Strumigenys decollata group

Strumigenys decollata group Bolton (2000)

Species

Malesian-Oriental-East Palaeartic

Worker Diagnosis

Apical fork of mandible with 2 teeth, a small intercalary tooth between them. Mandible with 2 preapical teeth; a spiniform distal tooth at about one-third the length from the apicodorsal tooth, and a much smaller proximal tooth that is proximal to the mandible midlength. MI 52-58.

Anterior clypeal margin shallowly to deeply concave medially.

Scape moderate, SI 87, stout and straight, very slightly dorsoventrally flattened.

Apical antennomere slightly tapered basally but not spindle-shaped.

Ventrolateral margin of head without a preocular notch; postbuccal groove almost effaced.

Head long and narrow (CI 60-63), the ventral surface without transverse impressions.

Propodeal teeth minute to short-triangular, subtended by a narrow lamella whose posterior (free) margin is concave.

Petiole node in profile long and low, the dorsum of the node longer than the peduncle; in dorsal view the node much longer than broad.

Spongiform appendages of waist segments all present but mostly reduced. Petiole ventrally with a narrow spongiform strip; lateral lobe of petiole hardly more than a slight expansion of the posterior collar. Ventral lobe of postpetiole of moderate size but lateral lobe mostly a mere fringe around the margin of the tergite, broadest at posterolateral corner. Base of first gastral sternite with a spongiform pad.

Pilosity. Almost entirely absent. Apicoscrobal and pronotal humeral hairs absent. Cephalic dorsum with four short erect hairs along occipital margin. Dorsal surfaces of alitrunk, petiole and first gastral tergite without standing hairs of any form; postpetiole with a single pair of standing hairs posteriorly. Hind tibia and basitarsus without erect hairs.

Sculpture. Disc of postpetiole and first gastral tergite unsculptured; basigastral costulae absent from tergite proper but present on limbus.

Notes

Both species of this group are known only from their type-collections. The preapical dentition is unique for the region. It parallels the dentition commonly developed in the Neotropical mandibularis group, but otherwise the two groups have little in common. Other species in the Oriental and Malesian regions which possess two preapical teeth belong either to the rogeri group or the scotti group, both of which are pre-eminently Afrotropical and Malagasy. In species of these groups the proximal preapical tooth is longer than the distal, and both teeth are confined to the apical third of the length of the mandible.

References

Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.