Strumigenys thaxteri group

Strumigenys thaxteri group Bolton (2000)

Worker Diagnosis
Mandibles in full-face view and at full closure subtriangular, broad and powerfully developed, their dorsal surfaces convex from apical to lateral margin and their lateral outlines distinctly convex. Masticatory margins serially dentate and the tooth rows engage through the lengths of the margins. In profile masticatory margin of mandible distal of clypeus arched-down-curved. In ventral view outer margin of mandible without an inflected prebasal angle. MI 7-22.

Dentition. Mandible with 12-13 sharp but quite small narrowly triangular teeth on the broadly arched masticatory margin. Basal 8-9 teeth larger than those situated more distally; apical tooth larger than those immediately preceding it.

Basal lamella of mandible (thaxteri) long and deep, subrectangular, truncated apically and almost as high as the basal series of teeth. Lamella incorporates lower half of basal tooth, which arises from its anterior margin; not visible in full-face view when mandibles are fully closed.

Labrum terminates in a pair of bluntly triangular to digitate lobes.

Clypeus with anterior margin broad and extremely feebly sinuate, almost transverse (thaxteri), or with a median tooth (reticeps); lateral margins weakly divergent posteriorly and extend under the elevated anterior curvatures of the frontal lobes.

Clypeal dorsum with erect curved hairs or with subappressed to appressed fine curved simple hairs.

Preocular carina not visible in full-face view, concealed by the expanded frontal lobe.

Ventrolateral border of head marginate in front of eye, the margination shallowly concave and terminating anteriorly in an acute triangular tooth. Postbuccal impression inconspicuous.

Cuticle of side of head within scrobe densely reticulate-punctate. Eyes prominent and bulging outwards.

Scape short, SI 55-63, stout in dorsal view; leading edge sharp and ventral surface shallowly concave.

Leading edge of scape evenly shallowly convex, with abundant fine soft short hairs that are all curved toward the base of the scape (thaxteri).

Pronotal humeri prominent and angular in dorsal view.

Propodeum armed with a pair of elongate but broad-based acute teeth, subtended by narrow lamellae.

Spongiform appendages present on petiole and postpetiole. Base of first gastral sternites with a diffuse spongiform pad.

Pilosity. Pronotal humeral hair absent or present. All dorsal surfaces of head and body densely clothed with soft flexuous to flagellate fine hairs. All surfaces of legs with freely projecting fine hairs.

Sculpture. Dorsum of head behind clypeus with fine dense reticulate-rugulose sculpture, at least in part. Sides of alitrunk unsculptured. Basigastral costulae faint, almost effaced.