Aenictus watanasiti

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

Judging from the known specimens of this species it is distributed from the lowland to highland (300–1100m alt.).

Identification

A member of the ceylonicus group. Jaitrong and Yamane (2013) – Aenictus watanasiti is most similar to Aenictus khaoyaiensis, but the mandible has 3 teeth (4 teeth in the latter) and the subpetiolar process is subrectangular (low, with anteroventral corner acutely angulate and ventral outline feebly convex 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 watanasiti. 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.

  • watanasiti. Aenictus watanasiti Jaitrong & Yamane, 2013: 213, figs. 18A-D (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

(holotype and paratypes, n = 10). TL 2.65–3.05 mm; HL 0.53–0.65 mm; HW 0.50–0.66 mm; SL 0.38–0.50 mm; ML 0.80–1.03 mm; PL 0.20–0.26 mm; CI 96–106; SI 70–79.

Head in full-face view subrectangular, almost as long as broad, sides convex, posterior margin feebly concave. Antennal scape relatively short, slightly extending beyond 1/2 of head length. Frontal carina relatively short, not reaching the level of posterior margin of torulus. Parafrontal ridge incomplete. Anterior clypeal margin feebly concave, concealed by curved anterior extension of frontal carina. Masticatory margin of mandible with 3 teeth, including a large apical tooth; basal margin feebly concave. Maximum width of gap between anterior clypeal margin and mandibles about 2 times as broad as maximum width of mandible. Promesonotum strongly convex dorsally and sloping gradually to metanotal groove; mesopleuron not clearly demarcated from metapleuron; metapleural gland bulla relatively large, its maximum diameter about 3.8 times as long as distance between propodeal spiracle and metapleural gland bulla. Propodeum in profile extremely lower than pronotum and relatively short with weakly convex dorsal outline; propodeal junction angulate; declivity of propodeum broadly and shallowly concave, encircled with a distinct rim. Petiole slightly longer than high, elevated posteriorly; subpetiolar process low and subrectangular, anteroventral corner acutely angulate, but posteroventral corner bluntly angulate. Postpetiole almost as long as petiole, with its dorsal outline roundly convex.

Head entirely smooth and shiny. Mandible very finely striate. Basal 1/3 of antennal scape microreticulate, apical 2/3 smooth and shiny. Promesonotum smooth and shiny except for anteriormost portion reticulate; upper portion of mesopleuron reticulate; lower portion of mesopleuron and propodeum with several longitudinal rugae; metapleuron reticulate. Petiole entirely reticulate; postpetiole reticulate except for dorsal face smooth and shiny. Legs smooth and shiny except basalmost portion of femora and tibiae micropunctate.

Head and mesosoma dorsally with relatively dense standing hairs mixed with decumbent hairs; longest pronotal hair 0.18-0.20 mm long. Head including mandible and antennal scape, mesosoma, petiole, postpetiole, and first gastral tergite dark reddish brown; tip of gaster and gastral sternites, yellowish brown.

Type Material

Holotype. THAILAND: Worker from N. Thailand, Chiang Mai Prov., Muang Dist., 7.VI.2001, leg. W. Jaitrong, WJT01-DST02 (THNHM). Paratypes. Twenty-four workers, same data as holotype (BMNH, MCZC, SKYC, THNHM) and ten workers, same colony as holotype collected by K. Eguchi, Eg01-TH-080 (SKYC, THNHM).

Etymology

The specific name is dedicated to Assoc. Prof. Suparoek Watanasit of Prince of Songkhla University, who has been a leading myrmecologist in Thailand.

References