Aenictus wroughtonii

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Aenictus wroughtonii
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dorylinae
Genus: Aenictus
Species: A. wroughtonii
Binomial name
Aenictus wroughtonii
Forel, 1890

Aenictus wroughtonii casent0907022 p 1 high.jpg

Aenictus wroughtonii casent0907022 d 1 high.jpg

Specimen Labels

No biological information is available for A. wroughtonii. However, judging from the type locality the species probably inhabits lowlands (Jaitrong et al. 2010).

Identification

A. wroughtonii is the smallest species in the wroughtonii group and closely related to Aenictus sagei and Aenictus artipus. (Jaitrong et al. 2010)

Keys including this Species

Distribution

India, from the vicinity of Bombay south to Travancore.

Distribution based on Regional Taxon Lists

Oriental Region: India (type locality).

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 wroughtonii. 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.

Wilson 1964 Army Ant fig 58-63

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • wroughtonii. Aenictus wroughtonii Forel, 1890b: ciii (w.m.) INDIA. See also: Wilson, 1964a: 480; Jaitrong, et al. 2010: 45.

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

Description

Worker

Wilson (1964) - Syntypes: 2 workers selected at random: HW 0.43 mm, HL 0.56 mm, SL 0.51 mm, SI 119; HW 0.43 mm, HL 0.56 mm, SL 0.50 mm, Sl 116. HW of 10 other syntypes 0.43-0.44 mm. Antenna 10-segmented. Mandible typical. Clypeus convex, entire, bearing about 7 prominent teeth on its anterior border. Parafrontal ridge absent. Occiput straight. Propodeal junction evenly rounded. Subpetiolar process virtually absent, consisting of no more than a very low lobe situated under anterior 1/2 of node. Pilosity abundant; length of longest pronotal hairs 0.10 mm.

Entirely shining. Concolorous clear yellow.

Jaitrong et al. (2010) - Worker lectotype and paralectotypes (n = 6): TL 2.5-2.7 mm; HL 0.58-0.60 mm: HW 0.45 mm; SL 0.50-0.55 mm; ML 0.90-0.93 mm; PNW 0.28-0.30 mm; MTL 0.53-0.58 mm; PL 0.23 mm; CI 75-78; SI 111-122.

Head in full-face view subrectangular, elongate, much longer than broad, with weakly convex sides and feebly convex posterior margin. Antennal Scape reaching, posterior margin of head; funicular segments longer than broad: antennal segment II as long as III; IV-VII each shorter than III; VIII-IX broader than II-VII: the last (X) as long as VIII and IX combined. Frontal carina short and thin, not extending beyond the level of posterior margin of torulus. Clypeus short, with very slightly convex anterior margin that bears 8-10 teeth. Mandible with the apical tooth large and curved, followed by 10-12 minute teeth on masticatory margin. Pronotum in profile convex dorsally; promesonotum sloping gradually to metanotal groove. Propodeum slightly longer than promesonotum; its dorsal outline slightly convex; propodeal junction rounded; dec1ivity of propodeum laterally margined with weak ridges. Petiole compressed, as long as high, seen from above almost parallel-sided, seen in profile rounded dorsally and slightly higher behind than in front; subpetiolar process undeveloped, with its ventral outline feebly convex and without anterior angle: postpetiole slightly smaller than petiole with its node rounded dorsally, scarcely longer than broad.

Head including mandible and antennal scape smooth and shiny. Entire mesosoma smooth and very shiny, except upper part of mesopleuron and metapleuron which is finely sculptured. Gaster, femora, and tibiae smooth and shining.

Body with relatively sparse obliquely standing hairs mixed with short hairs over the surface; length of the longest pronotal hair 0.10-0.13 mm. Entire body deep yellow to pale brown, with mandible and posterior portion of gaster often paler.

Type Material

Jaitrong et al. (2010) - Six syntype workers on two pins (three on each pin) from Thana, near Poona, India (Musee d'Histoire Naturelle Genève, examined). The middle specimen mounted on one pin is selected as the lectotype, the others as paralectotypes.

References

  • Forel, A. 1890c. Aenictus-Typhlatta découverte de M. Wroughton. Nouveaux genres de Formicides. Ann. Soc. Entomol. Belg. 34:cii-cxiv. (page ciii, worker, male described)
  • Jaitrong, W., Yamane, S. & Wiwatwitaya, D. 2010. The Army Ant Aenictus wroughtonii and related species in the Oriental region, with descriptions of two new species. Japanese Journal of Systematic Entomology 16: 33-36. PDF
  • 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. PDF
  • Wilson, E. O. 1964a. The true army ants of the Indo-Australian area (Hymenoptera: Formicidae: Dorylinae). Pac. Insects 6: 427-483 (page 480, see also)