pac. Insects 6: 427-483 (page 471, senior synonym of continuus)