Strumigenys rostrata group

Strumigenys rostrata group Bolton (2000)

Worker Diagnosis
Mandibles in full-face view and at full closure triangular, either serially dentate with masticatory margins that engage through all their visible length or with an edentate gap present between basal tooth and anterior clypeal margin. In ventral view outer margin of mandible without an inflected prebasal angle. MI 15-25.

Dentition. Principal tooth row with 5 sharp triangular teeth. Tooth 1 (basal) and 2 subequal in size or one longer than the other, tooth 3 distinctly longer (longest tooth on margin) and 4 reduced, smaller than 3 or 5. Tooth 5 usually only slightly shorter than 3 and hence usually the second longest tooth on the margin. Tooth 5 followed by two small teeth, 4 minute denticles and a small apical tooth, giving a total dental count of 12.

Basal lamella of mandible triangular, broad-based and longer than the longest tooth, not visible to partially visible in full-face view with the mandibles fully closed. Basal lamella not separated from basal tooth or with a small to obvious diastema present (see note, below).

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

Clypeus with anterior margin broad, shallowly convex , transverse or shallowly concave in full-face view. 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 continuous fringe of anteriorly curved broadly spatulate to spoon-shaped hairs. Anterior margin with smaller hairs that are directed anteriorly or curved toward the midline. Clypeal dorsum with small 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 67-82, weakly to moderately dorsoventrally flattened, the dorsum and ventre converging anteriorly so that the leading edge is sharp or even a thin flange or lamella. Ventral surface of scape behind the leading edge usually weakly concave.

Leading edge of scape with conspicuously spatulate to spoon-shaped hairs, some of which are curved 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 narrow band or thin pad of weak or diffuse spongiform tissue that frequently appears hair-like.

Pilosity. Pronotal humeral hair usually present, elongate and straight or flagellate. Dorsum of head behind clypeus with spatulate to spoon-shaped ground-pilosity. Dorsolateral margin of head with or without an apicoscrobal hair. First gastral tergite usually with simple pilosity present, more rarely with flagellate hairs.

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