Aenictus minutulus

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Aenictus minutulus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dorylinae
Genus: Aenictus
Species group: minutulus
Species: A. minutulus
Binomial name
Aenictus minutulus
Terayama & Yamane, 1989

Aenictus-minutulus-lateral-am-lg.jpg

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Specimen Label

This species has been collected from both primary and disturbed lowland rainforests.

Identification

A member of the minutulus species group. Aenictus minutulus is very similar in general appearance to Aenictus changmaianus and Aenictus minimus (see under Aenictus changmaianus for details).

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

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

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 minutulus. 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.

  • minutulus. Aenictus minutulus Terayama & Yamane, 1989: 601, figs. 7-10 (w.) INDONESIA (Sumatra).

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

Description

Worker

Aenictus minutulus.jpg

Jaitrong and Hashimoto (2012) - Measurements. Paratype workers (n = 2): TL 1.90–1.95 mm; HL 0.45 mm; HW 0.38–0.39 mm; SL 0.25–0.26 mm; ML 0.63 mm; PL 0.15–0.16 mm; CI 83–86; SI 67–68. Non-type workers (n = 10): TL 1.7–2.40 mm; HL 0.43–0.53 mm; HW 0.33–0.48 mm; SL 0.23–0.33 mm; ML 0.55–0.75 mm; PL 0.14–0.20 mm; CI 76–90; SI 65–71.

Paratypes - Head in full-face view rectangular, clearly longer than broad, with almost parallel sides and almost straight or weakly concave posterior margin. Antennal scape reaching midlength of head; antennal segment II longer than broad; III as long as broad; IV–VI each slightly broader than long; VII–IX each as long as broad and III slenderer than IV–VI; terminal segment longer than broad, 2.0 times as long as broad. Frontal carina very short, not extending beyond the level of posterior margin of torulus. Masticatory margin of mandible with a large apical tooth followed by a medium-sized subapical tooth, 1–2 denticles, and medium-sized basal tooth; basal margin with 3–4 small denticles. Mesosoma in profile almost straight dorsally; metanotal groove indistinct; metapleural gland bulla relatively small; distance between propodeal spiracle and metapleural gland bulla clearly longer than spiracular diameter (Fig. 4D). Propodeum in profile with straight dorsal outline; propodeal junction bluntly angulate; declivity of propodeum shallowly concave, seen from back distinctly convergent above, with lateral carinae, but not demarcated basally by a transverse carina. Petiole almost as long as high, with its dorsal outline convex; subpetiolar process large, subretangular, with anterior and posterior corners each acutely angulate. Postpetiole almost as long as petiole, its dorsal outline convex.

Head including mandible and antennal scape smooth and shiny; mesonotum and lateral face of propodeum microreticulate; remainder of mesosoma smooth and shiny. Dorsa of petiole and postpetiole smooth and shiny; lower 1/2 of lateral faces of petiole and postpetiole microreticulate and opaque. Legs entirely smooth and shiny.

Head and mesosoma dorsally with relatively dense standing hairs mixed with sparse short hairs over the surface; longest pronotal hair 0.10 mm long. Ground color light brownish yellow; antennae, legs and gaster yellow.

Type Material

  • Holotype, worker, Pulau Sipora, Mentawai Is., Indonesia, 28 August 1985, Sk. & S. Yamane, Museum Zoologicum Bogoriense, Cibinong, Indonesia or Sk. Yamane Collection at Kagoshima University, Japan.
  • Paratype, 3 workers, Pulau Sipora, Mentawai Is., Indonesia, 28 August 1985, Sk. & S. Yamane, Museum Zoologicum Bogoriense, Cibinong, Indonesia and Sk. Yamane Collection at Kagoshima University, Japan.

References

  • Jaitrong, W. & Hashimoto, Y. 2012. Revision of the Aenictus minutulus species group (Hymenoptera Formicidae Aenictinae) from Southeast Asia. Zootaxa 3426, 29-44.
  • Terayama, M.; Yamane, S. 1989. The army ant genus Aenictus (Hymenoptera, Formicidae) from Sumatra, with descriptions of three new species. Jpn. J. Entomol. 57: 597-603 (page 601, figs. 7-10 worker described)