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


Nothing is known about the biology of Aenictus pachycerus.


A member of the pachycerus group.

Key to Aenictus species groups

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: 32.628611° to 8.333333333°.

Tropical South

Distribution based on Regional Taxon Lists

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

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.



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.


Known only from the worker caste.

Wilson 1964 Army Ant fig 64-75


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

  • pachycerus. Eciton pachycerus Smith, F. 1858b: 153 (w.) "Hab. South America?"
    • Type-material: syntype workers (number not stated).
    • Type-locality: “South America?” (Hardwick).
    • [Note: type-locality India, after Bingham, 1903: 21.]
    • Type-depository: BMNH.
    • Bharti, 2003a: 715 (q.).
    • Combination in Aenictus: Dalla Torre, 1893: 8.
    • Status as species: Mayr, 1863: 409; Roger, 1863b: 36; Dalla Torre, 1893: 8; Forel, 1895b: 121; Rothney, 1903: 96; Bingham, 1903: 20; Forel, 1906b: 90; Emery, 1910b: 30; Menozzi, 1939a: 327; Chapman & Capco, 1951: 11; Wilson, 1964a: 471; Bolton, 1995b: 60; Tiwari, 1999: 17; Bharti, 2003a: 714; Bharti, Wachkoo & Kumar, 2012: 294 (in key); Bharti, Guénard, et al. 2016: 21.
    • Senior synonym of bengalensis: Bingham, 1903: 20; Emery, 1910b: 30; Wilson, 1964a: 471; Bolton, 1995b: 60; Tiwari, 1999: 17.
    • Senior synonym of continuus: Wilson, 1964a: 471; Bolton, 1995b: 60.
    • Distribution: India, Sri Lanka.
  • bengalensis. Typhlatta bengalensis Mayr, 1879: 669 (w.) INDIA (West Bengal).
    • Type-material: holotype(?) worker.
    • [Note: no indication of number of specimens is given.]
    • Type-locality: India: Calcutta (Rothney).
    • Type-depository: NHMW.
    • Combination in Aenictus: Dalla Torre, 1893: 7.
    • Status as species: Dalla Torre, 1893: 7; Forel, 1901a: 476; Chapman & Capco, 1951: 10.
    • Junior synonym of pachycerus: Bingham, 1903: 20; Emery, 1910b: 30; Wilson, 1964a: 471; Bolton, 1995b: 59; Tiwari, 1999: 17.
  • continuus. Aenictus bengalensis var. continuus Forel, 1901a: 476 (w.) SRI LANKA, INDIA.
    • Type-material: syntype workers (number not stated).
    • Type-localities: Sri Lanka (“Ceylon”) (no further data), and India: Calcutta (Rothney).
    • Type-depository: MHNG.
    • Subspecies of bengalensis: Chapman & Capco, 1951: 10.
    • Subspecies of pachycerus: Emery, 1910b: 30.
    • Junior synonym of pachycerus: Wilson, 1964a: 471; Bolton, 1995b: 59.

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



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 based on Global Ant Biodiversity Informatics

  • Bharti H. 2003. Queen of the army ant Aenictus pachycereus (Hymenoptera, Formicidae, Aenictinae). Sociobiology 42: 715-718.
  • Bharti H., A. A. Wachkoo, and R. Kumar. 2017. First inventory of ants (Hymenoptera: Formicidae) in Northwestern Shivalik, India. Halteres 8: 33-68.
  • Bharti H., Y. P. Sharma, M. Bharti, and M. Pfeiffer. 2013. Ant species richness, endemicity and functional groups, along an elevational gradient in the Himalayas. Asian Myrmecology 5: 79-101.
  • Bharti H., Y. P. Sharma, and A. Kaur. 2009. Seasonal patterns of ants (Hymenoptera: Formicidae) in Punjab Shivalik. Halteres 1(1): 36-47.
  • Chapman, J. W., and Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327
  • Chapman, J.W. and S.R. Capco. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monographs of the Institute of Science and Technology (Manila) 1: 1- 327
  • Dias R. K. S. 2002. Current knowledge on ants of Sri Lanka. ANeT Newsletter 4: 17- 21.
  • Dias R. K. S. 2006. Current taxonomic status of ants (Hymenoptera: Formicidae) in Sri Lanka. The Fauna of Sri Lanka: 43-52. Bambaradeniya, C.N.B. (Editor), 2006. Fauna of Sri Lanka: Status of Taxonomy, Research and Conservation. The World Conservation Union, Colombo, Sri Lanka & Government of Sri Lanka. viii + 308pp.
  • Dias R. K. S. 2013. Diversity and importance of soil-dweeling ants. Proceedings of the National Symposium on Soil Biodiversity, chapt 4, pp 19-22.
  • Dias R. K. S., K. R. K. A. Kosgamage, and H. A. W. S. Peiris. 2012. The Taxonomy and Conservation Status of Ants (Order: Hymenoptera, Family: Formicidae) in Sri Lanka. In: The National Red List 2012 of Sri Lanka; Conservation Status of the Fauna and Flora. Weerakoon, D.K. & S. Wijesundara Eds., Ministry of Environment, Colombo, Sri Lanka. p11-19.
  • Dias R. K. S., and K. R. K. Anuradha Kosgamage. 2012. Occurrence and species diversity of ground-dwelling worker ants (Family: Formicidae) in selected lands in the dry zone of Sri Lanka. J. Sci. Univ. Kelaniya 7: 55-72.
  • Dias R. K. S., and R. P. K. C. Rajapaksa. 2016. Geographic records of subfamilies, genera and species of ants (Hymenoptera: Formicidae) in the four climatic zones of Sri Lanka: a review. J. Sci. Univ. Kelaniya 11(2): 23-45.
  • Emery C. 1910. Hymenoptera. Fam. Formicidae. Subfam. Dorylinae. Genera Insectorum 102: 1-34.
  • Forel A. 1901. Les Formicides de l'Empire des Indes et de Ceylan. Part VIII. J. Bombay Nat. Hist. Soc. 13: 462-477
  • Forel A. 1906. Les fourmis de l'Himalaya. Bulletin de la Société Vaudoise des Sciences Naturelles 42: 79-94.
  • Rajan P. D., M. Zacharias, and T. M. Mustak Ali. 2006. Insecta: Hymenoptera: Formicidae. Fauna of Biligiri Rangaswamy Temple Wildlife Sanctuary (Karnataka). Conservation Area Series, Zool. Surv. India.i-iv,27: 153-188.
  • Tiwari R. N. 1999. Taxonomic studies on ants of southern India (Insecta: Hymenoptera: Formicidae). Memoirs of the Zoological Survey of India 18(4): 1-96.
  • Tiwari, R.N. 1999. Taxonomic studies on ants of southern India (Insecta: Hymenoptera: Formicidae). Memoirs of the Zoological Survey of India 18(4):1-96
  • Wilson E. O. 1964. The true army ants of the Indo-Australian area (Hymenoptera: Formicidae: Dorylinae). Pacific Insects 6: 427-483.