Strumigenys probatrix group

Strumigenys probatrix group Bolton (2000)

Species

Neotropical

Worker Diagnosis

Mandibles in full-face view and at full closure narrowly triangular to subtriangular, elongate, the outer margins straight or even slightly concave in the median third of the length. Masticatory margin dentate only in the apical third or so of its visible length, the dentate sections fully engage; margin proximal of basal tooth occupied by basal lamella. In profile mandible straight, downcurved only at extreme apex. In ventral view outer margin shallowly concave medially, without an inflected prebasal angle. MI 22-25.

Dentition. Basal lamella immediately followed by 6 narrowly triangular acute teeth beyond which is a distinctly lower seventh tooth, then 4 denticles and a slightly larger apical tooth, giving a total dental count of 12.

Basal lamella long and low, subrectangular, clearly visible in full-face view with the mandibles fully closed; length of lamella slightly greater than length of visible tooth-row and slightly lower than height of basal tooth. Basal lamella abruptly truncated distally before the basal tooth, more tapering at its proximal end. No diastema between lamella and basal tooth.

Labrum terminates in a pair of long narrow digitate lobes.

Clypeus elongate, its anterior margin narrowly convex. Lateral margins divergent posteriorly. Outer margins of mandibles visible outside lateral c1ypeal margins for most or all of their length.

Clypeal margins fringed with short simple or spatulate hairs that are more or less straight or weakly curved anteriorly. Dorsum of clypeus with small simple or spatulate hairs.

Preocular carina clearly visible in full-face view, termi nating well in front of the posteriorly placed eye; the latter also visible in this view, relatively large and convex. Frontal lobes and frontal carinae not expanded laterally.

Ventrolateral margin of head angular but not sharply marginate between eye and base of mandible, approximately straight. Postbuccal impression very shallow.

Cuticle within scrobe densely reticulate-punctate.

Scape long and subcylindrical, SI 88-97, not dorsoventrally flattened and without a sharp leading edge.

Leading edge of scape with simple to narrowly spatulate hairs that are all curved toward the apex of the scape.

Head in full-face view with the anterior two-thirds, in front of the level of the eyes, extremely long and narrow.

Propodeum with a pair of triangular teeth or spines.

Spongiform appendages fully developed; in profile the petiole with a ventral strip and lateral lobes, the postpetiole with large lateral and ventral lobes and the base of the first gastral stemite with a diffuse but conspicuous pad.

Pilosity. Pronotal humeral hair very long, flagellate. Dorsolateral margin of head behind level of eye with a long flagellate hair. Mesonotum with a single pair of flagellate hairs, and flagellate hairs also present on petiole, postpetiole and first gastral tergite.

Notes

Two very distinctive long-headed species (CI 55-62), Strumigenys doryceps and Strumigenys probatrix, currently occupy this group. The relationships of the group are unclear but the presence of dense reticulate-punctate sculpture and relatively large eyes suggests affinity with the schulzi group.

Members of this group should not be confused with any other Neotropical members of the genus. Their much elongated heads, long legs and scapes, unique structure of the mandible and long flagellate pilosity, render the species easily recognisable.

References

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