Aenictus laeviceps

Widespread and dominant in rainforests of Southeast Asia (Gotwald 1995).

Identification
A member of the laeviceps species group. A. laeviceps is closely related to Aenictus breviceps, Aenictus sonchaengi, and Aenictus rotundicollis in having only 2 standing hairs on the vertex of the head. It has a more weakly convex promesonotum in profile than the last two (promesonotum strongly convex in A. sonchaengi and A. rotundicollis). It is also separated from them by the absence of standing hairs on the pronotum (more than 4 hairs present in A. sonchaengi; 2–4 hairs in A. rotundicollis). Another character separating A. laeviceps from A. rotundicollis is the relative length of the petiole, which is longer than high in the former but shorter than high in the latter. For the differences between A. laeviceps and A. breviceps, see A. breviceps. (Jaitrong and Yamane 2011)

Distribution
E. Thailand, Malay Peninsula (S. Thailand and W. Malaysia), Sumatra, Borneo (Sabah, Sarawak, and Brunei), and Philippines (Jaitrong and Yamane 2011).

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia, Philippines, Singapore. Oriental Region: Bangladesh, India, Myanmar, Thailand, Vietnam. Palaearctic Region: China.

Biology
Jaitrong and Yamane (2011) - A. laeviceps is widespread and dominant in rainforests of Southeast Asia (Gotwald 1995). We found it foraging in lowland seasonal forests (dry evergreen forest) in eastern Thailand. Elsewhere it was collected from tropical rainforests generally at less than 1,000 m alt. A single colony may contain as many as 60,000 to 110,000 workers (Schneirla & Reyes 1966).



This species forages mainly on the ground (Hirosawa et al. 2000) but sometimes climbs up trees. We observed this species preying on other ants such as Anoplolepis gracilipes (Philippines), Camponotus (Sumatra, Thailand), Euprenolepis (Thailand), Polyrhachis (Borneo), Pseudolasius (Borneo), and also on grasshoppers (Thailand). Wilson (1964) mentioned that A. laeviceps preyed on other ant species such as Camponotus (Tanaemyrmex) carin, Diacamma sp., Echinopla sp., Hypoclinea sp. [Dolichoderus sp.], Myrmicaria sp., Pristomyrmex sp., Paratrechina longicornis, Polyrhachis (Polyrhachis) bellicosa, Polyrhachis (Myrmhopla) sp., and Polyrhachis (Myrma) sp., Ponera sp., Vollenhovia sp., and also on the social wasp, Ropalidia flavopicta''. Chapman (1964) found this species feeding on myriapods, termites, small staphylinid beetles, while Rościszewski and Maschwitz (1994) mentioned that ants of the genera Crematogaster, Paratrechina, Pheidole, Polyrhachis, and Prenolepis were the prey of A. laeviceps. Hirosawa et al. (2000) reported that dominant prey genera were Camponotus (48.2%), Pseudolasius (20.8%) and Polyrhachis (15.2%) in the vicinity of Poring, Sabah, Borneo at altitudes of 600–800 m.

Wheeler (1930) - Described from a single specimen taken by Dr. Chapman on May 23, 1923, from a colony that had been making raids for two days on other ants and miscellaneous insects near his camp in the mountains back of Dumaguete. This colony finally bivouacked under an overhanging rock and when a fire was built very near it and it again began to migrate, the female, many workers, much brood and a number of amictophiles were captured. The contracted and strongly overlapping segments of the gaster of the female indicate that she was not in an actively egglaying condition, and the many hundreds of workers and fullgrown larvae in the colony indicate that she must be either an old and exhausted mother or a young substitute queen that had not yet entered on her period of great fecundity. Her fresh and unabraded appearance would seem to argue in favor of the latter supposition.

Nomenclature

 *  laeviceps. Typhlatta laeviceps Smith, F. 1857a: 79 (w.) BORNEO. Wheeler, W.M. 1930g: 200 (q.); Wheeler, G.C. & Wheeler, J. 1984: 265 (l.). Combination in Aenictus: Forel, 1890b: ciii. Senior synonym of  smythiesii, sundaica: Wilson, 1964a: 467. See also: Jaitrong & Yamane, 2011: 36.
 * smythiesii. Aenictus laeviceps var. smythiesii Forel, 1901a: 465 (diagnosis in key) (w.) INDIA. Junior synonym of laeviceps: Wilson, 1964a: 467.
 * sundaica. Eciton (Aenictus) fergusoni var. sundaica Karavaiev, 1927e: 7 (w.) INDONESIA (Java). [Unresolved junior secondary homonym of sundaicus Forel, above.] Junior synonym of laeviceps: Wilson, 1964a: 467.

Jaitrong and Yamane (2011) - The specimens collected from southern Thailand, Sumatra, and Borneo (Sarawak, Sabah, and Brunei) agree well with the lectotype from Sarawak, except in 2 colonies (SU07-SKY-199 and SU08-Kei282) from Sumatra in which the workers have 1–2 standing hairs on the pronotum. In the single colony (PH98-SKY-26) from the Philippines the propodeal junction of the worker is rounder than in the lectotype, and also the body size is slightly smaller. Zhou (2001) cited Guangxi, southern China as a locality of A. laeviceps, but according to the distribution range of this species the identification is doubtful.

Worker
Jaitrong and Yamane (2011) - Measurements. A worker lectotype: TL 4.15 mm; HL 0.93 mm; HW 0.80 mm; SL 0.83 mm; ML 1.35 mm; PL 0.33 mm; CI 86; SI 103. Non-type workers (n = 9): TL 3.90–4.15 mm; HL 0.88–0.92 mm; HW 0.70–0.82 mm; SL 0.73–0.87 mm; ML 1.30–1.40 mm; PL 0.28–0.33 mm; CI 86–92; SI 103–113.

Lectotype and non-type material from Borneo - Head in full-face view clearly longer than broad, with sides and posterior margin strongly convex; occipital margin bearing a carina. Antenna relatively long, scape almost reaching the posterolateral corner of head; antennal segments II–X each longer than broad. Frontal carina short, slightly extending beyond the level of the posterior margin of torulus. Anterior margin of clypeus convex, bearing 6–8 denticles. Masticatory margin of mandible with a large apical tooth followed by a medium-sized subapical tooth, 4–5 denticles, and a medium-sized basal tooth; basal margin lacking denticles. Promesonotum in profile convex dorsally; propodeum much lower than promesonotum, and in profile its dorsal outline almost straight; propodeal junction right-angled; declivity of propodeum weakly concave, encircled with an indistinct rim. Mesopleuron demarcated from metapleuron by a shallow groove. Petiole longer than high, in profile its dorsal outline almost straight or weakly convex in posterior portion; subpetiolar process well developed, its lobe surmounted by a thin, acute flange that is directed downward and backward; postpetiole slightly shorter than petiole, in dorsal view scarcely longer than broad.

Head entirely smooth and shiny. Antennal scape microrecticulate and subopaque, slightly shiny. Mandible finely microsculptured and feebly shiny. Pronotum smooth and shiny, its anteriormost portion punctate; mesothorax, metapleuron and propodeum with dense punctures; upper portion of mesopleuron and metapleuron with 15-20 irregular longitudinal rugulae; propodeum with about 40 densely packed, nearly straight, fine rugulae; interrugal spaces irregulary microrecticulate and opaque to feebly shiny. Petiole with dense punctures; postpetiole entirely smooth and shiny. Femora extensively but superficially reticulate and shiny; tibiae very finely reticulate.

Head with a pair of standing hairs on vertex; mesosoma devoid of pilosity. Entire body dark reddish brown. Typhlatta spot located anterior to occipital corner.

Type Material
Typhlatta laeviceps

Two worker syntypes in. Labelled “SAR. 38.”

Jaitrong and Yamane (2011) - Typhlatta laeviceps: Three syntype workers from Borneo, Sarawak ( and, examined). A syntype in BMNH is selected as the lectotype, others as paralectotypes.

Eciton (Aenictus) fergusoni var. sundaica. Type locality: Prinsen I. [Panaitan I.], Sunda Strait, nr Java.