Aenictus jarujini

Aenictus jarujini
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Dorylinae
Genus:	Aenictus
Species:	A. jarujini
Binomial name
	Aenictus jarujini; Jaitrong & Yamane, 2010 Specimen Labels

This species is very rare and known only from the type locality (around 1000 m alt.). The specimens were collected from a bivouac under a stone in a disturbed area near a hill-evergreen forest during the dry season.

Identification

A member of the silvestrii species group. A. jarujini is very similar and closely related to Aenictus latifemoratus but the two are easily separated by the following characters: number of antennal segments (9 in A. jarujini; 8 in A. latifemoratus); shape of petiolar node (node subrectangular and relatively low, posteriorly margined with a rim in A. jarujini; node without a distinct rim in A. latifemoratus), condition of subpetiolar process (very low in A. jarujini; well developed and subtriangular in A. latifemoratus); sculpturing on head (strongly macropunctate in posterior dorsal half of head, other regions only weakly macropunctate in A. jarujini; strongly macropunctate or recticulate extensively on dorsum and sides of head in A. latifemoratus).

Keys including this Species

Key to Aenictus silvestrii group species

Distribution

Northern Thailand

Latitudinal Distribution Pattern

Latitudinal Range: 19.27849007° to 19.27849007°.


North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

Source: AntMaps

Distribution based on Regional Taxon Lists

Oriental Region: Thailand (type locality).

Distribution based on AntMaps

Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.

Biology

Explore Overview of Aenictus biology

Little is known about the biology of Aenictus jarujini. 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.

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Castes

Known only from the worker caste.

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

jarujini. Aenictus jarujini Jaitrong & Yamane, 2010: 329, figs. 1, 2 (w.) THAILAND.
- Type-material: holotype worker, 64 paratype workers.
- Type-locality: holotype Thailand: Mae Hong Son Prov., Haui Nam Dong Nat. Park, 7.iii.2008, WJT08-HND20 (W. Jaitrong); paratypes with same data.
- Type-depositories: TNHM (holotype); BMNH, MCZC, MZBJ, SKYC, TNHM (paratypes).
- Status as species: Khachonpisitsak, et al. 2020: 28.
- Distribution: Thailand.

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

Description

Worker

(n = 20): TL 3.4–3.8 mm; HL 0.83–0.93 mm; HW .70–0.80 mm; SL 0.40–0.47 mm; ML 1.13–1.25 mm; MTL 0.50–0.55 mm; PL 0.25– 0.30 mm; CI 82–89; SI 55–62.

Head in full-face view subrectangular, slightly longer than broad, with feebly convex sides and slightly concave posterior border; occipital margin concave bearing a narrow collar; area between frontal carina and parafrontal ridge depressed. Antenna 9-segmented; scape short, extending to the mid-length of head in full-face view; antennal segment II small, nearly as long as broad; III–V broader than long; VI–VIII nearly as long as broad; the terminal segment (IX) very large, almost as long as VII and VIII combined. Frontal carinae well developed, narrow, often with a longitudinal furrow (fused portion of the carinae) and extending half length of head; seen in profile its dorsal outline straight anteriorly and sloping gradually posteriad. Clypeus short and roundly produced anteriorly, lacking anterior teeth. Mandible with apical tooth large and curved, followed by 10–15 denticles of two sizes, the larger alternating with 2 or 3 smaller; basal margin of mandible lacking denticles. Mesosoma rather robust, seen from above wider anteriorly; posterior half almost parallel-sided; mesonotum laterally margined with ridges; in profile pronotum weakly convex dorsally and promesonotum sloping gradually to metanotal groove; propodeum slightly lower and weakly convex dorsally; mesopleuron not clearly demarcated from metapleuron; upper portion of mesometapleura extensively impressed. Propodeal junction acutely angulated; declivity of propodeum shallowly concave, encircled with a narrow rim. Petiole higher than broad, seen from above almost parallel-sided, anteriorly margined by a transverse carina, while posterior face encircled with a rim similar to that of propodeum; subpeiolar process low and subrectangular; postpetiole similar to petiole in shape and length, but without a well-demarcated posterior face, roundly convex above, impressed near posterior margin, anteroventrally pro-duced as a blunt angle directed downward and forward. Gaster elongate-elliptical, narrowed anteriorly and posteriorly.

Dorsum of head in posterior half with dense macro-punctures (almost reticulate) and micropunctures, and in anterior half with micropunctures and several longitudinal rugulae; sides of head with micropunctures, and sparse and shallow macropunctures. Mandible largely with dense minute punctures, but smooth apically and along masticatory margin. Upper face of antennal scape

basally with dense micropunctures and apically much smoother. Dorsal surface of mesosoma weakly and irregularly sculptured, with ill-defined micropunctures, and mat; lateral face of mesosoma densely micropunctate. Petiole dorsally with very superficial reticulum superimposed with dense micropunctures (a condition similar to posterodorsal part of head); postpetiole densely micropunctate. Gaster smooth and shining except for extreme basal portion. Femora and tibiae smooth and shining.

Body with relatively sparse standing hairs mixed with sparse short hairs over the surface; length of the longest pronotal hair approximately 0.20–0.25 mm. Head, mesosoma and waist pale brown; gaster and legs yellow; mandible blackish brown.

Type Material

Holotype. Worker from disturbed area, Haui Nam Dang National Park, Mae Hong Son Province, N. Thailand, 7 iii 2008, W. Jaitrong leg., colony WJT08HND20. Paratypes. 64 workers, same data as holotype. Type depository. Holotype and some paratypes are deposited in THNHM, and some paratypes in SKYC, BMHN, MCZC, and MZB.

Etymology

The specific name is dedicated to the late Dr Jarujin Nabhitabhata of the Thailand Natural History Museum, National Science Museum, who was the most excellent specialist in biodiversity sciences in Thailand and helped and inspired many young biologists.

References

References based on Global Ant Biodiversity Informatics

Borowiec M. L. 2016. Generic revision of the ant subfamily Dorylinae (Hymenoptera, Formicidae). ZooKeys 608: 1–280.
CSIRO Collection