Taxonomy. Although the genus Temnothorax was synonymized with Leptothorax, Temnothorax was recently revived as an independent genus by Bolton (2003) and assigned to the Temnothorax genus group of the tribe Formicoxenini . Workers of Vietnamese species have the following features.
Worker monomorphic. Head subrectangular with round posterior corners; frontal carina and antennal scrobe absent; median portion of clypeus moderately convex anteriad, but never forming an anteriorly projecting shelf and never distinctly overlapping basal portion of mandibular blades; median clypeal carina weak but present; medianclypeal seta absent; posteromedian portion of clypeus broadly inserted between frontal lobes; mandible triangular, with 5 teeth; palp formula 5,3; stipes of maxilla without a transverse crest at about its midlength; antenna 12-segmented, with 3-segmented antennal club; eye moderate to large in size; promesonotum in lateral view only weakly raised; promesonotal suture absent dorsally; metanotal groove shallowly impressed or almost absent dorsally; propodeal spine present; propodeal lobe roundly expanded; middle and hind tibiae without distinct spurs apically; petiole pedunculate, with low node, with a tiny process or angle on ventral face of anterior part of peduncle; gastral shoulder weakly present; sting simple, without any appendix apically.
Vietnamese species. Two species are known from Vietnam: sp. eg-1 (Sa Pa); sp. eg-2 (Tam Dao).
Bionomics. Temnothorax species are rare in Vietnam where they have been collected around or above 1000 m alt. in northern Vietnam.