Aenictus pachycerus

Jaitrong, Weeyawat & Yamane, Seiki, 2011, Synopsis of Aenictus species groups and revision of the A. curra x and A. laeviceps groups in the eastern Oriental, Indo-Australian, and Australasian regions (Hymenoptera: Formicidae: Aenictinae), Zootaxa 3128, pp. 1-46 : 8-9

Aenictus pachycerus group

Diagnosis. Antenna long, consisting of 10 segments; scape long, reaching or extending beyond posterolateral corner of head. Anterior clypeal margin roundly convex in the middle, lacking denticles. Mandible triangular, with very dense punctures; its masticatory margin with a large and sharp apical tooth followed by 4–12 small inconspicuous denticles, which gradually reduce in size toward basal angle of mandible. Frontal carinae fused at the level of antennal base to form a single carina, and extending less than half length of head, and well developed anteriorly and poorly developed posteriorly; parafrontal ridge present, reaching less than half length of head; seen in profile its anteriormost part well developed and raised as a subtriangular process. Occipital margin forming a collar or carina. Promesonotum distinctly convex or very weakly convex dorsally and sloping gradually to propodeum; propodeal junction angular; declivity of propodeum concave, encircled with a rim. Subpetiolar process weakly developed.

Head entirely sculptured or smooth and shiny. Petiole and postpetiole densely punctate in at least Southeast Asian species. First gastral segment entirely smooth and shiny, or rarely superficially shagreened, except the base of the tergite and sternite that has small, dense punctures. Body black, dark or reddish brown to light or yellowish brown; typhlatta spot absent.

Remarks. The A. pachycerus group consists of relatively large species in terms of body size (TL 3.20–4.65 mm). Wilson (1964) pointed out that this group is closely related to the A. philippinensis group, but can be distinguished from the latter by the mesonotum not visibly demarcated from the mesopleuron, and the metanotal groove almost absent or indistinct (mesopleuron clearly demarcated from metapleuron by a deep groove and from promesonotum by a distinct carina and metanotal groove relatively deep and distinct in the latter). This species group is also related to the A. hottai group in having developed frontal carina and parafrontal ridge. See under the A. hottai group.

Distribution. India, Sri Lanka, S. China, Vietnam, Thailand, Malay Peninsula (S. Thailand and W. Malaysia), Sumatra, Borneo (Sabah, Sarawak, Brunei, and E. Kalimantan), Philippines, New Guinea ( Papua), and Australia (Queensland).

Currently valid names for the Oriental, Indo-Australian, and Australasian forms. A. aitkenii Forel, 1901 ; A. aratus Forel, 1900 ; A. bobaiensis Zhou et Chen, 1999 ; A. carolianus Zettel et Sorger, 2010 ; A. chapmani Wilson, 1964 ; A. dentatus Forel, 1911 ; A. levior (Karavaiev, 1926) ; A. nesiotis Wheeler et Chapman, 1930 ; A. pachycerus (Fr. Smith, 1858) ; A. philiporum Wilson, 1964 ; A. powersi Wheeler et Chapman, 1930 ; A. prolixus Shattuck, 2008 ; A. puensis Forel, 1901 ; A. reyesi Chapman, 1963 .