Aenictus glabratus

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Aenictus glabratus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dorylinae
Genus: Aenictus
Species: A. glabratus
Binomial name
Aenictus glabratus
Jaitrong & Nur-Zati, 2010

The type series was collected by sifting from the leaf litter in a lowland rainforest in Malay Peninsula.

Identification

A member of the silvestrii species group. A. glabratus is a distinct species in having the head almost smooth and shiny and the body much paler (clear yellow or yellowish brown) and smaller than in the other species of the A. silvestrii-group.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: Malaysia (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 glabratus. 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.

  • glabratus. Aenictus glabratus Jaitrong & Nur-Zati, 2010: 450, figs. 1-3 (w.) WEST MALAYSIA.

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 = 7): TL (total length) 2.85- 2.95 mm; HL (head length) 0.63-0.65 mm; HW (head width) 0.48-0.53 mm; SL (scape length) 0.33-0.38 mm; ML (mesosomal length) 0.83-0.85 Jaitrong, W. & A.M. Nur-Zati — A New Species of Aenictus From Malay Peninsula 451 mm; MTL (maximum length of mid tibia) 0.30-0.38 mm; PL (petiole length) 0.20-0.23 mm; CI (cephalic index = HW/HL × 100) 76-81; SI (scape index = SL/HW × 100) 67-71.

(holotype and paratypes). Head in full-face view rectangular, distinctly longer than broad, with almost parallel sides; posterior margin of head almost straight but weakly sinuate; occipital margin concave bearing a carina. Antenna 9-segmented; scape short, extending to the midlength of head in full-face view; antennal segment II longer than III and IV; V-IX, each longer than broader; terminal segment (IX) very large, almost as long as VI, VII and VIII combined. Frontal carinae short extending less than half length of head, very poorly developed in posterior half. Clypeus short and roundly produced anteriorly, lacking teeth on anterior margin. Mandible with apical tooth large, followed by 10-12 denticles of two sizes, the larger alternating with 1-3 smaller; basal margin of mandible with 1-2 denticles near basal angle.

With mesosoma seen in proile promesonotum weakly convex dorsally and sloping gradually to metanotal groove; propodeum slightly lower and weakly convex dorsally; mesopleuron not clearly demarcated from metapleuron. Propodeal junction angulated; declivity of propodeum shallowly concave, encircled with a rim.

Petiole almost as long as high, anteriorly margined by a transverse carina, while posterior lacking it; subpeiolar process subtriangular, its apex directed downward; postpetiole slightly smaller than petiole, roundly convex dorsally, anteroventrally produced as a blunt angle directed downward and forward. Gaster elongate-elliptical, narrowed anteriorly and posteriorly. Head entirely smooth and shiny except anteriormost portion of head in pro"le where short irregular longitudinal rugae are present; area around antennal sockets with dense punctures; upper face of antennal scape basally with dense micropunctures and apically much smoother; mandible largely with dense minute punctures, but smooth apically and along masticatory margin. Dorsal surface of mesosoma weakly and irregularly corrugated but shiny; anteriormost portion of pronotum punctate; sides of pronotum smooth and shiny; mesopleuron, metapleuron and sides of proprodeum densely punctate. Gaster smooth and shiny except for extreme basal portion. Femora and tibiae smooth and shiny.

Body with relatively sparse standing hairs mixed with sparse short hairs over the surface; length of the longest pronotal hair approximately 0.13–0.15 mm. Head, mesosoma and waist yellowish brown; gaster and legs clear yellow; mandible dark brown.

Type Material

Holotype. Worker from Selangor, Semangkok Forest Reserve. (550 m alt.), Malaysia, Nur-Zati et al. leg., 21 XI 2007, WSM0167.03. Paratypes. Six workers, same data as holotype. Type depository. The holotype and one paratype are deposited in the Forest Research Institute Malaysia (Malaysia) and some paratypes in the Natural History Museum, London, (U.K.), SKY collection at Kagoshima University (Japan), the Natural History Museum of the National Science Museum (Thailand).

Etymology

The species epithet “glabratus” is a Latin word meaning smooth. This refers to the smooth and shiny head of this species, while the head is entirely sculptured in the other species of the A. silvestrii-group.

References

Jaitrong, W. & Nur-Zati, A.M. (2010) A new species of the ant genus Aenictus (Hymenoptera: Formicidae: Aenictinae) from the Malay Peninsula. Sociobiology, (2)56, 449-454.