Aenictus javanus

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Aenictus javanus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dorylinae
Genus: Aenictus
Species: A. javanus
Binomial name
Aenictus javanus
Emery, 1896

Aenictus javanus casent0281960 p 1 high.jpg

Aenictus javanus casent0281960 d 1 high.jpg

Specimen Labels

All colonies of this species were collected from lowland rainforests.

Identification

Jaitrong & Yamane (2012) - A member of the javanus species group. This species is closely related to Aenictus doydeei, Aenictus longinodus, and Aenictus nishimurai in terms of body size and coloration. Among these species is more closely related to A. longinodus than the others in having the long petiole. A. javanus can be separated from A. longinodus as follows: occipital margin of head in profile angulated, while rounded in A. longinodus; the lateral face of the pronotum that are reticulate but shiny (almost smooth in A. longinodus).

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo, Brunei Darussalam, Indonesia (type locality), Malaysia.
Oriental Region: Thailand, 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 javanus. 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 31-36

Nomenclature

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

  • javanus. Aenictus javanus Emery, 1896f: 245, attributed to Ritsema, fig. (m.) INDONESIA (Java). Forel, 1909d: 222 (w.). See also: Wilson, 1964a: 467; Jaitrong & Yamane, 2012: 57.

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) - HW 0.50 mm, HL 0.55 mm, SL 0.36 mm. Antenna 10-segmented. Mandible narrow, 4-toothed. Clypeal structure as in ceylonicus (q. v.). Parafrontal ridge absent. Occiput feebly convex, lacking a collar. Basal face of propodeum seen from side straight; propodeal junction forming an almost exact right angle. Subpetiolar process an acute tooth which curves posteriorly. Pilosity abundant; length of longest pronotal hairs 0.25 mm.

Head shining. Pronotum mostly shining. Remainder of mesosoma weakly microreticulate and subopaque; but, unlike the condition in ceylonicus, rugae are completely absent. Petiolar dorsum feebly microreticulate and feebly shining; remainder of petiolar more densely reticulate and subopaque to opaque. Postpetiole mostly shining. Color as in ceylonicus.

Jaitrong & Yamane (2012) - Non-type workers from the type locality (n = 8): TL 2.35-2.60 mm; HL 0.55-0.58 mm; HW 0.50-0.53 mm; SL 0.35 mm; ML 0.83-0.88 mm; PL 0.23-0.25 mm; CI 91; SI 67-70.

Head in full-face view slightly longer than broad, subrectangular, with sides convex and posterior margin almost straight or feebly concave; seen in profile occipital corner of head angulated. Antennal scape reaching midlength of head; antennal segment II almost as long as each of III-V; terminal segment longer than VII+VIII+IX and 2.2 times as long as broad. Anterior margin of clypeus bearing 6-7 denticles. Masticatory margin of mandible with 3 acute teeth including a large apical tooth; basal margin lacking denticles. Promesonotum in profile weakly convex dorsally or almost flat and sloping gradually to propodeal junction; in profile propodeum almost flat dorsally; suture between mesopleuron and metapleuron almost absent; propodeal junction angulate, right-angled; declivity of propodeum shallowly concave, encircled by a thin rim. Petiole distinctly longer than high, its dorsal outline slightly elevated posteriorly; subpetiolar process well developed, subrectangular, its ventral border almost straight or feebly concave and as long as posterior border; postpetiole almost as long as, its dorsal outline slightly convex.

Head including antennal scape smooth and shiny; mandible striate along basal margin and smooth in apical and peripheral parts. Dorsal surface of pronotum smooth and shiny, lateral face of pronotum superficially reticulate but shiny; anteriormost part of pronotum microreticulate; mesothorax, metapleuron and propodeum microreticulate. Petiole entirely microreticulate. Postpetiole microreticulate except for a small area on dorsal surface smooth and shiny.

Head and mesosoma dorsally with relatively sparse standing hairs mixed with sparse short hairs; longest pronotal hairs 0.15–0.18 mm long. Head yellowish brown to reddish brown, mesosoma, petiole and postpetiole reddish brown; gaster yellowish brown. Typhlatta spot absent.

Type Material

Jaitrong & Yamane (2012) - Two syntype males from Java, Buitenzorg [Bogor] (Museo Civico di Storia Naturale, Genoa, examined).

References

  • Emery, C. 1896f. Formicides récoltés à Buitenzorg (Java), par M. Massart. Ann. Soc. Entomol. Belg. 40: 245-249 (page 245, fig. male described)
  • Forel, A. 1909i. Ameisen aus Java und Krakatau beobachtet und gesammelt von Herrn Edward Jacobson. Notes Leyden Mus. 31: 221-232 (page 222, worker described)
  • Jaitrong, W. & Yamane, S. (2012) Review of the Southeast Asian species of the Aenictus javanus and Aenictus philippinensis species groups (Hymenoptera, Formicidae, Aenictinae). ZooKeys 193: 49–78, doi: 10.3897/zookeys.193.2768.
  • Wilson, E. O. 1964a. The true army ants of the Indo-Australian area (Hymenoptera: Formicidae: Dorylinae). Pac. Insects 6: 427-483 (page 467, see also)