Aenictus changmaianus

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Aenictus changmaianus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dorylinae
Genus: Aenictus
Species group: minutulus
Species: A. changmaianus
Binomial name
Aenictus changmaianus
Terayama & Kubota, 1993

Aenictus changmaianus side (www.niaes.affrc.go.jp).jpg

Aenictus changmaianus top (www.niaes.affrc.go.jp).jpg

Specimen labels

No biological information is available for A. changmaianus. However, it has been found in highland seasonal forests (hill evergreen forest) and disturbed areas in northern Thailand (900–1500 m). In eastern Thailand and southern Vietnam it has been collected from lowland seasonal forests (dry evergreen forest), secondary forests, and plantations (160–700 m), thus this species probably ranges from lowland to highland and inhabits both primary and disturbed forests. (Jaitrong & Hashimoto, 2012).

Identification

A member of the minutulus species group. Jaitrong and Hashimoto (2012) - Aenictus changmaianus is very similar in general appearance to Aenictus minutulus and Aenictus minimus. However, A. changmaianus is separated from A. minimus by the dentition on the basal margin of the mandible and antennal scape being relatively longer than in the latter (scape index 67–72 in A. changmaianus; scape index 63–64 in A. minimus). It is distinguished from A. minutulus by the large metapleural gland bulla relatively small in A. minutulus).

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Oriental Region: Cambodia, Thailand (type locality), Vietnam.

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 changmaianus. 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.

Nomenclature

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

  • changmaianus. Aenictus changmaianus Terayama & Kubota, 1993: 68, figs. 2-4 (w.) THAILAND. See also: Jaitrong & Hashimoto, 2012: 31.

Type Material

  • Holotype, worker, Doi Step [Doi Suthep N.P.], Chang Mai Prov. [Chiang Mai Prov.], 1500 m, Thailand, 18 August 1992, M. Terayama and S. Kubota, The National Institute of Agro-Environmental Sciences, Tsukuba, Japan or The National Science Museum, Tsukuba, Japan.
  • Paratype, 3 workers, Doi Step [Doi Suthep N.P.], Chang Mai Prov. [Chiang Mai Prov.], 1500 m, Thailand, 18 August 1992, M. Terayama and S. Kubota, The National Institute of Agro-Environmental Sciences, Tsukuba, Japan and The National Science Museum, Tsukuba, Japan.

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

Description

Worker

Jaitrong and Hashimoto (2012) - Measurements. Paratypes (n = 2): TL 2.00–2.05 mm; HL 0.48–0.50 mm; HW 0.39–0.40 mm; SL 0.28 mm; ML 0.63 mm; PL 0.14 mm; CI 78–84; SI 69–71. Non-type workers (n = 6): TL 1.95–2.60 mm; HL 0.50–0.58 mm; HW 0.38–0.50 mm; SL 0.26–0.35 mm; ML 0.58–0.80 mm; PL 0.13–0.19 mm; CI 75–89; SI 68–72.

Paratypes and non-types - Head in full-face view rectangular, clearly longer than broad, with almost parallel sides and shallowly concaved posterior margin. Antennal scape reaching midlength of head; antennal segment II longer than broad; III–IX each broader than long; terminal segment (X) distinctly longer than broad and 2.1 times as long as broad. Frontal carina very short, not extending beyond the level of posterior margin of torulus. Masticatory margin of mandible with a large apical tooth followed by a medium-sized subapical tooth, 1–4 denticles and a medium-sized basal tooth; basal margin with 2–3 small denticles.Mesosoma seen in profile almost flat or weakly convex dorsally; suture between mesopleuron and metapleuron present; metanotal groove indistinct; metapleural gland bulla large and transparent; distance between propodeal spiracle and metapleural gland bulla shorter than or almost as long as spiracular diameter (Fig. 1D). Propodeal junction obtusely angulated; declivity of propodeum with lateral carinae, but not demarcated basally by a transverse carina. Petiole excluding subpetiolar process almost as long as high, with its dorsal outline convex; subpetiolar process large, rectangular; anterior corner and posterior corner each acutely angulate. Postpetiole higher than long, slightly smaller than petiole and its dorsal outline convex. Femora and tibiae incrassate and widened.

Head including mandible and antennal scape smooth and shiny; promesonotum, dorsa of petiole and postpetiole smooth and shiny; mesopleuron densely reticulate, but shiny; metapleural gland bulla almost smooth and shiny; lateral faces of propodeum, petiole, and postpetiole weakly microreticulate. Legs entirely smooth and shiny.

Head and mesosoma dorsally with relatively dense standing hairs mixed with sparse short hairs over the surface; longest pronotal hair 0.05 mm long. Ground color yellow.

References

  • Jaitrong, W. & Hashimoto, Y. 2012. Revision of the Aenictus minutulus species group (Hymenoptera Formicidae Aenictinae) from Southeast Asia. Zootaxa 3426, 29-44.
  • 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, figs. 2-4 worker described)