Aenictus

Jaitrong, Weeyawat & Hashimoto, Yoshiaki, 2012, Revision of the Aenictus minutulus species group (Hymenoptera: Formicidae: Aenictinae) from Southeast Asia, Zootaxa 3426 (1), pp. 29-44 : 40-42

Aenictus sp. 56 of WJT

( Figs 2 A–F, 7)

Measurements. workers (n = 10): TL 1.80–2.10 mm; HL 0.45–0.53 mm; HW 0.38–0.44 mm; SL 0.25–0.33 mm; ML 0.60–0.71 mm; PL 0.15–0.18 mm; CI 83; SI 67–74.

Description of worker. Head in full-face view clearly longer than broad, with convex sides and weakly concave posterior margin; occipital margin bearing a carina. Antennal scape reaching midlength of head; antennal segments II–X each slightly longer than broad; II slenderer than III–VI; terminal segment 2.5 times as long as broad and slightly longer than VII+VIII+IX. Frontal carina very short, posteriorly fused to form a single carina, 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, 3–4 denticles, and a medium-sized basal tooth; basal margin with 5–6 small denticles. Promesonotum in profile convex dorsally and sloping gradually to metanotal groove; metanotal groove indistinct; metapleural gland bulla relatively small; distance between propodeal spiracle and metapleural gland bulla clearly longer than spiracular diameter ( Fig. 2 E). Propodeum in profile lower than promesonotum with straight dorsal outline; propodeal junction right-angled; declivity of propodeum shallowly concave, encircled with a thin rim. Petiole slightly longer than high, with its dorsal outline convex; subpetiolar process rather developed, with sharply pointed lamellate appendage directed downward. Postpetiole smaller than petiole, its dorsal outline convex.

Head including mandible and antennal scape smooth and shiny; basal portion of scape finely micropunctate. Entire pronotum smooth and shiny except for its anteriormost portion punctate; dorsum of propodeum partly smooth and shiny; mesothorax, metapleuron, and lateral face of propodeum microreticulate; area in front of propodeal junction punctate; petiole reticulate except dorsal face smooth and shiny; postpetiole entirely smooth and shiny. 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 0.11–0.12 mm long. Body yellowish-brown; gaster and legs yellow. Typhlatta spot absent.

Material examined. MALAYSIA: E. Malaysia, Borneo, Sabah, Tawau Hills N.P., 7.VII.1996, K. Eguchi leg., Eg96-BOR-73 ( SKYC, THNHM); E. Malaysia, Borneo, Sabah, Yoshina Ranau, logging area, 30.VI.1998, K. Eguchi leg., Eg98-BOR-853 ( SKYC, THNHM). INDONESIA: W. Java, Bogor, Kebun Raya (Bogor Botanical Garden), 11–31.I.1992, F. Ito leg., FI92-337 ( SKYC, THNHM).

Distribution. Borneo (Sabah) and Java ( Fig. 7 ).

Bionomics. One colony was collected from Bogor Botanical Garden (lowland). On Borneo one colony was found in a lowland rainforest and another from a logging area. Thus, this species is probably inhabits lowland primary and disturbed forests.

Remarks. Aenictus sp.56 of WJT is easily distinguished from the other members of the group as follows: propodeum in profile with straight dorsal outline, lower than promesonotum; propodeal junction right-angled; declivity of propodeum shallowly concave, encircled with a thin rim.

Figures

FIGURE 2. Aenictus sp. 56 of WJT (specimen from Borneo, FI 92 - 337). A, Head in full-face view; B, body in dorsal view; C, body in profile; D, declivity of propodeum, obliquely posterior view; E, propodeal junction, petiole and postpetiole in profile; F, mandible.

FIGURE 7. Distribution of the Aenictus minutulus group.