Myrmecina asthena

Identification
Okido, Ogata, and Hosoishi (2020) -  Myrmecina asthena is similar to Myrmecina lombokensis in head sculpture, relative length of the antennal scape, process of the clypeus, and shape and sculpture of the first gastral segment. It stands apart by its small and circular eye of around 6 ommatidia.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Malaysia. Oriental Region: Vietnam. Palaearctic Region: China.

Nomenclature

 * . Myrmecina asthena Okido, Ogata & Hosoishsi, 2020: 21, fig. 6 (w.) CHINA.

Worker
Holotype. TL 3.07, HL 0.72, HW 0.62, CI 87, SL 0.54, SI 87, PW 0.43, ML 0.77. Paratype. TL 2.86-2.98, HL 0.64-0.69, HW 0.56-0.61, CI 86-88, SL 0.51-0.56, SI 87-92, PW 0.38-0.42, ML 0.74-0.78 (5 measured).

Head subrectangular, longer than broad distinctly in full-face view; median portion of occipital margin concave; occipital corners rounded, not projected posteriorly. Masticatory margin of mandible bent at midlength (third small tooth or sixth tooth); apical tooth strong, third tooth robust, followed by 5 small teeth and a basal tooth. Dorsal surface of clypeus not concave; median portion of anterior margin feebly projected, with or without three processes; lateral portion simple, lacking sharp ridge in front of antennal insertions. Anterior dorsal surface of labrum with paired small denticles, which are well separated. Frontal carinae absent. Eyes extremely small circularly and not convex, varying in size with maximum diameter 0.05-0.06 mm and 5-8 ommatidia; malar space three times as long as diameter of eye or longer in profile; distance between occipital margin and posterior margin of eye distinctly five times as long as diameter of eye or longer. Antennal scape short, just reaching posterolateral corner of head; antennal flange developed.

Dorsal outline of mesosoma convex to flattened in profile. Pronotum without denticles; anterior portion not marginate completely in dorsal view; anterior ventrolateral portion not angulate. Mesoepisternal projection reduced; cleavage between pronotum and mesoepisternal projection broad. Eumetanotal spine present but small. Propodeal spine triangular, variable in length, usually extending over vertical posteriormost limit of propodeum in profile. Propodeal lobe low. Propodeal spiracle large, situated near base of propodeal spine, apart from margin by its diameter. Petiole long, longer than high in profile, and longer than broad in dorsal view; dorsal crest located at midlength in profile; subpetiolar process with acute anterior apex, or median longitudinal ridge at ventral portion present. Postpetiole slightly broader than petiole in dorsal view; dorsal outline flattened in profile; ventral outline clearly projected rectangularly with acute anterior apex.

Anterior margin of gaster not concave in dorsal view.

Head densely punctured sometimes with unclear longitudinal rugae; ventrolateral portion usually punctured, rarely unclearly. Clypeus smooth and shining. Mesosoma with thin and straight rugae weakly. Forecoxa smooth and shining. Petiole and postpetiole with longitudinal rugae. First gastral segment smooth and shining. Head with dense and short pilosity on dorsum. Mesosoma with dense and short pilosity on dorsum, hairs of pronotum shorter than propodeal spine. Petiole without hairs on ventral surface. Postpetiole with 4 hairs on ventral surface. Body black to reddish brown, mandibles, antennae and legs yellowish brown.

Type Material
Holotype worker, CHINA: Dabei, 2440 m alt., Gaoligongshan Mts., Tengchong Xian, Yunnan Prov., 11. x. 1996 (S. Nomura). Paratypes. 11 workers with same data as holotype. CHINA: 1 worker, Dahaoping Gaoligongshan Mts., Tengchong Xian, Yunnan Prov., 10. x. 1996 (S. Nomura); 1 worker, Huanxipo, Tengchong Xian, Yunnan Prov., 14. x. 1996 (S. Nomura).