Aenictus pilosus

Aenictus pilosus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Dorylinae
Genus:	Aenictus
Species:	A. pilosus
Binomial name
Aenictus pilosus Jaitrong & Yamane, 2013

The type locality is located in the hinterland (1400m alt.).

Identification

A member of the ceylonicus group. Aenictus pilosus is most similar in general appearance to Aenictus wilaiae.

Keys including this Species

• Key to southeastern Asian Aenictus ceylonicus group species

Distribution

Philippines (Luzon and Mindanao)

Distribution based on Regional Taxon Lists

Indo-Australian Region: Philippines (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 pilosus. 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.

• pilosus. Aenictus pilosus Jaitrong & Yamane, 2013: 205, fig. 15A-C (w.) PHILIPPINES (Luzon).
  • Type-material: holotype worker, 17 paratype workers.
  • Type-locality: holotype Philippines: Luzon, Mountain Prov., Sagada, Bokong Waterfall, 1400 m., 19.ii.1999 (A. Schulz); paratypes with same data.
  • Type-depository: NHMW.
  • Distribution: Philippines (Luzon, Mindanao).

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 paratypes, n = 6). TL 2.70–2.80 mm; HL 0.60–0.63 mm; HW 0.50–0.53 mm; SL 0.48–0.50 mm; ML 0.93–0.95 mm; PL 0.24–0.25 mm; CI 83–88; SI 90–95.

Head in full-face view subrectangular, clearly longer than broad, sides weakly convex, and posterior margin almost straight or feebly convex. Antennal scape reaching 2/3 of head length. Frontal carinae fused at the level of antennal base to form a single carina, slightly extending beyond the level of posterior margin of torulus. Parafrontal ridge almost absent. Anterior clypeal margin weakly concave, lacking denticles and concealed by curved anterior extension of frontal carina. Masticatory margin of mandible with large acute apical tooth followed by a medium-sized subapical tooth, 2-3 denticles, and a medium-sized basal tooth; basal margin almost straight. Maximum width of gap between anterior clypeal margin and mandibles about 2.6 times as broad as maximum width of mandible. Promesonotum strongly convex dorsally and sloping gradually to metanotal groove; metanotal groove indistinct; mesopleuron not clearly demarcated from metapleuron. Propodeum in profile relatively long with almost straight dorsal outline; propodeal junction angulated, nearly right-angled; declivity of propodeum shallowly concave, and encircled with a rim; metapleural gland bulla relatively large, its maximum diameter about 2.5 times as long as distance between propodeal spiracle and metapleural gland bulla. Petiole slightly longer than high, elevated posteriorly; subpetiolar process generally very low, with its anteroventral corner acutely angulate, and ventral margin feebly concave. Postpetiole slightly smaller than petiole, with its dorsal outline convex.

Head and gaster smooth and shiny; basal half of antennal scape densely microreticulate but apical half smooth and shiny; mandible finely striate. Promesonotum smooth and shiny except for anteriormost portion punctate; mesopleuron with slightly irregular rugae; metapleuron, and propodeum wrinkled and reticulate. Petiole entirely reticulate; postpetiole superficially reticulate and shiny. Basal 1/3 of femora sculptured, apical 2/3 (swollen area) smooth and shiny; tibiae microreticulate, partly smooth and shiny.

Head and mesosoma dorsally with relatively dense standing hairs; longest pronotal hair 0.33–0.35 mm long; legs with dense long decumbent hairs. Head reddish brown; antenna, mandible, mesosoma, petiole and postpetiole dark reddish brown; gaster and legs yellowish brown.

Type Material

Holotype. PHILIPPINES: Worker from Philippines, Luzon, Mountain Prov., Sagada, Bokong waterfall, 1400 m alt., 19.II.1999, leg. A. Schulz, (NHMW). Paratypes. Seventeen workers, same data as holotype (NHMW).

Etymology

The specific epithet “pilosus” is a Latin word meaning pilose. This refers to long decumbent hairs on the legs.

References

• Cantone S. 2018. Winged Ants, The queen. Dichotomous key to genera of winged female ants in the World. The Wings of Ants: morphological and systematic relationships (self-published).
• Dhadwal, T., Bharti, H. 2023. Aenictus dirangensis sp. nov. (Hymenoptera: Formicidae), a new species of Aenictus ceylonicus group from India. Journal of the Entomological Research Society 25(2): 387-403 (doi:10.51963/jers.v25i2.2367).
• Jaitrong, W. & Yamane, S. 2013. The Aenictus ceylonicus species group (Hymenoptera, Formicidae, Aenictinae) from Southeast Asia. Journal of Hymenoptera Research 31:165-233.

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., and S. Yamane. 2013. The Aenictus ceylonicus species group (Hymenoptera, Formicidae, Aenictinae) from Southeast Asia. Journal of Hymenoptera Research 31: 165-233.