Technomyrmex formosensis

The species is only known from Taiwan. The type material was found in a nest in decayed wood and one of the non-type collections was made from a nest under a stone.

Identification
A member of the Technomyrmex bicolor group.

Yamane et al. (2018) - TL 2.5–3.5. Scape long; SI>1.30. Propodeal dorsum rounded into declivity, without distinct angle between them; straight-line length of propodeal dorsum less than length of declivity to spiracle. Metathoracic spiracle located close to metanotal groove; distance between them usually around one spiracle diameter. Body almost entirely dark brown to black except for legs, which are partly whitish or yellowish, and mid- and hind coxae milky white.

Technomyrmex formosensis is in coloration and structure very similar to Technomyrmex kraepelini inhabiting the Sundaland region (syntype images examined; AntWeb, 2017). However, it is distinguished from the latter by a more slender body and longer antennal scape. Scape index is always more than 125 (up to 132) in the former, while it is constantly less than 125 (minimum 90) in the latter. The dorsum of the propodeum roundly convex, with no angle between it and the declivity in the former, while the propodeum has a more or less flat dorsal surface, with a rounded angle with the declivity in the latter. The present new species is also similar to Technomyrmex antennus Zhou, 2000 from southern China (Zhou, 2000) in some respects such as the short dorsum of the propodeum and long antennae. However, in Technomyrmex antennus the body colour is reddish brown as in Technomyrmex horni (dark brown to black in T. formosensis), propodeal junction is angled (without angle in the latter), and the antennae and legs are yellowish brown (mainly black in the latter).

Distribution based on Regional Taxon Lists
Oriental Region: Taiwan.

Nomenclature

 *  formosensis. Technomyrmex formosensis Yamane, Leong, & Lin, 2018: 47, figs. 11, 12 (w.) TAIWAN.

Worker
n=10 including holotype; values for holotype are in parentheses - TL 2.5–3.5, HW 0.69–0.76 (0.69), HL 0.78–0.89 (0.80), SL 0.88–0.99 (0.91), EW 0.15–0.18 (0.17), EL 0.20–0.24 (0.22), PrW 0.46–0.54 (0.46), MsW 0.28–0.36 (0.29), CI 85–89 (86), SI 127–132 (132). Head seen in full-face view longer than broad, with weakly convex lateral margin and almost straight to shallowly emarginate posterior margin, broadest at level of eye. Clypeus posteriorly demarcated from frons by weak suture, anteriorly broadly emarginate forming large lateral lobes; inner margin of this emargination smoothly meeting with anterior margin of clypeus (lobe) without angle. Eye located slightly in front of midlength of head; its outer margin approaching lateral margin of head but not breaking the latter; distance between anterior margin of eye and mandibular base subequal to eye length. Antennal scape surpassing posterior margin of head by 2/5 of its length or more. Pronotum in dorsal view much longer and broader than mesonotum; posterolateral corner of pronotum produced backward. With mesosoma in profile, mesonotum sloping from level of pronotum toward metanotal groove; mesopleuron not differentiated from mesonotum. Metanotal groove distinct; metathoracic spiracle close to groove (anterior margin of propodeum), distance separating them one spiracle diameter or slightly more. Propodeum in profile with dorsal margin convex and gradually rounded into declivity; no distinct angle present between dorsum and declivity; straight-line length of dorsum less than length of declivity to spiracle. Head very finely and densely puncto-reticulate and mat; sculpture weaker on venter of head and legs; mesosoma with stronger and coarser puncto-reticulation than on head. Sculpture on mandible and lower part of propodeal declivity much weaker. Petiole smooth and shiny. Dorsum of cranium without standing hairs; clypeus with two pairs of long hairs arising from anterior margings of lateral lobes. Mesosoma without standing hairs. Gastral tergites 2–4 each with 2 pairs of long hairs. Body dark brown to black. Mandible light brown; flagellum and legs rather reddish. Trochanters of all legs and mid- and hind coxae whitish; both extremities of femora, and tarsi of all legs yellowish.

Type Material
Holotype worker: Sun Moon Lake (760 m alt.), ca. 23.8574°N, 120.9384°E, 5.vii.2017, nest in decayed wood (Sk. Yamane leg., TW17-SKY-39), unique specimen identifier YLL01. Paratype workers: 12 workers from the same colony [NMNS,, TFRI, unique specimen identifiers YLL02–13.