Aenictus currax

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Aenictus currax
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dorylinae
Genus: Aenictus
Species: A. currax
Binomial name
Aenictus currax
Emery, 1900

Aenictus currax casent0903748 p 1 high.jpg

Aenictus currax casent0903748 d 1 high.jpg

Specimen Labels

Wilson (1964) reported on a colony of Aenictus currax: "The Karema (Papua New Guinea) colony was found on the morning of March 9 or 10, 1955, on the open floor of virgin lowland rain forest. It consisted of a packed mass of workers, which must have numbered at least 100,000, collected around the base of a small spiny palm tree. The mass extended up the trunk to about 1 m. The colony was apparently entirely above ground. When it was knocked onto a ground cloth and scattered, the queen and brood were easily collected. The colony was evidently in the nomadic phase. The queen's abdomen was not enlarged, i. e., the gastric sclerites overlapped; and the brood consisted mostly of mature larvae, nearly as long as a worker, together with a few smaller larvae and prepupae. Although no raids were being conducted at time, the workers were carrying bodies of adult workers and && of an unidentified species of Crematogaster. The currax workers were not at all aggressive when disturbed. They dispersed rapidly over the forest floor and rarely attempted to sting my hands as I handled them., the morning of March 1955, on the open floor of a virgin lowland rainforest. It consisted of a packed mass of workers, which must have numbered at least 100,000. The workers extended up the tree trunk to about 1 m. The colony was apparently entirely above ground, and the workers were carrying bodies of adult workers and males of the ant genus Crematogaster.

Identification

A member of the currax group. Jaitrong and Yamane (2011) - Aenictus currax is very similar in general appearance to Aenictus diclops, Aenictus huonicus, Aenictus pfeifferi, Aenictus parahuonicus and Aenictus wayani. Among these this species is more closely related to A. diclops and A. wayani than to the others in having a slender mesosoma and relatively long antennal scape (SI 97–104, while SI is less than 95 in A. pfeifferi, A. huonicus, and A. parahuonicus). Aenictus currax can be separated from A. diclops by having the propodeal and petiolar dorsa smooth and shiny (entirely sculptured in A. diclops), and it is easily distunguished from A. wayani as follows: antennal scape relatively longer (SI 104 in A. currax, 97–100 in A. wayani); basal margin of mandible sinuate with 3–4 ill-defined denticles in A. currax (denticles absent in A. wayani). All the species mentioned above are completely allpatric.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: New Guinea.

Check distribution from AntMaps.

Distribution based on specimens

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The above specimen data are provided by AntWeb. Please see Aenictus currax for further details

Biology

Little is known about the biology of Aenictus currax. 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.

  • currax. Aenictus currax Emery, 1900c: 310, pl. 8, fig. 1 (w.) NEW GUINEA. See also: Wilson, 1964a: 459; Jaitrong & Yamane, 2011: 13.

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

Wilson 1964 Army Ant fig 21-30

Description

Worker

Jaitrong and Yamane (2011) - Measurements. lectotype: TL 4.15 mm; HL 0.88 mm; HW 0.70 mm; SL 0.73 mm; ML 1.33 mm; PL 0.30 mm; CI 80; SI 104.

(lectotype and non-type specimens). Head in full-face view distinctly longer than broad, with sides slightly convex and posterior margin feebly concave; occipital margin bearing a distinct carina. Antenna relatively thick; scape not reaching posterolaterial corner of head; antennal segments II–X each longer than broad, but V–VIII rather short; II slightly longer than each of III–VI. Frontal carina short, slightly extending beyond the level of posterior margin of torulus. Parafrontal ridge short. Masticatory margin of mandible with a large apical tooth followed by a medium-sized subapical tooth and 4–6 denticles; basal margin of mandible sinuate with 3–4 ill-defined denticles. Mesosoma elongate; promesosoma in profile convex dorsally and sloping gradually to metanotal groove; mesopleuron clearly demarcated from metapleuron by a groove. Propodeum in profile with moderately convex (in smaller specimens almost flat) dorsal outline; propodeal junction obtusely angulate; declivity of propodeum shallowly concave and encircled with a thin rim; area below propodeal spiracle distinctly impressed; distance between propodeal spiracle and metapleural gland bulla almost as long as spiracular diameter; the spiracle clearly circular, in diameter about 2.5 times as long as postpetiolar spiracle. Petiole distinctly longer than high, with its dorsal outline convex; subpetiolar process reduced, low, anteriorly right-angulate. Postpetiole round, almost as long as high.

Wilson 1964 Army Ant fig 84-89

Head including mandible and antennal scape extensively smooth and shiny; basal 1/3 of scape superficially sculptured. Pronotum smooth and shiny except for the anteriormost portion which is punctate; mesonotum smooth and shiny; mesopleuron macroreticulate, with several short longitudinal rugulae; propodeum bearing scattered, thin, straight longitudinal rugae, whose interspaces are smooth and shiny. Petiole smooth and shiny dorsally, its anterior portion, lateral faces and posterior portion punctate. Postpetiole entirely smooth and shiny except for anteriormost portion which is punctate. Legs smooth and shiny.

Body with relatively sparse standing hairs; longest pronotal hair 0.23–0.25 mm long. Entire body brownishyellow except for a much darker median area from upper frons to vertex between large typhlatta spots occupying the occipital corner; basal 1/3 of antennal scape also darker.

Type Material

References

  • Emery, C. 1900b. Formicidarum species novae vel minus cognitae in collectione Musaei Nationalis Hungarici quas in Nova-Guinea, colonia germanica, collegit L. Biró. Publicatio secunda. Térmeszetrajzi Füzetek. 23: 310-338 (page 310, pl. 8, fig. 1 worker described)
  • 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). Pacific Insects. 6: 427-483 (page 459, see also)