Aenictus rotundicollis

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

Aenictus rotundicollis is likely sympatric with the similar Aenictus sonchaengi and inhabits lowland rainforests. It is presently only known from Borneo.

Identification

A member of the laeviceps species group. Very similar to Aenictus sonchaengi in having only 2 long standing hairs on the vertex of the head and the dorsally strongly convex promesonotum which forms a high dome. See A. sonchaengi and also identification notes for Aenictus breviceps and Aenictus laeviceps. (Jaitrong and Yamane 2011)

Keys including this Species

• Key to Aenictus laeviceps group species

Distribution

Known from Borneo (Sabah, Sarawak, and Brunei).

Distribution based on Regional Taxon Lists

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

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 rotundicollis. 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.

• rotundicollis. Aenictus rotundicollis Jaitrong & Yamane, 2011: 41, figs. 41-43 (w.) BORNEO (East Malaysia: Sarawak, Sabah; Brunei).
  • Type-material: holotype worker, 21 paratype workers.
  • Type-locality: holotype Malaysia: Sarawak, Niah N.P., 28.i.1993 (Sk. Yamane); paratypes with same data.
  • Type-depositories: FRCK (holotype); BMNH, MBSM, MCZC, SKYC, TNHM (paratypes).
  • Distribution: Brunei, Malaysia (Sabah, Sarawak).

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 4.15–4.25 mm; HL 0.85–0.90 mm; HW 0.80–0.85 mm; SL 0.68–0.73 mm; ML 1.30–1.35 mm; PL 0.28–0.30 mm, CI 94–95; SI 84–85.

Holotype and paratypes - Head in full-face view rounded, almost as long as broad, with sides strongly convex and posterior margin almost straight or weakly convex; occipital carina complete. Antennal scape relatively short, not reaching posterolateral corner of head; antennal segments II–X each longer than broad; II almost as long as each of III–V; terminal segment (X) almost as long as VII+VIII+IX. Frontal carina short, extending slightly 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, 4 denticles, and a small basal tooth; basal margin bearing 2–3 small teeth. Mesosoma relatively 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 roundly angulate; declivity in profile vertical and almost straight, without any trace of dorsal and lateral carinae. Petiole relatively short, almost as long as high and slightly shorter than postpetiole; subpetiolar process well developed and subtriangular, its apex directed downward and backward; postpetiole almost as long as high, dorsum of node more rounded than in petiole.

Entire head smooth and shiny. Sculpture of mandible very fine, not typically striate as seen in other species; the sculpture also covering outer zone, and only apical and masticatory zones smooth. Antennal scape superficially reticulate and shiny. Pronotum smooth and shiny, with its anteriormost portion punctate; mesonotum longitudinally rugulose; mesopleuron, metapleuron and propodeum entirely punctate. Petiole densely punctate; postpetiole shagreened with smooth and shiny interspaces.

Head with a pair of standing hairs on vertex; promesonotum with 2–3 standing hairs. Entire body dark reddishbrown. Typhlatta spot well developed, located anterior to occipital corner.

Type Material

Holotype worker from Malaysia, Sarawak, Niah N.P., 28 I 1993, Sk. Yamane leg (Forest Research Center). Twenty-one paratype workers, same data as holotype (The Natural History Museum, Museum of Comparative Zoology, SKY Collection, Natural History Museum of the National Science Museum, Universiti Malaysia Sabah).

Etymology

The specific name is a noun describing the roundly raised promesonotum.

References

• Borowiec, M.L. 2019. Convergent evolution of the army ant syndrome and congruence in big-data phylogenetics. Systematic Biology 68, 642–656 (doi:10.1093/sysbio/syy088).
• 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.

References based on Global Ant Biodiversity Informatics

• 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.