Strumigenys schulzi group

Strumigenys schulzi group Bolton (2000)

Species
Strumigenys madrigalae

Worker Diagnosis
Mandibles in full-face view and at full closure triangular, with serially dentate masticatory margins that engage throughout their exposed lengths. In ventral view outer margin of mandible without a prebasal inflected angle. MI 10-24.

Dentition. Basally with a row of 5 teeth followed by 2 smaller teeth and 4 denticles, or with 5 teeth and 4 denticles only; terminating in a slightly enlarged apical tooth, giving a total dental count of 10 or 12. Usually no diastema between basal lamella and basal tooth, only rarely otherwise. [Dental rows are variously specialised in different species; see discussion below.]

Basal lamella lobate to rounded-triangular, as high as long or somewhat higher; less commonly low and elongate-rectangular, longer than high. Lamella of about equal height to the tallest teeth or slightly lower. In full-face view at least the anterior margin of the lamella usually visible when mandibles fully closed.

Labrum terminates in a pair of elongate narrowly triangular to conical lobes.

Clypeus with anterior margin very shallowly concave, transverse or evenly shallowly convex. Lateral margins straight to shallowly convex and weakly divergent posteriorly. Outer margins of fully closed mandibles intersect anterior clypeal margin at about the anterolateral angles, or continue just outside the lateral margins in full-face view (1 species).

In ventral view the lateral clypeal margins usually extend slightly beyond the outer margins of the mandibles.

Clypeus dorsally with decumbent to appressed short spatulate to squamate hairs that are directed anteriorly (minute elevated hairs occur in some species). Lateral margins of clypeus fringed by a row of freely projecting spatulate hairs that are curved anteriorly.

Preocular carinae visible in full-face view.

Ventrolateral margin of head angulate to marginate between eye and mandibular insertion.

Postbuccal impression narrow and shallow.

Cuticle of side of head within scrobe reticulate-punctate.

Scape short to moderate, SI 50-82, very feebly to markedly dorsoventrally flattened, dorsum and ventre converging anteriorly to a sharp leading edge that may extend into a flange or even a thin lamella. Ventral surface of scape flat to shallowly transversely concave.

Leading edge of scape with a row of freely projecting spatulate to spoon-shaped hairs, one or more of which curve toward the base of the scape (in three species all hairs spoon-shaped, at right-angles to long axis of scape or inclined toward apex of scape and slightly down-curved).

Propodeum armed with a pair of triangular teeth subtended by lamellae, the latter sometimes very narrow and cariniform.

Spongiform strip or curtain usually absent from ventral surface of petiole (present but narrow in two species); a low non-spongiform cuticular crest may occur. Lateral spongiform lobe of petiole node small, sometimes vestigial or even absent. Lateral and ventral spongiform lobes of postpetiole present but may be very reduced. Base of first gastral sternite in profile with a narrow spongiform pad or strip (vestigial to absent in a few species).

Pilosity. Pronotal humeral hair either absent, or straight to curved and simple to somewhat thickened apically, or large and spoon-shaped, but never flagellate. Apicoscrobal hair absent, or curved and stout; never flagellate. Dorsum of head in profile usually with a transverse row of 4-6 standing hairs between highest point of vertex and occipital margin, these hairs distinctly longer and more erect that any other component of the cephalic pilosity (absent in some species). Dorsal (outer) surfaces of middle and hind tibiae with decumbent to appressed short spatulate hairs only, or with abundant short stubbly erect hairs (l species).

Sculpture. Dorsum of head behind clypeus and dorsal alitrunk with fine dense reticulate-punctate sculpture; rarely part or all of pleurae smooth but this area usually also entirely sculptured. Postpetiole usually densely sculptured, rarely smooth.