Aenictus dentatus

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Aenictus dentatus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dorylinae
Genus: Aenictus
Species: A. dentatus
Binomial name
Aenictus dentatus
Forel, 1911

Aenictus dentatus casent0217375 p 1 high.jpg

Aenictus dentatus casent0217375 d 1 high.jpg

Specimen Labels

According to Annette et al. (2003) in Pasoh, Malay Peninsula, Aenictus dentatus foraged on the forest floor in the day and night and preyed on ants of the genus Pheidole. We found this species preying on the ants of the genus Nylanderia in Lambir National Park, Sarawak (SR04-SKY-11). This species occurs from the sea level to highlands (up to 1,300 m a.s.l., Bodong Jaya, southern Sumatra) and inhabits primary and disturbed forests. (Jaitrong, Yamane and Wattanachai 2012)

Identification

A member of the pachycerus group. Jaitrong, Yamane and Wattanachai (2012) - In several characters variation is found that may or may not be of geographic nature. The subpetiolar process varies from low (its ventral outline weakly convex as seen in the Sumatran population and some colonies collected from Borneo such as Eg96-BOR-475, SB96-SKY-26 and SR04-SKY-11) to subtriangular (apex directed down-ward as seen in the type series and some colonies collected from Borneo such as Eg96-BOR-324 and Eg-BOR-545, and the single colony collected by Sk. Yamane from East Kalimantan). Size variation occurs between populations; the specimens from Sumatra are slightly larger than the type series (HW 0.80 - 0.85 mm vs. 0.72 - 0.78 mm). Within the Bornean population the variation in head width is greater: 0.75 mm to 0.88 mm. The specimens collected from Borneo tend to be darker in coloration than the lectotype and the other specimens from Malay Peninsula. However, in most of the characters the specimens from all parts of Sundaland agree with the type series, except for the single colony collected from West Java (FI95-676, SKYC and THNHM), in which the propodeal junction is simply right-angled, in profile not forming a overhanging tooth.

Aenictus paradentatus and Aenictus dentatus are very similar in general appearance as they share the distinctive coarse sculpture on head and mesosoma, and the relatively long antennal scape, extending beyond the posterior margin of the head. However, they differ in several significant characters. The antennal scape is relatively shorter in A. paradentatus (SI 117 - 124) than in A. dentatus (SI 143-152). No overlap is observed in HW / SL between the species. The posterior portion of the head in full-face view is relatively broader in A. paradentatus than in A. dentatus. The first gastral tergite is weakly shagreened with smooth interspaces in the former, while it is wholly smooth and shiny in the latter. The petiole has no peduncle in the former, but has a short but distinct peduncle in the latter.

Keys including this Species

Distribution

India, Malaysia and Borneo.

Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo, Indonesia, Malaysia (type locality).
Oriental Region: India, Thailand.
Palaearctic Region: China.


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 dentatus. 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.

  • dentatus. Aenictus aitkeni var. dentata Forel, 1911d: 383 (w.) WEST MALAYSIA. Raised to species: Wilson, 1964a: 460. See also: Jaitrong, Yamane & Tasen, 2012: 134.

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) - Kuching: HW 0.76 mm, HL 0.92 mm, SL 1.09 mm. Other workers in this series have HW 0.78-0.81 mm. Bombay: HW 0.87 mm, HL L03 mm, SL 1.09 mm. Other workers in this series have HW 0.87-0.88 mm. Antenna 10-segmented. Mandibles typical. Clypeus convex, entire, unarmed. Parafrontal ridge prominent, about 0.5 mm long; prosalient and acutely angular in side view. Occiput convex, with a large, well demarcated collar. Propodeal junction developed into a high, thin transverse ridge which in side view appears as a large, acute "tooth" overhanging the declivitous face. Subpetiolar process a low, irregularly shaped lobe directed downward. Pilosity abundant and long; hairs on pronotum as long as 0.30 mm.

Head, mesosoma, and pedicel entirely microreticulate (reticular diameters about 0.01 mm) and opaque in Kuching series; in the Bombay series, a small area on the gena is feebly shining. In addition, lateral mesosomal surface bearing several longitudinal rugae, 5-6 in the Kuching series and about 10 in the Bombay series. Medium reddish brown overall, except for occiput, which is a somewhat contrasting dark reddish brown.

References

  • Annette, K.F.M., Rosciszewski, K. and Maschwitz, U. 2003. The ant species richness and diversity of a primary lowland rain forest, the Pasoh Forest Reserve, West-Malaysia. In: Okuda, T., Manokaran, N., Matsumoto, Y., Niiyama, K., Thomas, S.C. and Ashton, P.S. (Eds.): Pasoh: Ecology of a lowland rain-forest in Southeast Asia. Springer, Tokyo, pp. 348-373.*Forel, A. 1911f. Fourmis nouvelles ou intéressantes. Bull. Soc. Vaudoise Sci. Nat. 47: 331-400 (page 383, worker described)
  • Jaitrong, W. & Wiwatwitaya, D. 2013. Two new new species of the Aenictus pachycerus species group (Hymenoptera: Formicidae: Aenictinae) from Southeast Asia. Raffles Bulletin of Zoology 61, 97-102.
  • Jaitrong, W., Yamane, S. & Tasen, W. 2012. A sibling species of Aenictus dentatus FOREL, 1911 (Hymenoptera: Formicidae) from continental Southeast Asia. Myrmecological News 16: 133-138.
  • Terayama, M.; Kubota, S. 1993. The army ant genus Aenictus (Hymenoptera: Formicidae) from Thailand and Viet Nam, with descriptions of three new species. Bull. Biogeogr. Soc. Jpn. 48: 68-72 (page 68, record Thailand)
  • Terayama, M.; Yamane, S. 1989. The army ant genus Aenictus (Hymenoptera, Formicidae) from Sumatra, with descriptions of three new species. Jpn. J. Entomol. 57: 597-603 (record in Sumatra)
  • Wilson, E. O. 1964a. The true army ants of the Indo-Australian area (Hymenoptera: Formicidae: Dorylinae). Pac. Insects 6: 427-483 (page 460, raised to species)
  • Xu, Z. 1994a. A taxonomic study of the ant subfamily Dorylinae in China (Hymenoptera Formicidae). J. Southwest For. Coll. 14: 115-122 (page 115, record in China)