Aenictus thailandianus Terayama & Kubota, 1993

Jaitrong, Weeyawat & Yamane, Seiki, 2013, The Aenictus ceylonicus species group (Hymenoptera, Formicidae, Aenictinae) from Southeast Asia, Journal of Hymenoptera Research 31, pp. 165-233 : 207-208

Aenictus thailandianus Terayama & Kubota Fig. 17A-D

Aenictus thailandianus Terayama et Kubota, 1993: 71, figs 11-13.

Type material.

Holotype and 39 paratype workers (NAIST, SKYC) from N. Thailand, Chang Mai [Chiang Mai], Doi Step [Doi Suthep-Pui N.P.], ca. 1500 m alt. Six paratype workers (SKYC) were examined.

Non-type material examined.

VIETNAM: N. Vietnam, Bac Giang, Tay Yen Tu (150 m alt.), 22.V.2004, leg. K. Eguchi, Eg04-VN-072 (SKYC); M. Vietnam, Nghe An Prov., Que Phong Dist., Ban Xan (1012 m alt.), 19.IV.1999, leg. T.V. Bui (SKYC). THAILAND: Chiang Mai Prov., Muang Dist., 9.VI.2001, leg. W. Jaitrong, WJT 01-DST01 (SKYC, THNHM); same loc. (pine evergreen forest), 8.VI.2001, leg. S. Hasin (SKYC, THNHM); Chiang Mai Prov., Doi Ang Khang, 21.VIII.1998, leg. Sk. Yamane, TH98-SKY-30 (SKYC, THNHM); same loc., 17.VIII.2001, leg. W. Jaitrong, WJT01-AK10 (SKYC, THNHM).

Worker measurements

(paratypes, n = 6). TL 3.33-3.50 mm; HL 0.68-0.78 mm; HW 0.65-0.73 mm; SL 0.50-0.58 mm; ML 1.10-1.23 mm; PL 0.28-0.33 mm CI 93-96; SI 77-81.

Worker description

(paratypes). Head in full-face view slightly longer than broad, sides convex, posterior margin almost straight and occipital corner roundly angulate; occipital margin bearing a carina. Antennal scape relatively long, extending beyond 2/3 of head length but not reaching posterolateral corner of head. Frontal carina relatively long and distinct, extending beyond the level of posterior margin of torulus. Parafrontal ridge indistinct, slightly extending beyond the level of posterior margin of torulus. Anterior clypeal margin almost straight or feebly concave, its lateral portions forming blunt angle. Masticatory margin of mandible with a large acute apical tooth followed by a medium-sized subapical tooth, 8 denticles, and a medium-sized basal tooth; basal margin straight, lacking denticle. Maximum width of gap between anterior clypeal margin and mandibles about 1.5 times as broad as maximum width of mandible. Promesonotum strongly convex dorsally and sloping gradually to metanotal groove; metanotal groove indistinct or almost absent; mesopleuron relatively short and clearly demarcated from metapleuron by a deep groove; mesonotum demarcated from mesopleuron by a conspicuous ridge; metapleural gland bulla relatively large, its maximum diameter about 3 times as long as distance between propodeal spiracle and metapleural gland bulla. Propodeum in profile with weakly convex dorsal outline; propodeal junction angulated, overhanging the declivitous face of propodeum; the declivity narrowly and shallowly concave, encircled with a thin rim. Petiole almost as long as high, its node with dorsal outline elevated posteriorly; subpetiolar process low, with forward-directed lobe whose ventral margin is straight or feebly concave. Postpetiole slightly shorter than petiole, with its dorsal outline convex.

Head and gaster entirely smooth and shiny. Mandible very finely striate. Antennal scape entirely punctate. Mesosoma, petiole, and postpetiole strongly reticulate. Lateral face of pronotum partly smooth or superficially reticulate; mesopleuron and lateral face of propodeum with relatively irregular longitudinal rugae. Legs weakly microreticulate except for smooth coxae.

Head and mesosoma dorsally with relatively dense standing hairs; longest pronotal hair 0.30-0.33 mm long. Antennal scape, mesosoma, petiole and postpetiole reddish brown; head, gaster and legs yellowish brown.

Distribution.

N. Vietnam and N. Thailand ( Fig. 24B ).

Bionomics.

Nothing is mentioned by Terayama and Kubota (1993) about the bionomics of Aenictus thailandianus . However, judging from the type series and non-type specimens examined this species mainly inhabits highlands (1000-1500 m alt.) in both primary and secondary forests.

Remarks.

Aenictus thailandianus is most similar to Aenictus cylindripetiolus in having the mandible with more than 4 teeth and entirely sculptured promesonotum. However, it can be separated from the latter by the following characteristics: Pronotum entirely punctate (reticulate in the latter); petiole almost as long as postpetiole, with high node (distinctly longer than high in the latter); femora superficially sculptured (punctate, shagreened or partly reticulate) (entirely smooth and shiny except basalmost portion micropunctate in the latter); body larger (TL 3.30-3.50 mm, HW 0.65-0.73 mm in the former; TL 2.90-3.15 mm, HW 0.60-0.65 mm in the latter).

Figures

Figure 17. Aenictus thailandianus (specimens from the type locality). A Head in full-face view B mandible C body in dorsal view D body in profile.

Figure 24. Distribution of Aenictus ceylonicus group. A Aenictus formosensis, Aenictus fuchuanensis, Aenictus lifuiae B Aenictus brevipodus, Aenictus concavus, Aenictus thailandianus, Aenictus wiwatwitayai.