Strumigenys pulchella group

Strumigenys pulchella group Bolton (2000)

Species

Nearctic

Neotropical

Strumigenys dispalata

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 is present between basal tooth and anterior clypeal margin. In ventral view outer margin of mandible without an inflected prebasal angle. MI 12-22.

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 and 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 almost fully 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 transverse to broadly shallowly convex. Lateral clypeal margins approximately straight to convex , and weakly to distinctly convergent anteriorly. In ventral view the lateral clypeal margins extend well beyond the outer margins of the fully closed mandibles. Clypeus without peripheral groove.

Clypeal lateral margins with a fringe of broadly spatulate to spoon-shaped hairs that may be curved anteriorly or reflexed. Anterior margin with smaller hairs that are directed anteriorly or curved toward the midline, or with 1 - 2 pairs immediately above the mandibles that are curved outwards. Clypeal dorsum with spatulate or spoon-shaped 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 to quite sharply marginate.

Postbuccal impression small and shallow to vestigial.

Cuticle of side of head within scrobe reticulate or reticulate-punctate.

Scape short to moderate, SI 65-82, not or only moderately dorsoventrally flattened but the leading edge usually sharp or even a thin flange or lamella.

Leading edge of scape with conspicuously spatulate to spoon-shaped hairs, some of which are curved or inclined toward the base 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 present, rarely absent; when present either elongate and straight or flagellate. Dorsum of head behind clypeus with simple, spatulate or spoon-shaped ground-pilosity. Apicoscrobal hair present or absent. First gastral tergite usually with simple pilosity present, more rarely with flagellate hairs. Dorsal (outer) surface of hind basitarsus usually with 1-2 long fine flagellate hairs, rarely absent.

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

Notes

Eight species of the group are known from the U.S.A., a ninth species (dispalata, related to metazytes) occurs in Veracruz state of Mexico. Of the U. S. A. species four (memorialis, missouriensis, pulchella, reflexa) have recurved or reflexed hairs on the anterior and/or lateral clypeal margins and are compared under pulchella. The remaining four (abdita, creightoni, talpa, metazytes) completely lack recurved or reflexed hairs on the clypeal margins and are discussed under creightoni. The first complex of species formed Brown's (1953a) original concept of this group. Of the present additions Brown treated abdita as a species not attached to any particular group and included creightoni in the talpa group; the other three, talpa, memorialis and metazytes, were not known at that time.

The sole Central American species referable to the group, Strumigenys dispalata, from Veracruz state in Mexico, is easily distinguished by its pulchella-group dental pattern, which is unique in the fauna of the area.

References

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