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Strumigenys tanymastax group
Strumigenys tanymastax group Bolton (2000)
Species
Neotropical
Worker Diagnosis
Mandibles in full-face view and at full closure elongate and narrow, sublinear and tapering apically. Less than the apical half of the exposed mandible dentate and mandibles only engage in this zone. Proximal of the teeth slightly more than half the mandible length edentate and in this zone mandibles separated by a broad gap through which the labral lobes are visible. In profile about the distal third or so of the dorsal margin shallowly convex, more strongly down curved apically. In ventral view outer margin of mandible without an inflected prebasal angle.
Dentition. Long edentate section of mandible distal of basal lamella terminates in a first (basal) tooth that is larger than any other on the margin except for the apical. Teeth 1, 3, 5, gradually decrease in size but each is slightly taller than the teeth 2, 4, and 6 that follow them. The small tooth 7 is followed by 4 minute denticles and an apical tooth, giving a total dental count of 12.
Basal lamella tall and broad, bluntly triangular, much taller than any of the teeth and its basal width about equal to the distance between teeth 1 and 3-4. Basal lamella not visible in full-face view when mandibles fully closed.
Labrum terminates in a pair of elongate narrowly conical lobes that taper apically.
Clypeus with anterior margin narrowly convex, bluntly pointed apically; lateral margins strongly divergent posteriorly. Outer margins of mandibles visible outside lateral clypeal margins in full-face view.
Clypeal dorsum with broadly spatulate anteriorly curved hairs. Lateral clypeal margins with a fringe of broadly spatulate hairs that are strongly anteriorly curved.
Preocular carinae visible in full-face view, the frontal lobes and frontal carinae not expanded laterally.
Ventrolateral margin of head angulate but not sharply marginate between eye and base of mandible. Postbuccal impression broad and shallow but distinct.
Cuticle of side of head within the scrobe reticulate-punctate.
Scape of moderate length, SI 82-88, slender, only very slightly dorsoventrally compressed and without an acute flange-like leading edge.
Leading edge of scape with narrowly spatulate hairs, all of which are decumbent and strongly curved toward apex of the scape.
Propodeum with a pair of triangular teeth, subtended by lamellae.
Petiole with a large lateral spongiform lobe on the node, the ventral appendage present but only a narrow transparent strip. Postpetiole with moderate lateral spongiform lobes but the ventral lobes very large. Base of first gastral sternite with a diffuse fibrous spongiform pad.
Pilosity. Pronotal humeral hair long and flagellate.
Notes
This group contains another isolated species that has independently acquired long narrow mandibles. As is often the case elongation of the mandible blade has taken place between the basal lamella and basal tooth but in tanymastax there has been no reduction in the total number of teeth, nor have the teeth become more widely spaced on the margin. The result of this gives the appearance of a more or less normal dentition out on the end of a narrow mandible with an extraordinarily elongated basal diastema.
References
- Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.