Aenictus sonchaengi

Aenictus sonchaengi
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Dorylinae
Genus:	Aenictus
Species:	A. sonchaengi
Binomial name
	Aenictus sonchaengi; Jaitrong & Yamane, 2011 Specimen Labels

All material examined of this species was collected from lowland primary rainforests, except for the single colony from Surat Thani Province (southern Thailand) which was collected from a disturbed forest. Two colonies from Khao Nan National Park, southern Thailand, were found during the night, while a colony from Songkhla Province (southern Thailand) was found in early morning. This species is probably sympatric with Aenictus rotundicollis in at least Borneo. (Jaitrong and Yamane 2011)

Identification

A member of the laeviceps species group. This species is closely related to Aenictus rotundicollis in having only 2 long standing hairs on the vertex of the head and the promesonotum which is, seen in profile, strongly convex dorsally and forming a high dome. However, it is easily separated from A. rotundicollis as follows: promesonotum with 2–4 standing hairs (more than 4 hairs in A. rotundicollis); dorsal surface of propodeum smooth and shiny (propodeum entirely sculptured in A. rotundicollis); pronotal dorsum superficially shagreened and shiny and somewhat wrinkled (smooth and shiny in A. rotundicollis). Also see Aenictus breviceps and Aenictus laeviceps.

Keys including this Species

Key to Aenictus laeviceps group species

Distribution

Malay Peninsula (S. Thailand) and Borneo (Sarawak and Brunei).

Distribution based on Regional Taxon Lists

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

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.

Biology

Explore Overview of Aenictus biology

Little is known about the biology of Aenictus sonchaengi. 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.

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Castes

Known only from the worker caste.

Nomenclature

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

sonchaengi. Aenictus sonchaengi Jaitrong & Yamane, 2011: 43, figs. 38-40 (w.) THAILAND, BORNEO (East Malaysia: Sarawak; Brunei).
- Type-material: holotype worker, 14 paratype workers.
- Type-locality: holotype Thailand: Nakon Si Thammarat Prov., Khao Nan, 12.xii.2007 (W. Jaitrong); paratypes with same data.
- Type-depositories: TNHM (holotype); BMNH, SKYC, TNHM (paratypes).
- Status as species: Khachonpisitsak, et al. 2020: 31.
- Distribution: Brunei, Malaysia (Sarawak), Thailand.

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

Description

Worker

Measurements. Holotype and paratypes (n = 10): TL 4.20–4.35 mm; HL 0.85–0.95 mm; HW 0.83–0.85 mm; SL 0.68–0.73 mm; ML 1.33–1.35 mm; PL 0.30–0.33 mm; CI 89–97; SI 82–85.

Holotype and paratypes -Head in full-face view subrectangular, slightly longer than broad, with sides convex and posterior margin almost straight; occipital carina complete. Antennal scape relatively short, only reaching 3/4 of head length; antennal segments II–X each longer than broad; II almost as long as each of III–V; terminal segment (X) slightly shorter than VII+VIII+IX. Frontal carina short, slightly extending beyond posterior margin of torulus. Anterior margin of clypeus slightly convex, bearing 5–6 denticles. Masticatory margin of mandible with a large apical tooth followed by a medium-sized subapical tooth, 5 denticles, and a medium-sized basal tooth; basal margin bearing 2–3 denticles. Mesosoma rather stout; promesonotum in profile strongly convex and forming a dome, mesonotum sloping to metanotal groove; propodeum distinctly lower than promesonotum, with its dorsal outline almost straight; propodeal junction round or weakly angulate; declivity seen in profile almost vertical, not margined dorsally and laterally with a carina. Petiole relatively short, globular, almost as long as high; subpetiolar process well developed and triangular, its apex directed downward and backward; postpetiole slightly larger than petiole.

Entire head smooth and shiny. Mandible very finely striate except along masticatory and outer margins. Antennal scape superficially sculptured and shiny. Pronotum entirely smooth and shiny except for its anteriormost portion being punctate; mesonotum and upper portion of mesopleuron longitudinally rugulose; remainder of mesopleuron, metapleuron and lateral face of propodeum punctate; dorsal surface of propodeum smooth and shiny. Petiole densely reticulate; postpetiole dorsally smooth and shiny, its lateral face weakly reticulate. Legs entirely smooth and shiny.

Vertex with a pair of standing hairs; promesonotum with relatively sparse standing hairs; longest pronotal hair 0.20–0.23 mm long; propodeum with a pair of standing hairs near posterolateral corners. Entire body dark reddishbrown. Typhlatta spot located anterior to occipital corner.

Type Material

Holotype worker from S. Thailand, Nakon Si Thammarat Prov., Khao Nan, 12 XII 2007, W. Jaitrong leg. (Natural History Museum of the National Science Museum). Fourteen paratype workers, same data as holotype (The Natural History Museum, SKY Collection, THNHM).

Etymology

The specific name is dedicated to Dr. Pichai Sonchaeng, the president of the National Science Museum, Thailand.

References

Jaitrong, W. & Yamane, S. 2011. Synopsis of Aenictus species groups and revision of the A. currax and A. laeviceps groups in the eastern Oriental, Indo-Australian, and Australasian regions (Hymenoptera: Formicidae: Aenictinae). Zootaxa, 3128, 1–46.
Khachonpisitsak, S., Yamane, S., Sriwichai, P., Jaitrong, W. 2020. An updated checklist of the ants of Thailand (Hymenoptera, Formicidae). ZooKeys 998, 1–182 (doi:10.3897/zookeys.998.54902).
Yamane, S., Tanaka, H.O., Hasimoto, Y., Ohashi, M., Meleng, P., Itioka, T. 2021. A list of ants from Lambir Hills National Park and its vicinity, with their biological information: Part II. Subfamilies Leptanillinae, Proceratiinae, Amblyoponinae, Ponerinae, Dorylinae, Dolichoderinae, Ectatomminae and Formicinae. Contributions from the Biological Laboratory, Kyoto University 31, 87–157.

References based on Global Ant Biodiversity Informatics

Borowiec M. L. 2016. Generic revision of the ant subfamily Dorylinae (Hymenoptera, Formicidae). ZooKeys 608: 1–280.
Jaitrong W. 2015. A revision of the Thai species of the ant genus Aenictus Shuckard, 1840 (Hymenoptera: Formicidae: Dorylinae). The Thailand Natural History Museum Journal 9(1): 1-94.
Jaitrong W.; Yamane, S. 2011. Synopsis of Aenictus species groups and revision of the A. currax and A. laeviceps groups in the eastern Oriental, Indo-Australian, and Australasian regions (Hymenoptera: Formicidae: Aenictinae). Zootaxa 3128:1-46.