Aenictus leptotyphlatta

Identification
A member of the leptotyphlatta group. Jaitrong & Eguchi (2010) - A set of  Aenictus  species with typhlatta spots on the head can be divided into 2 groups. First are those in the Aenictus laeviceps group (Aenictus alticola, Aenictus binghami, Aenictus fergusoni, Aenictus laeviceps, and Aenictus luzoni). They share the following character conditions: anterior clypeal margin roundly convex with several conspicuous denticles; head in full-face view with occipital corner rounded; in profile typhlatta spot usually located anterior to occipital comer; subpetiolar process well developed, with the apex directed downward and backward. Second are is the Aenictus gracilis group species (Aenictus cornutus, Aenictus currax, Aenictus diclops, Aenictus gracilis, and Aenictus huonicus). All these species share the following character conditions: clypeal margin roundly convex, lacking denticles; head in full-face view with occipital comer convex, with a distinct protuberance which gives the head a unique “horned” appearance; in profile “typhlana spot” always located at occipital corner; subpetiolar process weakly developed. A. leptotyphlatta exhibits conditions intermediate between the two groups. It has the anterior clypeal margin lacking denticles as in the A. gracilis group but the occipital comer of the head similar to that of the A. laeviceps group. Furthermore the typhlatta spot is less developed, much paler in coloration than in the other typhlatta-bearing species. It is the smallest among the species with typhlatta spots, which are distributed in the Oriental, Indo-Australian, and Australasian regions, and is similar to A. alticolus in the shape of the subpetiolar process (large and angulate with the apex directed downward). However, the latter is much larger and has the clypeus provided with denticles on its anterior margin.

Key to Aenictus species groups

Distribution based on Regional Taxon Lists
Oriental Region: Thailand.

Castes
Known only from the worker caste.

Nomenclature

 *  leptotyphlatta. Aenictus leptotyphlatta Jaitrong & Eguchi, 2010: 14, figs. 1, 2 (w.) THAILAND.

Worker
Holotype and nine paratype workers (n = 10): TL 2.35-2.45 mm; HL 0.50-0.53 mm; HW 0.43-0.48 mm; SL 0.33-0.35 mm; ML 0.73-0.78 mm; MTL 0.38-0.45 mm; PL 0.1 8-0.20 mm; CI 85-90; SI 74-76.

Worker Description (holotype and para types). Head in full-face view subrectangular, longer than broad, with slightly convex sides and almost straight or very weakly concave posterior margin. Occipital margin of head lacking collar. Antenna 10-segmented; antennal scape short, reaching or little extending beyond the half length of head; antenna I segments II-X each longer than broad; II longer than each of III-VI; VII, VIII and IX combined shorter than the terminal segment (X). Frontal carina short and thin extending posteriad, not beyond the level of posterior margin of torulus; anterior curve of frontal carina reaching or extending beyond anterior clypeal margin. Clypeus short, its anterior margin lacking teeth; median portion of anterior clypeal margin slightly convex and protruded anteriad. Mandible subtriangular with a large apical tooth followed by 4-5 relatively large teeth on masticatory margin; basal margin of mandible sinuate with a series of 3-5 ill-defined denticles.

Mesosoma in profile with promesonotum weakly convex dorsally and sloping gradually to propodeum. Mesopleuron rather long; anepisternum demarcated from katepisternum by a groove. Propodeal junction convex or somewhat obtusely angulated; propodeal declivity laterally margined with a thin rim; opening of propodeal spiracle clearly circular with its diameter 1.5-2.0 times as long as diameter of petiolar spiracle; area below propodeal spiracle impressed; metapleural gland bulla 0.13-0.15 mm in maximum diameter, almost as long as postpetiolar node. Petiole narrow, seen from above almost parallel-sided; in profile its node distinctly longer than high, round dorsally; subpetiolar process well developed and triangular with the apex directed downward. Postpetiole clearly shorter than petiole; its node almost as long as high.

Gaster elliptical, narrowed anteriorly and posteriorly, in dorsal view 0.43-0.45 mm in maximum width.

Head and antennal scape smooth and shiny. Dorsum of mesosoma entirely smooth and shiny; mesopleuron with 10-12 longitudinal rugae and dense micropunctures; lower portion of metapleuron with dense micropunctures; propodeum almost smooth and shiny. Petiole and postpetiole smooth and shiny. Gaster, and femora and tibiae of all legs smooth and shiny.

Body with relatively sparse standing hairs; length of the longest pronotal hair 0.13-0.15mm.

Head reddish brown or dark brown; mesosoma black or dark brown; petiole, postpetiole and gaster dark brown or reddish brown; Antenna! scape reddish brown or dark brown except at the base and apex yellowish brown; funiculus of antenna yellowish brown; mandible yellowish brown; legs reddish brown; typhlatta spot present but not clear.

Type Material
Holotype: worker from the Campus of Chiang Mai University, Chiang Mai province, northern Thai land, 10 VI 200 I, W. Jaitrong leg., WJTOI-CMUOI. Paratypes: 63 workers, same data as holotype; additional 10 workers collected from the same colony by K. Eguchi on the same day (Eg01-TH-158) (,, , , , , , THNHM).