Strumigenys ornata group

Strumigenys ornata 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 edentate basal gap present between basal tooth and anterior clypeal margin. In ventral view outer margin of mandible without an inflected prebasal angle. MI 11-15.

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 longer than the longest tooth, not visible in full-face view with the mandibles fully closed. Basal lamella separated from basal tooth 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 narrowly convex to bluntly pointed; clypeus at least as long as broad. Lateral clypeal margins convergent anteriorly, not extending far beyond the line of the outer margins of the fully closed mandibles. Clypeus without peripheral groove.

Clypeal lateral margins with sparse elongate proj ecting hairs that are thick and either simple, weakly remiform or clavate apically; these hairs directed outwards or weakly curved anteriorly or posteriorly. Anterior margin with pair of hairs closest to midline curved away from the midline. Clypeal dorsum with spatulate bizarre pilosity (see under individual species).

Preocular carina broad and conspicuous in full-face view.

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

Cuticle of side of head within scrobe reticulate-punctate.

Scape moderate, SI 70-83, weakly to moderately dorsoventrally flattened and with a blunt to sharp leading edge.

Leading edge of scape with elongate narrowly spatulate hairs that may be curved toward the apex of the scape or at right-angles to long axis of scape; no hairs curved toward base of scape.

Propodeum with triangular teeth subtended by a lamella on each side.

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.

Pilosity. Pronotal humeral hair present, fine and flagellate. Dorsum of head behind clypeus with filiform to narrowly spatulate ground-pilosity. Apicoscrobal flagellate hair present. First gastral tergite with 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

The three species of this distinctive North American group are easily differentiated as each has a characteristic form of pilosity on the clypeus.

References

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