Aenictus fulvus

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

Aenictus fulvus is probably a Sundaland species. We found a colony in a rubber tree plantation in southern Thailand (type series). Elsewhere it has been collected mostly in lowland primary rainforests. The type series was found under a large rotting log during the wet season; no worker activity was seen around the log and no immatures were found in the bivouac. The colony was preying on ants from the genus Crematogaster. (Jaitrong and Yamane 2011)

Identification

A member of the laeviceps species group. Jaitrong and Yamane (2011) - A. fulvus is quite similar to Aenictus alticola and Aenictus luzoni in having a slender body with the surface almost smooth and shiny. Compared with these species, A. fulvus is much smaller (HW 0.53–0.65 mm in A. fulvus; 0.80– 0.85 mm in A. alticola; 0.78 mm in A. luzoni) and has a low subpetiolar process without anterior angle, and ventrally with a spiniform appendage directed downward and backward (in A. alticola and A. luzoni the subpetiolar process is low and anteriorly angulate with the ventral appendage not spiniform). The workers of three colonies from Ulu Gombak, Malay Peninsula (FI92MG-651, VW-04, and VW-03) are brighter than in the type series from Khao Nan National Park, southern Thailand. The size variation occurs among individuals from single colonies.

Keys including this Species

• Key to Aenictus laeviceps group species

Distribution

Malay Peninsula (S. Thailand and W. Malaysia), and Borneo (Sabah, Sarawak, Brunei, and E. Kalimantan)

Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo, Indonesia, Malaysia.
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 fulvus. 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 Online Catalogue of the Ants of the World.

• fulvus. Aenictus fulvus Jaitrong & Yamane, 2011: 34, figs. 28-30 (w.) THAILAND, WEST MALAYSIA, BORNEO (Brunei; East Malaysia: Sabah, Sarawak; Indonesia: Kalimantan).
  • Type-material: holotype worker, 137 paratype workers.
  • Type-locality: holotype Thailand: Nakhon Si Thammarat Prov., Khao Nan, 28.ix.2008, WJT08-S1101, rubber tree plantation (W. Jaitrong); paratypes with same data.
  • Type-depositories: TNHM (holotype); BMNH, FFKT, MBSM, MCZC, MHNG, SKYC, TNHM (paratypes).
  • Distribution: Brunei, Indonesia (Kalimantan), Malaysia (Peninsula, Sabah, Sarawak).

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 = 10): TL 2.95–3.10 mm; HL 0.63–0.75 mm; HW 0.53–0.65 mm; SL 0.48–0.60 mm; ML 0.90–1.05 mm; PL 0.23–0.25 mm; CI 84–87; SI 90–92.

holotype and paratypes - Head in full-face view subrectangular, much longer than broad, with sides rather parallel or feebly convex and posterior margin almost striaght; occipital carina complete. Antennal scape relatively short, not reaching posterolateral corner of head; antennal segments II–X each longer than broad; II almost as long as each of III–VII. Frontal carina very short, not extending beyond posterior margin of torulus. Anterior margin of clypeus feebly convex, bearing 4–6 denticles. Masticatory margin of mandible with a large apical tooth followed by a small subapical tooth, 3–4 denticles and a medium-sized basal tooth; basal margin bearing 2–3 small teeth. Mesosoma relatively slender; promesonotum in profile weakly convex dorsally and sloping gradually to metanotal groove; propodeum with dorsal outline almost straight; propodeal junction roundly angulate; declivity not margined dorsally and laterally. Petiole subsessile, almost as long as high; subpetiolar process well developed and hook-like, its apex directed downward and backward; postpetiole almost as long as petiole, only slightly higher than the latter.

Head including mandible and antennal scape entirely smooth and shiny. Mesosoma extensively smooth and shiny; area of metanotal groove striate; upper portion of metapleuron with about 10 irregular longitudinal rugae. Petiole and postpetiole entirely smooth and shiny. Legs entirely smooth and shiny.

Head and mesosoma dorsally with relatively sparse standing hairs mixed with sparse short hairs over the surface; longest pronotal hair 0.25–0.30 mm long. Body reddish-brown to yellowish-brown; dorsum of head darker. Typhlatta spot located anterior to occipital corner.

Type Material

Holotype worker from S. Thailand, Nakhon Si Thammarat Prov., Khao Nan, rubber tree plantation, 28 IX 2008, W. Jaitrong leg., WJT08-S1101 (Natural History Museum of the National Science Museum). One hundred and thirty-seven paratype workers, same data as holotype (Ant Museum, The Natural History Museum, Museum of Comparative Zoology, Musee d'Histoire Naturelle Genève, SKY Collection, THNHM, UMS).

Etymology

The specific name pertains to the pale body colour.

References

• Khachonpisitsak, S., Yamane, S., Sriwichai, P., Jaitrong, W. 2020. An updated checklist of the ants of Thailand (Hymenoptera, Formicidae). ZooKeys 998, 1–182 (doi:10.3897/zookeys.998.54902).
• Jaitrong, W. & Yamane, S. 2011. Synopsis of Aenictus species groups and revision of the A. currax and A. laeviceps groups in the eastern Oriental, Indo-Australian, and Australasian regions (Hymenoptera: Formicidae: Aenictinae). Zootaxa, 3128, 1–46. PDF
• Yamane, S., Tanaka, H.O., Hasimoto, Y., Ohashi, M., Meleng, P., Itioka, T. 2021. A list of ants from Lambir Hills National Park and its vicinity, with their biological information: Part II. Subfamilies Leptanillinae, Proceratiinae, Amblyoponinae, Ponerinae, Dorylinae, Dolichoderinae, Ectatomminae and Formicinae. Contributions from the Biological Laboratory, Kyoto University 31, 87–157.

References based on Global Ant Biodiversity Informatics

• Borowiec M. L. 2016. Generic revision of the ant subfamily Dorylinae (Hymenoptera, Formicidae). ZooKeys 608: 1–280.
• Jaitrong W. 2015. A revision of the Thai species of the ant genus Aenictus Shuckard, 1840 (Hymenoptera: Formicidae: Dorylinae). The Thailand Natural History Museum Journal 9(1): 1-94.
• Jaitrong W.; Yamane, S. 2011. Synopsis of Aenictus species groups and revision of the A. currax and A. laeviceps groups in the eastern Oriental, Indo-Australian, and Australasian regions (Hymenoptera: Formicidae: Aenictinae). Zootaxa 3128:1-46.