Aenictus wilaiae

Aenictus wilaiae
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Dorylinae
Genus:	Aenictus
Species:	A. wilaiae
Binomial name
Aenictus wilaiae Jaitrong & Yamane, 2013

This species mainly inhabits lowland primary forests. W. Jaitrong observed this species preying on other ants (HKK10-06-03; Monomorium pharaonis) and termites (HKK10-06-03) in Thailand.

Identification

A member of the ceylonicus group. Jaitrong and Yamane (2013) – Aenictus wilaiae is most similar in general appearance to Aenictus pilosus. However, it is separated from the latter by the following characteristics: promesonotum in profile weakly convex (strongly convex, forming a dome in the latter); propodeum in profile with feebly convex dorsal outline (clearly straight in the latter); petiole sessile with low node, its posterior face encircled with a thin carina (not encircled with a carina in the latter); ventral margin of subpetiolar process convex (concave in the latter); postpetiole almost as long as petiole (slightly longer in the latter); body smaller.

Keys including this Species

• Key to southeastern Asian Aenictus ceylonicus group species

Distribution

Distribution based on Regional Taxon Lists

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 wilaiae. 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 Online Catalogue of the Ants of the World.

• wilaiae. Aenictus wilaiae Jaitrong & Yamane, 2013: 215, fig. 19A-C (w.) THAILAND.
  • Type-material: holotype worker, 33 paratype workers.
  • Type-locality: holotype Thailand: Chachoengsao Prov., Thatakiab Dist., 29.v.2005, WJT05-E202 (W. Jaitrong); paratypes with same data.
  • Type-depositories: TNHM (holotype); BMNH, MCZC, SKYC, TNHM (paratypes).
  • Distrbution: Thailand.

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

Description

Worker

(holotype and paratypes, n = 10). TL 2.10–2.55 mm; HL 0.53–0.55 mm; HW 0.50–0.53 mm; SL 0.36–0.39 mm; ML 0.75–0.83 mm; PL 0.18–0.23 mm; CI 95–100; SI 71–74.

Head in full-face view subrectangular, slightly longer than broad, sides weakly convex and posterior margin almost straight or feebly concave. Antennal scape relatively short, not reaching 2/3 of head length. Frontal carina slightly extending beyond the level of posterior margin of torulus. Parafrontal ridge absent. Anterior clypeal margin almost straight, lacking denticles and partly concealed by curved anterior extension of frontal carina. Masticatory margin of mandible with a large acute apical tooth followed by a medium-sized sub-apical tooth, 2 denticles, and a medium-sized basal tooth; basal margin feebly concave. Maximum width of gap between anterior clypeal margin and mandibles about 1.8 times as broad as maximum width of mandible. Promesonotum convex dorsally and sloping gradually to metanotal groove; mesopleuron not clearly demarcated from metapleuron; metapleural gland bulla relatively small, its maximum diameter about 2 times as long as distance between propodeal spiracle and metapleural gland bulla. Propodeum in profile with almost straight or feebly concave dorsal outline, sloping gradually to propodeal junction; propodeal junction nearly right-angled; declivity of propodeum shallowly concave, and encircled with a distinct rim. Petiole almost as long as high, with its dorsal outline slightly elevated posteriorly; subpetiolar process generally very low, with its anteroventral corner angulate and ventral margin convex. Postpetiole almost as long as petiole, with its dorsal outline convex.

Head entirely smooth and shiny. Mandible very finely striate. Antennal scape superficially microreticulate, but shining. Promesonotal dorsum smooth and shiny except for anteriormost portion punctate, lateral face of pronotum superficially micro-reticulate and shiny; mesopleuron, metapleuron, and propodeum entirely reticulate except for metapleuron partly smooth and shiny; in addition, mesopleuron with longitudinal rugae; lateral face of propodeum with 2-3 short longitudinal rugae. Petiole and postpetiole densely punctate. Legs entirely smooth and shiny.

Head and mesosoma dorsally with relatively dense standing hairs; longest pronotal hair 0.10–0.13 mm long. Head, gaster, and legs yellowish brown; mesosoma, petiole, and postpetiole reddish brown; mandible reddish brown.

Type Material

Holotype. THAILAND: Worker from E. Thailand, Chachoengsao Prov., Thatakiab Dist., 29.V.2005, leg. W. Jaitrong, WJT05-E203 (THNHM). Paratypes. Thirty-three workers, same data as holotype (BMNH, MCZC, SKYC, THNHM).

Etymology

The specific name is dedicated to the late Mrs Wilai Jaitrong, the great mother of the first author.

References

• Dhadwal, T., Bharti, H. 2023. Aenictus dirangensis sp. nov. (Hymenoptera: Formicidae), a new species of Aenictus ceylonicus group from India. Journal of the Entomological Research Society 25(2): 387-403 (doi:10.51963/jers.v25i2.2367).
• Jaitrong, W. & Yamane, S. 2013. The Aenictus ceylonicus species group (Hymenoptera, Formicidae, Aenictinae) from Southeast Asia. Journal of Hymenoptera Research 31:165-233.
• 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).

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., and S. Yamane. 2013. The Aenictus ceylonicus species group (Hymenoptera, Formicidae, Aenictinae) from Southeast Asia. Journal of Hymenoptera Research 31: 165-233.