Aenictus yamanei

Aenictus yamanei, together with its close relative Aenictus hottai, are the only members of the A. hottai species group. Both are probably restricted to Sundaland (south-east Asia) and inhabit lowland primary rainforests.

Identification
A member of the hottai species group.

Wiwatwitaya and Jaitrong (2011) - For discrimination of this species from Aenictus hottai, see below and under A. hottai. The workers of two colonies collected from West Malaysia (MG103 and FI92MT-10) are slightly smaller and brighter than those of the type series.


 * Larger species (HW 0.93-1.00 mm; ML 1.63-1.75 mm); head relatively shorter (CI 88-91) . . . . . Aenictus hottai


 * Smaller species (HW 0.63-0.70 mm; ML 1.22-1.27 mm); head relatively longer (CI 79-85) . . . . . Aenictus yamanei

Key to Aenictus species groups

Distribution
Malay Peninsula (Malaysia) and Borneo (Sarawak).

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia. Oriental Region: Thailand.

Biology
Wiwatwitaya and Jaitrong (2011) - A. yamanei is sympatric with A. hottai in at least Ulu Gombak, Malay Peninsula. All colonies of A. yamanei were collected from the forest floor in the lowland primary forest. So far we have no information about its prey.

Castes
Known only from the worker caste.

Nomenclature

 *  yamanei. Aenictus yamanei Wiwatwitaya & Jaitrong, 2011: 562, figs. 2A-D, 3 (w.) BORNEO.

Worker
Holotype and paratype workers (n = 10): TL 3.70-3.80 mm; HL 0.83-0.85 mm; HW 0.63-0.70 mm; SL 0.68-0.73 mm; ML 1.22-1.27 mm; PL 0.32-0.35 mm; CI 79-85; SI 96-103.

(holotype and paratypes). Head in full-face view clearly longer than broad, with sides feebly convex and posterior margin almost straight or feebly concave. Head from the tip of frontal carina to occipital margin longitudinally and very shallowly impressed. Antennal scape extending posteriorly beyond 3/4 of headlength. Frontal carina not reaching midlength of head, and well developed anteriorly and poorly developed posteriorly; parafrontal ridge present extending posteriorly by less than 1/3 of head length; in profile its anteriormost part raised as a subtriangular process, and poorly developed posteriorly. Clypeus short, its anterior margin convex, lacking denticles. Mandible broad and triangular, its masticatory margin with a large apical tooth followed by a small subapical tooth and a series of about 19-20 minute denticles of two sizes, the larger alternating with 4-6 smaller; basal margin of mandible lacking denticles. Mososoma relatively stout; promesonotum seen in profile strongly convex dorsally and sloping gradually to metanotal groove; mesopleuron clearly demarcated from metapleuron by a deep groove; anepisternum clearly demarcated from katepisternum by a deep groove. Propodeum in profile with almost striagth dorsal outline; propodeal junction acutely angulate; declivity of propodeum shallowly concave, and encircled with a rim; opening of propodeal spiracle clearly circular with its diameter about 2.3 times as long as diameter of postpetiolar spiracle. Petiole slightly longer than high, its dorsal outline elevated posteriorly, posterior face of petiole shallowly concave, and encircled with a carina; subpetiolar process large with anterior corner rounded, posteroventrally produced into an arm with a blunt tip; margin connecting anterior corner and the tip of the arm almost straight. Postpetiole clearly longer than petiole, its dorsal outline roundly convex.

Head, mesosoma, petiole, and postpetiole densely punctate and opaque; antennal scape micropunctate; mandible extensively puncto-striate, with outer zone, apical portion and masticatory margin rather smooth and shiny. Proprodeal dorsum with a few short longitudinal ridges in front of junction. Gastral segment I with fine and superficial reticulation, subopaque and slightly shining. Punctation on femora weaker than on head and mesosoma; tibiae of legs entirely micropunctate.

Head with a pair of long standing hairs mixed with relatively dense short hairs over the surface; mesosoma with relatively sparse long standing hairs mixed with dense short hairs over the surface; length of the longest pronotal hair 0.38-0.40 mm. Entire body dark reddish-brown.

Type Material
Holotype. Worker from Niah N. P., Sarawak, Borneo, Malaysia, 9 I 1993, Sk. Yamane leg. . Nine paratype workers, same data as holotype (, and ).

Etymology
The specific name is dedicated to Prof. Seiki Yamane of Kagoshima University, Japan.