Aenictus changmaianus Terayama et Kubota, 1993

Jaitrong, Weeyawat & Hashimoto, Yoshiaki, 2012, Revision of the Aenictus minutulus species group (Hymenoptera: Formicidae: Aenictinae) from Southeast Asia, Zootaxa 3426 (1), pp. 29-44 : 31-32

Aenictus changmaianus Terayama et Kubota, 1993

( Figs 1 A–E, 7)

Aenictus changmaianus Terayama et Kubota, 1993: 68 , figs 2–4.

Types. Holotype and three paratype workers from Thailand, Chang Mai Prov. [Chiang Mai Prov.], Doi Step [Doi Suthep N.P.], 1500 m, 18.VIII.1992, M. Terayama and S. Kubota leg. ( NIAST and NSMT; two paratypes examined).

Measurements. Paratypes (n = 2): TL 2.00– 2.05 mm; HL 0.48–0.50 mm; HW 0.39–0.40 mm; SL 0.28 mm; ML 0.63 mm; PL 0.14 mm; CI 78–84; SI 69–71.

Non-type workers (n = 6): TL 1.95–2.60 mm; HL 0.50–0.58 mm; HW 0.38–0.50 mm; SL 0.26–0.35 mm; ML 0.58–0.80 mm; PL 0.13–0.19 mm; CI 75–89; SI 68–72.

Description of worker (paratypes and non-types). Head in full-face view rectangular, clearly longer than broad, with almost parallel sides and shallowly concaved posterior margin. Antennal scape reaching midlength of head; antennal segment II longer than broad; III–IX each broader than long; terminal segment (X) distinctly longer than broad and 2.1 times as long as broad. Frontal carina very short, not extending beyond the level of posterior margin of torulus. Masticatory margin of mandible with a large apical tooth followed by a medium-sized subapical tooth, 1–4 denticles and a medium-sized basal tooth; basal margin with 2–3 small denticles. Mesosoma seen in profile almost flat or weakly convex dorsally; suture between mesopleuron and metapleuron present; metanotal groove indistinct; metapleural gland bulla large and transparent; distance between propodeal spiracle and metapleural gland bulla shorter than or almost as long as spiracular diameter ( Fig. 1 D). Propodeal junction obtusely angulated; declivity of propodeum with lateral carinae, but not demarcated basally by a transverse carina. Petiole excluding subpetiolar process almost as long as high, with its dorsal outline convex; subpetiolar process large, rectangular; anterior corner and posterior corner each acutely angulate. Postpetiole higher than long, slightly smaller than petiole and its dorsal outline convex. Femora and tibiae incrassate and widened.

Head including mandible and antennal scape smooth and shiny; promesonotum, dorsa of petiole and postpetiole smooth and shiny; mesopleuron densely reticulate, but shiny; metapleural gland bulla almost smooth and shiny; lateral faces of propodeum, petiole, and postpetiole weakly microreticulate. Legs entirely smooth and shiny.

Head and mesosoma dorsally with relatively dense standing hairs mixed with sparse short hairs over the surface; longest pronotal hair 0.05 mm long. Ground color yellow.

Non-type material examined. VIETNAM: Nghe An, Tuong Duong Dist., Sang Le Forest, 3.IV.2006, K. Eguchi leg., Eg06-VN-08 ( SKYC); same loc., 2.IV.2006, K. Eguchi leg., Eg06-VN-05 ( SKYC); S. Vietnam, Dong Nai, S. Cat Tien N.P., behind the Head Quarter, 21.X.2004, K. Eguchi leg., Eg04-VN-758 ( SKYC); same loc., 14.X.2004, K. Eguchi leg., Eg04-VN-630 ( SKYC). THAILAND: N. Thailand, Chiang Mai Prov., Campus of Chiang Mai University, 10.VI.2001, K. Eguchi leg., Eg01-TH-161 (AMK, SKYC, THNHM,); N. Thailand, Chiang Mai Prov., Mae Tang Dist., Mae Hair Tai, 1.IX.2000, W. Jaitrong leg., WJT00-MHT02 (AMK, SKYC, THNHM); N. Thailand, Chiang Mai Prov., Mae Tang Dist., Wad Pha Deang, 8.IX.2000, W. Jaitrong leg., WJT00-WPD01 ( SKYC, THNHM); same loc., 9.IX.2000, W. Jaitrong leg., WJT00-WPD02 ( SKYC, THNHM); NE. Thailand, Loei Prov., Phu Luang W.S. (ca. 700 m alt.), 10.IV.2008, Sk. Yamane leg., TH08-SKY-66 ( SKYC, THNHM); NE. Thailand, Nakhon Ratchasima Prov., Sakaerat ERS., 14.XII.2010, S. Hasin leg., TH10-SH-01 ( SKYC, THNHM); same loc., 10.VII.1999, Sk. Yamane leg., TH99-SKY-23 ( SKYC, THNHM); same loc., 4.III.2005, S. Hasin leg., WJT05- NE50 ( SKYC, THNHM); same loc., 18.X.2002, W. Jaitrong leg., WJT02-1 ( SKYC, THNHM). CAMBODIA: Kampong Cham Prov., Rubber plantation, 30.IV.2010, S. Hosoishi leg., Winkler extraction #1 ( THNHM).

Distribution. Vietnam (new record), Thailand and Cambodia (new record) ( Fig. 7 ).

Bionomics. No biological information is available for A. changmaianus . However, we found this species in highland seasonal forests (hill evergreen forest) and disturbed areas in northern Thailand (900–1500 m). In eastern Thailand and southern Vietnam it was collected from lowland seasonal forests (dry evergreen forest), secondary forests, and plantations (160–700 m), thus this species probably ranges from lowland to highland and inhabits both primary and disturbed forests.

Remarks. Aenictus changmaianus is very similar in general appearance to A. minutulus , and A. minimus . However, A. changmaianus is separated from A. minimus by the dentition on the basal margin of the mandible (see couplets 5 and 6 in the key) and antennal scape being relatively longer than in the latter (SI 67–72 in A. changmaianus ; SI 63–64 in A. minimus ). It is distinguished from A. minutulus by the large metapleural gland bulla (relatively small in A. minutulus ).

Figures

FIGURE 1. Aenictus changmaianus (A, B, C, paratype; D, E, non-type from Chiang Mai Province, N. Thailand). A, Head in full-face view; B, body in dorsal view; C, body in profile; D, propodeal junction, petiole and postpetiole in profile; E, mandible.

FIGURE 7. Distribution of the Aenictus minutulus group.