Aenictus sagei

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Aenictus sagei
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dorylinae
Genus: Aenictus
Species: A. sagei
Binomial name
Aenictus sagei
Forel, 1901

Aenictus sagei casent0281958 p 1 high.jpg

Aenictus sagei casent0281958 d 1 high.jpg

Specimen Labels

Jaitrong et al. (2010) - Aenictus sagei is known from the type series from Dharmasala (Forel, 1901), and additional material collected in Solon [?Solan] (1,380-1,400 m alt.), north-central India by L. Weatherill who observed workers preying on other small ants such as Paratrechina and Plagiolepis (Wilson, 1964). These prey ants are in size almost the same as the prey of A. camposi observed in Malay Peninsula reported by Rosciszewski and Maschwitz (1994).

Pisarski (1967) also notes that numerous specimens were collected by Dr. Knut Lindberg (1892 - 1962, Lund, Sweden) from Tour Kham [?Torkham], on the border with Pakistan, in the vicinity of Peshawar, Afghanistan.

Identification

A member of the wroughtonii group. This hairy species is closely related to Aenictus wroughtonii, but is slighty larger than the latter. The pronotal hairs are longer in A. sagei (0.20-0.25 mm) than in A.wroughtonii (0.10-0.13 mm). The antennal scape is short, shorter than head length with SI 100 in the former, while it reaches posterior margin of head with SI 111-122 in the latter. The subpetiolar process is weakly developed, with its anteroventral corner obtusely angulate in the former, while it is almost absent and unarmed in the latter. Aenictus sagei is also similar to Aenictus artipus, in which, however, the subpetiolar process is recognizable, with its anteroventral corner more clearly angulated. The antennal scape is longer in A. artipus (extending beyond posterolateral corner of head), while it does not exceed the posterior corner in A. sagei. (Jaitrong et al. 2010)

Keys including this Species

Distribution

North-central India

Distribution based on Regional Taxon Lists

Oriental Region: India (type locality), Nepal.
Palaearctic Region: Afghanistan.


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 sagei. 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.

  • sagei. Aenictus wroughtonii var. sagei Forel, 1901a: 469 (w.) INDIA. Raised to species: Wilson, 1964a: 477. See also: Jaitrong, et al. 2010: 40.

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) - Syntypes: HW 0.51mm, HL 0.62mm, SL 0.54mm, Sl 106; HW 0.46mm, HL 0.60mm, SL 0.47 mm, Sl 102. HW of 7 other syntypes measured 0.46-0.53 mm. Close to wroughtoni, differing as follows: larger; with much shorter scapes; the petiolar node a little higher; a broad triangular area covering most of central occiput and vertex infuscate, contrasting with the yellow coloration of the remainder of head (wroughtoni is concolorous yellow). While sagei may in time prove to be a northern geographic variant of wroughtoni, I have considered the characters listed here adequate to justify provisional species rank for a form already bearing a name.

Jaitrong et al. (2010) - Worker lectotype and paralectotypes (n = 6): TL 3.1-3.2 mm; HL 0.63-0.65 mm; HW 0.50-0.53 mm: SL 0.50-0.53 mm: ML 1.0-1.1 mm; MTL 0.55-0.58 mm; PL 0.25 mm; CI 80-81; SI 100.

Head in full-face view subrectangular, distinctly longer than broad, with feebly convex sides and almost straight posterior margin; anterior portion slightly broader than posterior portion. Antennal scape short (shorter than head length: SI 100), not extending beyond the posterior margin of head; antennal segment II as long as III or less: II and III each clearly longer than each of IV-VII; VIII and IX combined as long as the last antennal segment (X). Frontal carina longer than in the other species of this group, extending posteriad beyond the posterior margin of antennal torulus. Clypeus short, with its anterior margin bearing 9-10 denticles. Mandible with the apical tooth large and curved, followed by 10-11 minute teeth on masticatory margin. Mesosoma elongate: in profile pronotum strongly convex dorsally; promesonotum sloping gradually to metanotal groove. Propodeum slightly lower than promesonotum; its dorsal outline almost straight propodeal junction rounded; declivity of propodeum flattened, laterally margined with a weak ridge. Petiole small, in profile rounded dorsally; subpetiolar process weakly developed, with its ventral outline nearly straight; its anteroventral corner obtusely angulate: postpetiole slightly smaller than petiole, with its node rounded and scarcely longer than broad.

Body extensively smooth and shiny. Anteriormost portion of pronotum minutely punctate; upper portion of mesopleuron with fine rugae.

Body with a few long standing hairs mixed with short decumbent hairs over the surface; length of the longest pronotal hair 0.20-0.25 mm. Head, mesosoma, waist and gaster deep yellow to pale brown; mandible pale yellow: antenna and legs extensively yellow.

Type Material

Jaitrong et al. (2010) - Six syntype workers (two pins, three on each pin) from Dharmsala. India (Musee d'Histoire Naturelle Genève, examined). One worker (top on a pin) is selected as the lectotype, the others as paralectotypes.

References