Aenictus thailandianus

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

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

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

Specimen labels

Nothing is mentioned by Terayama and Kubota (1993) about the bionomics of A. thailandianus. However, judging from the type series and non-type specimens examined this species mainly inhabits highlands (1000–1500m alt.) in both primary and secondary forests (Jaitrong & Yamane, 2013).

Identification

A member of the ceylonicus group. Jaitrong and Yamane (2013) – Aenictus thailandianus is most similar to Aenictus cylindripetiolus in having the mandible with more than 4 teeth and entirely sculptured promesonotum. However, it can be separated from the latter by the following characteristics: Pronotum entirely punctate (reticulate in the latter); petiole almost as long as postpetiole, with high node (distinctly longer than high in the latter); femora superficially sculptured (punctate, shagreened or partly reticulate) (entirely smooth and shiny except basalmost portion micropunctate in the latter); body larger (TL 3.30–3.50 mm, HW 0.65–0.73 mm in the former; TL 2.90–3.15 mm, HW 0.60–0.65 mm in the latter).

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

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

Worker

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.

  • thailandianus. Aenictus thailandianus Terayama & Kubota, 1993: 71, figs. 11-13 (w.) THAILAND.

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 Yamane (2013) - (paratypes, n = 6). TL 3.33–3.50 mm; HL 0.68–0.78 mm; HW 0.65–0.73 mm; SL 0.50–0.58 mm; ML 1.10–1.23 mm; PL 0.28–0.33 mm CI 93–96; SI 77–81.

Head in full-face view slightly longer than broad, sides convex, posterior margin almost straight and occipital corner roundly angulate; occipital margin bearing a carina. Antennal scape relatively long, extending beyond 2/3 of head length but not reaching posterolateral corner of head. Frontal carina relatively long and distinct, extending beyond the level of posterior margin of torulus. Parafrontal ridge indistinct, slightly extending beyond the level of posterior margin of torulus. Anterior clypeal margin almost straight or feebly concave, its lateral portions forming blunt angle. Masticatory margin of mandible with a large acute apical tooth followed by a medium-sized subapical tooth, 8 denticles, and a medium-sized basal tooth; basal margin straight, lacking denticle. Maximum width of gap between anterior clypeal margin and mandibles about 1.5 times as broad as maximum width of mandible. Promesonotum strongly convex dorsally and sloping gradually to metanotal groove; metanotal groove indistinct or almost absent; mesopleuron relatively short and clearly demarcated from metapleuron by a deep groove; mesonotum demarcated from mesopleuron by a conspicuous ridge; metapleural gland bulla relatively large, its maximum diameter about 3 times as long as distance between propodeal spiracle and metapleural gland bulla. Propodeum in profile with weakly convex dorsal outline; propodeal junction angulated, overhanging the declivitous face of propodeum; the declivity narrowly and shallowly concave, encircled with a thin rim. Petiole almost as long as high, its node with dorsal outline elevated posteriorly; subpetiolar process low, with forward-directed lobe whose ventral margin is straight or feebly concave. Postpetiole slightly shorter than petiole, with its dorsal outline convex.

Head and gaster entirely smooth and shiny. Mandible very finely striate. Antennal scape entirely punctate. Mesosoma, petiole, and postpetiole strongly reticulate. Lateral face of pronotum partly smooth or superficially reticulate; mesopleuron and lateral face of propodeum with relatively irregular longitudinal rugae. Legs weakly microreticulate except for smooth coxae.

Head and mesosoma dorsally with relatively dense standing hairs; longest pronotal hair 0.30–0.33 mm long. Antennal scape, mesosoma, petiole and postpetiole reddish brown; head, gaster and legs yellowish brown.

Type Material

Jaitrong and Yamane (2013) - Holotype and 39 paratype workers (NAIST, SKYC) from N. Thailand, Chang Mai [Chiang Mai], Doi Step [Doi Suthep-Pui N.P.], ca. 1500 m alt. Six paratype workers (SKYC) were examined.

References

  • Liu, C.; Guénard, B.; Hita Garcia, F.; Yamane, S.; Blanchard, B.; Yang, D.-R.; Economo, E. 2015. New records of ant species from Yunnan, China. ZooKeys 477:17-78.
  • 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 71, figs. 11-13 worker described)