Aenictus cornutus Forel

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 : 11-12

Aenictus cornutus Forel

( Figs. 1–2 )

Aenictus cornutus Forel, 1900: 75 ; Wilson, 1964: 457, figs. 21–22; Bolton, 1995: 59.

Types. Four syntype workers (two on each of the two pins) from Borneo, Sarawak (MHNG, examined). One worker among them (bottom on a pin) is selected as the lectotype, the others as paralectotypes.

Measurements. Worker lectotype and paralectotypes (n = 4): TL 4.00– 4.45 mm; HL 0.83–0.88 mm; HW 0.73–0.78 mm; SL 0.80–0.88 mm; ML 1.48–1.55 mm; PL 0.35–0.38 mm; CI 86–89; SI 107–114.

Redescription of worker (lectotype and paralectotypes). Head in full-face view clearly longer than broad, with sides slightly convex and posterior margin sinuate; occipital margin bearing a narrow collar. Antenna relatively thick; scape not reaching posterolateral corner of head; antennal segments II–VI slightly longer than broad, of approximately same length; VII–IX thicker and slightly longer; X slightly longer than VIII+IX. Frontal carina short, slightly extending beyond the level of posterior margin of torulus and well developed anteriorlly. Parafrontal ridge short and bluntly pointed at apex. Masticatory margin of mandible with a large apical tooth followed by a medium-sized subapical tooth and 5–6 denticles; basal margin of mandible lacking denticles.

Mesosoma slender; pronotum anteriorly armed with large bilateral horn-like protuberances, a unique character within the species group. Propodeum in profile with weakly convex dorsal outline; propodeal junction angular; declivity of propodeum shallowly concave, and encircled with a thin rim. Petiole distinctly longer than high, with its dorsal outline elevated posteriorlly; subpetiolar process low, with its anteroventral corner angulate, and ventral margin almost straight, sometimes with lamellate lower portion. Postpetiole distinctly longer than high, with its dorsal outline convex.

Head entirely smooth and shiny. Mandible very finely striate except for masticatory and outer zones. Antennal scape punctate. Pronotum smooth and shiny except for the anteriormost portion and pronotal horns which are punctate; mesothorax, metapleuron, and propodeum with dense punctures and bearing several longitudinal rugulae. Petiole and postpetiole densely punctate as are metathorax and propodeum. Legs densely punctate.

Head and mesosoma dorsally with relatively sparse long standing hairs mixed with dense short hairs; longest pronotal hair 0.35 mm long. Entire body dark reddish-brown. Typhlatta spot located at the occipital corner.

Non-type material examined. MALAYSIA: W. Malaysia, Ulu Gombak, VII–IX 1992, F. Ito leg., MG445 ( SKYC); Sabah, Kinabalu, Poring, 8 V 1997, H. Hirosawa leg. ( SKYC); Sabah, same loc., 23 XI 1996, K. Eguchi leg., Eg96-BOR-295 ( SKYC, THNHM); Sabah, Gunong Rara, Tawau, 19 II 1997, K. Eguchi leg., Eg97-BOR-540 ( SKYC, THNHM); Sarawak, Mulu, 13 XII 1993, Sk. Yamane leg. ( SKYC, THNHM); Sarawak, Ng. Mabau, 2 XI 1993, Het leg. ( SKYC); Sarawak, Miri, T. Matsumoto leg., GAAP 5HC23. INDONESIA: W. Sumatra, Lubuk Gadang, 21–23 VIII 1985, Sk. Yamane leg. ( SKYC, THNHM).

Distribution. Malay Peninsula (W. Malaysia), Sumatra, and Borneo (Sabah and Sarawak) ( Fig. 23 ).

Bionomics. Aenictus cornutus is very probably restricted to Sundaland. All colonies of this species were collected from lowland rainforests. RoŠciszewski and Maschwitz (1994) reported that in the Pasoh Forest Reserve, Malaysia, A. cornutus foraged on the ground and fed on ants of the genera Polyrhachis and Technomyrmex .

Remarks. This species is easily distinguished from the other members of the group as follows: pronotum armed with large bilateral horn-like protuberances; antennal scape, legs and postpetiole distinctly punctate.

Figures

FIGURES 1 – 4. Workers of Aenictus currax group. 1, 2, A. cornutus, lectotype; 3, 4, A. gracilis, lectotype. 1, 3, Head in fullface view; 2, 4, habitus in profile.

FIGURES 23 – 25. Distribution of Aenictus currax group. 23, A. cornutus and A. parahuonicus sp. nov.; 24, A. gracilis; 25, A. glabrinotum sp. nov., A. pfeifferi, and A. wayani sp. nov.