Aenictus lifuiae, Jaitrong & Yamane, 2013

Jaitrong, Weeyawat & Yamane, Seiki, 2013, The Aenictus ceylonicus species group (Hymenoptera, Formicidae, Aenictinae) from Southeast Asia, Journal of Hymenoptera Research 31, pp. 165-233 : 195-197

Aenictus lifuiae Terayama Fig. 11A-D

Aenictus lifuiae Terayama, 1984: 13, figs 1-13; Bolton, 1995: 60; Terayama, 2009: 124 (in key).

Types.

Holotype (NAIST), 152 paratype workers (NAIST, TARI) and 1 paratype male (NAIST) from Taiwan, Kaoshiung Hsien, Taoyuan Xiang, Meishan Cun (ca. 800 m alt.). Holotype and nine paratype workers were examined.

Non-type material examined.

JAPAN: S. Japan, C. Ryukyu, Okinawa-jima, Kunigami, 21.X.2006, leg. H. Ohnishi, Ohnishi-I-3 (SKYC, THNHM); S. Japan, S. Ryukyus, Taketomi-cho, Urauchi (Iriomote-jima), 10.X.2008, leg. M. Maruyama & T. Komatsu (SKYC, THNHM).

Worker measurements

(holotype and paratypes, n = 10). TL 2.55-2.80 mm; HL 0.53-0.58 mm; HW 0.48-0.53 mm; SL 0.39-0.45 mm; ML 0.75-0.88 mm; PL 0.18-0.23 mm CI 90-91; SI 82-86.

Non-type workers (larger): TL 2.80-2.85 mm; HL 0.55-0.58 mm; HW 0.50-0.53 mm; SL 0.40-0.41 mm; ML 0.83-0.88 mm; PL 0.20-0.23 mm CI 91-95; SI 76-80.

Non-type workers (smaller): TL 2.10-2.20 mm; HL 0.48-0.50 mm; HW 0.40-0.43 mm; SL 0.23-0.25 mm; ML 0.63-0.68 mm; PL 0.15-0.18 mm CI 84-85; SI 56-59.

Worker description

(holotype and paratypes). Head in full-face view subrectangular, distinctly longer than broad, with sides slightly convex and posterior margin almost straight. Antennal scape extending beyond midlength of head, but not reaching 2/3 of head length; antennal segment II almost as long as III and each longer than broad; IV-VIII each slightly broader than long; terminal segment about 2 times as long as broad. Frontal carina short, slightly extending beyond the level of posterior margin of torulus. Masticatory margin of mandible with a large apical tooth, followed by 6 teeth of two sizes, a larger alternating with a smaller; basal margin lacking denticles. In smaller workers maximum width of gap between anterior clypeal margin and mandibles about 0.9-1.0 times as broad as maximum width of mandible (larger workers almost lacking the gap). Promesonotum in profile strongly convex dorsally and sloping gradually to metanotal groove; metanotal groove rather distinct but shallow; mesopleuron clearly demarcated from metapleuron by a shallow groove; metapleural gland bulla relatively large and transparent, its maximum diameter about 3.0-3.5 times as long as distance between propodeal spiracle and metapleural gland bulla. Propodeum in profile with weakly convex to almost straight dorsal outline; propodeal junction angulated; declivity of propodeum narrowly and shallowly concave, encircled with a distinct rim. Petiole excluding subpetiolar process almost as long as high, with its dorsal outline convex; subpetiolar process weakly developed, with its ventral outline convex. Postpetiole clearly shorter than petiole, its dorsal outline convex.

Head and gaster entirely smooth and shiny. Mandible very finely striate. Antennal scape entirely superficially microreticulate, but shiny. Promesonotum entirely smooth and shiny except for reticulate anteriormost portion; mesopleuron, metapleuron, lateral face of propodeum reticulate; dorsal face of propodeum punctate, somewhat shiny; petiole with reticulate lateral face and smooth and shiny dorsal face; postpetiole same as petiole. Legs smooth and shiny.

Head and mesosoma dorsally with relatively dense standing hairs; longest pronotal hair 0.13-0.15 mm long. Head, petiole, postpetiole, gaster, and legs yellowish brown; mesosoma reddish brown.

Distribution.

Japan and Taiwan ( Fig. 24A ).

Bionomics.

Terayama (1984) reported that the material from Meishan Cun was taken "at hard clay soil of the road cutting about 50 cm above ground level". When another person saw it at 5 p.m., the colony was prepared for the nuptial flight. One male was in the nest entrance, and about 40 workers were seen coming out of the nest, gathering around the entrance in a circle.

Remarks.

Jaitrong and Yamane (2011) included Aenictus lifuiae in the Aenictus minutulus group (referred to as the Aenictus piercei group). However, after a careful examination of the smaller specimens of Aenictus lifuiae collected from Iriomote-jima and Okinawa-jima, southern Japan, we found that their mandible is almost linear, the anterior clypeal margin is straight or weakly concave, and that a gap occurs between the mandibles and anterior clypeal margin. These characteristics are used to separate the Aenictus ceylonicus group from the other groups of the genus Aenictus , and also these specimens possess other conditions shared with the Aenictus ceylonicus group. We finally decided to remove Aenictus lifuiae from the Aenictus minutulus group and transfer it to the Aenictus ceylonicus group.

Aenictus lifuiae , though variable in size and associated morphological characters, is easily distinguished from the other members of the group as follows: masticatory margin of mandible with large acute apical tooth followed by a series of 6-7 denticles of two sizes, the larger alternating with 1-2 smaller (almost same size as in the other members of the group); a gap between anterior clypeal margin and mandibles rather small or indistinct, maximum width shorter than 1 time as wide as maximum width of mandible (large and distinct in the others).

Three specimens collected from Okinawa-jima, Japan are slightly larger than the type series from Taiwan (HW 0.48-0.53 mm in the type series; 0.55-0.58 mm in Okinawan specimens). The Japanese Ant Database Group (2003) recorded two Aenictus species, i.e., Aenictus lifuiae and Aenictus ceylonicus from the Ryukyus, Japan. The pictures for Aenictus lifuiae should be of the true Aenictus lifuiae , although those for Aenictus ceylonicus are most probably of Aenictus formosensis . Up to now we did not see any specimen of the latter from Japan.

Figures

Figure 11. Aenictus lifuiae (paratype). A Head in full-face view B body in dorsal view C mandibles 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.