Strumigenys talpa group

Strumigenys talpa group Bolton (2000)

Species

Nearctic

Worker Diagnosis

Mandibles in full-face view and at full closure triangular, teeth engage through length of dentate margin but a distinct basal lamella or edentate basal diastema is present between basal tooth and anterior clypeal margin . In ventral view outer margin of mandible without an inflected prebasal angle. MI 15-19.

Dentition. Principal dental row with 4 sharp teeth . Tooth 1 (basal) and 2 subequal in size, with 1 usually slightly recurved or inclined proximally; either 1 or 2 the longest on the margin. Tooth 2 always longer than 3; tooth 4 usually also longer than 3. Tooth 4 followed by two smaller teeth, 4 minute denticles and a small apical tooth, giving a total dental count of 11.

Basal lamella of mandible triangular, broad-based and higher than the longest tooth, not visible to extensively exposed in full-face view with the mandibles fully closed.

Basal lamella adjacent to basal tooth or separated from it by a marked diastema that is longer than the basal tooth.

Labrum terminates in a pair of narrow digitate to conical lobes.

Clypeus with anterior margin broadly and evenly convex. Lateral clypeal margins feebly convex, weakly convergent anteriorly. In ventral view the lateral clypeal margins extend beyond the outer margins of the fully closed mandibles. Clypeus without peripheral groove.

Clypeal lateral margins with a fringe of spoon-shaped, spatulate or weak filiform hairs that may be curved anteriorly or reflexed. Anterior margin with smaller hairs that are curved toward or away from the midline. Clypeal dorsum with spatulate hairs, without any other form of pilosity.

Preocular carina broad and conspicuous in full-face view.

Ventrolateral margin of head between eye and mandible bluntly marginate. Postbuccal impression small and shallow.

Cuticle of side of head within scrobe reticulate-punctate.

Scape short to moderate, SI 66-78, moderately dorsoventrally flattened and with a sharp leading edge.

Leading edge of scape with elongate narrowly spatulate hairs, all of which are curved toward the apex of the scape.

Propodeum with triangular teeth subtended by a lamella on each side that is sometimes broad and engages the teeth through most of their length.

Spongiform appendages well developed on petiole and postpetiole; ventral spongiform curtain of petiole well developed . Base of first gastral sternite in profile with a band or pad of spongiform tissue that may be weak or diffuse.

Pilosity. Pronotal humeral hair usually elongate and sinuate or flagellate. Dorsum of head behind clypeus with filiform to narrowly spatulate ground-pilosity. Dorsolateral margin of head with 1-2 freely projecting flagellate hairs. First gastral tergite with long fine flexuous to flagellate hairs. Dorsal (outer) surface of hind basitarsus with 1-2 long fine flagellate hairs.

Sculpture. Dorsum of head behind clypeus reticulate-punctate. Pleurae, side of propodeum and disc of postpetiole smooth.

Notes

This small group is very much as Brown (1953a) left it, except for the addition of archboldi and the transfer of creightoni from here to the pulchella group. The latter is because creightoni shows hairs on the leading edge of the scape that curve toward the base of the scape, a universal character of the pulchella-group that is not developed in talpa-group species, where all scape hairs on the leading edge curve toward the apex.

References

Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.
Brown, W. L., Jr. 1953a. Revisionary studies in the ant tribe Dacetini. American Midland Naturalist. 50:1-137.