Strumigenys substricta group

Strumigenys substrica group Bolton (2000)

Species

Neotropical

Worker Diagnosis

Mandibles in full-face view and at full closure short and powerful, masticatory margins engage throughout their lengths. In profile dorsal surface distal of clypeus curved or arched-down-curved, proximally rising above the level of the anterior clypeus. In ventral view outer margins of mandibles divergent from apex to level of anterior clypeal margin where they pass through a rounded prebasal angle, proximal of which the outer margins are approximately parallel to their bases. MI l l-20.

Dentition. With 7-8 stout triangular to low-conical teeth that are very slightly recurved, immediately following the basal lamella. Distal of tooth 7 or 8 is a smaller tooth and 1-3 denticles, giving a total dental count of 10-12. Basal lamella broad, either high and truncated apically or lower and more rounded; tooth row follows lamella without a diastema. Lamella not or partially visible in full-face view when mandibles closed.

Labrum terminates in a pair of long spatulate, almost strap-like, flat lobes that are bluntly rounded apically and strongly divergent in a marked V-shape from base to apex. Clypeus with anterior margin deeply concave; lateral margins projecting far beyond outer margins of mandibles and posteriorly confluent with the vastly expanded frontal lobes. In full-face view the outer mandibular margins intersect the anterior clypeal margin a considerable distance mesad of the clypeal anterolateral angles. Clypeal dorsum with minute appressed pubescence only; clypeal margins without projecting hairs of any form.

Frontal lobes and frontal carinae enormously expanded laterally, projecting out over the ventrolateral margins and completely concealing the latter throughout their length. Preocular carina not visible in full-face view because of massive expansion of frontal lobe and frontal carina.

Ventrolateral margin of head sharply marginate in front of eye, margination may terminate anteriorly in an acute angle or small tooth. Postbuccal impression very shallow and not involving the ventrolateral margination.

Cuticle of side of head within scrobe mostly or entirely smooth and shining.

Scape very short, SI 40-50, very feebly dorsoventrally flattened, its leading edge distal of the subbasal bend evenly shallowly convex.

Leading edge of scape appearing hairless, at most with a few minute closely appressed hairs that are directed toward the apex of the scape.

Head in profile extremely dorsoventrally flattened.

Pronotum not or weakly marginate dorsolaterally.

Petiole node in dorsal view longer than broad, in profile height of anterior face of node shorter than length of dorsum.

Spongiform appendages of waist segments fully represented and large. Base of first gastral sternite in profile with a spongiform pad.

Pilosity. Pronotal humeral hair present or absent. Dorsal (outer) surfaces of middle and hind tibiae with closely appressed small hairs only.

Sculpture. Dorsum of head behind clypeus and entire alitrunk without reticulate-punctate sculpture.

Notes

The two very specialised species in this group are easily diagnosed. They retain large spongiform appendages on the waist segments and lack a broadly U-shaped or V-shaped postpetiole but have developed extremely flattened broad heads (the head is obviously more than twice wider than deep), have enormously expanded frontal carinae, long spatulate labral lobes that diverge in a V-shape, anteriorly concave extremely broad clypeus and a petiole node that is longer than broad.

References

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