Aenictus yamanei

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Aenictus yamanei
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dorylinae
Genus: Aenictus
Species: A. yamanei
Binomial name
Aenictus yamanei
Wiwatwitaya & Jaitrong, 2011

Aenictus-yamanei-lateral-am-lg.jpg

Aenictus-yamanei-dorsal-am-lg.jpg

Paratype Specimen Label

Aenictus yamanei, together with its close relative Aenictus hottai, are the only members of the A. hottai species group. Both are probably restricted to Sundaland (south-east Asia) and inhabit lowland primary rainforests.

Identification

A member of the hottai species group.

Wiwatwitaya and Jaitrong (2011) - For discrimination of this species from Aenictus hottai, see below and under A. hottai. The workers of two colonies collected from West Malaysia (MG103 and FI92MT-10) are slightly smaller and brighter than those of the type series.

  • Larger species (HW 0.93-1.00 mm; ML 1.63-1.75 mm); head relatively shorter (CI 88-91) . . . . . Aenictus hottai
  • Smaller species (HW 0.63-0.70 mm; ML 1.22-1.27 mm); head relatively longer (CI 79-85) . . . . . Aenictus yamanei

Key to Aenictus species groups

Distribution

Malay Peninsula (Malaysia) and Borneo (Sarawak).

Distribution based on Regional Taxon Lists

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

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Wiwatwitaya and Jaitrong (2011) - A. yamanei is sympatric with A. hottai in at least Ulu Gombak, Malay Peninsula. All colonies of A. yamanei were collected from the forest floor in the lowland primary forest. So far we have no information about its prey.

Little is known about the biology of Aenictus yamanei. 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.

  • yamanei. Aenictus yamanei Wiwatwitaya & Jaitrong, 2011: 562, figs. 2A-D, 3 (w.) BORNEO.

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

Description

Worker

Holotype and paratype workers (n = 10): TL 3.70-3.80 mm; HL 0.83-0.85 mm; HW 0.63-0.70 mm; SL 0.68-0.73 mm; ML 1.22-1.27 mm; PL 0.32-0.35 mm; CI 79-85; SI 96-103.

(holotype and paratypes). Head in full-face view clearly longer than broad, with sides feebly convex and posterior margin almost straight or feebly concave. Head from the tip of frontal carina to occipital margin longitudinally and very shallowly impressed. Antennal scape extending posteriorly beyond 3/4 of headlength. Frontal carina not reaching midlength of head, and well developed anteriorly and poorly developed posteriorly; parafrontal ridge present extending posteriorly by less than 1/3 of head length; in profile its anteriormost part raised as a subtriangular process, and poorly developed posteriorly. Clypeus short, its anterior margin convex, lacking denticles. Mandible broad and triangular, its masticatory margin with a large apical tooth followed by a small subapical tooth and a series of about 19-20 minute denticles of two sizes, the larger alternating with 4-6 smaller; basal margin of mandible lacking denticles. Mososoma relatively stout; promesonotum seen in profile strongly convex dorsally and sloping gradually to metanotal groove; mesopleuron clearly demarcated from metapleuron by a deep groove; anepisternum clearly demarcated from katepisternum by a deep groove. Propodeum in profile with almost striagth dorsal outline; propodeal junction acutely angulate; declivity of propodeum shallowly concave, and encircled with a rim; opening of propodeal spiracle clearly circular with its diameter about 2.3 times as long as diameter of postpetiolar spiracle. Petiole slightly longer than high, its dorsal outline elevated posteriorly, posterior face of petiole shallowly concave, and encircled with a carina; subpetiolar process large with anterior corner rounded, posteroventrally produced into an arm with a blunt tip; margin connecting anterior corner and the tip of the arm almost straight. Postpetiole clearly longer than petiole, its dorsal outline roundly convex.

Head, mesosoma, petiole, and postpetiole densely punctate and opaque; antennal scape micropunctate; mandible extensively puncto-striate, with outer zone, apical portion and masticatory margin rather smooth and shiny. Proprodeal dorsum with a few short longitudinal ridges in front of junction. Gastral segment I with fine and superficial reticulation, subopaque and slightly shining. Punctation on femora weaker than on head and mesosoma; tibiae of legs entirely micropunctate.

Head with a pair of long standing hairs mixed with relatively dense short hairs over the surface; mesosoma with relatively sparse long standing hairs mixed with dense short hairs over the surface; length of the longest pronotal hair 0.38-0.40 mm. Entire body dark reddish-brown.

Type Material

Holotype. Worker from Niah N. P., Sarawak, Borneo, Malaysia, 9 I 1993, Sk. Yamane leg. (Forest Research Center). Nine paratype workers, same data as holotype (Ant Museum, SKY Collection and Natural History Museum of the National Science Museum).

Etymology

The specific name is dedicated to Prof. Seiki Yamane of Kagoshima University, Japan.

References