Strumigenys membranifera group

Strumigenys membranifera group Bolton (2000)

Nearctic
Strumigenys membranifera

Worker Diagnosis
Mandibles in full-face view and at full closure short triangular, serially dentate and the masticatory margins engaging throughout their length. Dorsal surface of mandible sharply depressed immediately behind the level of the basal tooth, the rim of the depression appearing as a sharp transverse edge that traverses the width of the mandible immediately behind the level of the basal tooth, and paralleling the anterior clypeal margin. The transverse edge appears to be followed proximally by a deep transverse groove or impression immediately in front of the anterior clypeal margin. In profile dorsal surface of mandible arched-downcurved from clypeal margin to apex. In ventral view outer margin of mandible with a shallowly rounded prebasal inflected angle. MI 16 - 20.

Dentition. Basally with a dental row of 7 sharply triangular teeth of which 1 - 5 are slightly taller than 6 - 7, followed distally by 4 minute denticles and a slightly enlarged apical tooth, giving a total dental count of 12.

Basal lamella of mandible truncated-triangular, not in the same plane as the principal basal dental series but located below and slightly behind the basal tooth; not visible in full-face view with the mandibles closed.

Labrum terminates in a pair of narrow elongate triangular lobes.

Clypeus with anterior margin broad, transverse to extremely shallowly convex. Lateral margins of clypeus approximately straight and more or less parallel. Anterolateral clypeal angles located much further laterally than the point at which the outer margins of the mandibles intersect the anterior clypeal margin.

Clypeal margins and dorsum with minute appressed pubescence only, appearing naked under normal magnifications. In ventral view the lateral clypeal margins extending well beyond the outer margins of the fully closed mandibles through the basal third or more of their length.

Preocular carina visible anteriorly in full-face view but behind level of frontal lobes concealed from view by frontal carina.

Ventrolateral margin of head between eye and mandible marginate, the margination curving shallowly upward anteriorly from the eye; not terminating anteriorly in a tooth. Postbuccal impression small and inconspicuous.

Cuticle of side of head within scrobe finely shagreenate or punctulate.

Scape short, SI 51 - 57, dorsoventrally flattened, the dorsum and ventre converging anteriorly so that the leading edge is a sharp flange or even a thin lamella. Ventral surface of scape behind the leading edge concave.

Leading edge of scape with a row of large spatulate hairs, one or more of which are curved toward the base of the scape.

Pronotum sharply marginate laterally, without a median longitudinal carina.

Propodeum with a broad lamella running down the declivity; lamella incorporating the propodeal teeth which are indistinguishable except for a minute apical point.

Spongiform appendages massively developed on waist segments. Base of first gastral stemite in profile with a distinct pad of dense spongiform tissue.

Pilosity. Pronotal humeri without projecting hairs of any description. A single pair of feebly clavate hairs present at highest point of vertex, otherwise dorsolateral and dorsal surfaces of head without standing pilosity; apicoscrobal hair absent. Dorsal surfaces of alitrunk, waist segments and first gastral tergite without standing pilosity. Ground-pilosity of head minute, sparse and appressed, very inconspicuous.

Sculpture. Dorsum of head behind clypeus finely reticulate-punctate. Dorsum and sides of alitrunk mostly to entirely smooth and shining; disc of postpetiole smooth.