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Strumigenys lygatrix group
Strumigenys lygatrix group Bolton (2000)
Species
Neotropical
Worker Diagnosis
Mandibles in full-face view and at full closure subtriangular, outer margins convex and the masticatory margins engage throughout their length. In profile apical third or so of dorsal margin abruptly angled downward. In ventral view outer margin of mandible evenly curved, without an inflected prebasal angle. MI 20.
Dentition. Difficult to discern in holotype (only known specimen). Basal tooth follows basal lamella without a diastema. Apparently with 5 larger teeth basally, followed by an indeterminate series of denticles and terminating in an enlarged apical tooth which appears to be the largest on the entire margin.
Basal lamella of mandible large, elongate-subrectangular and glossy, extensively visible in full-face view with mandibles fully closed and about as tall as the basal series of teeth; a minute V-shaped space present between lamellar inner margins immediately in front of the midpoint of the clypeus.
Labrum terminates in a pair of narrowly digitate lobes that are weakly convergent anteriorly.
Clypeus with anterior margin transverse, the lateral margins short, approximately straight and slightly divergent posteriorly. Outer margins of fully closed mandibles pass just outside the anterolateral clypeal angles in full-face view. In ventral view the lateral clypeal margins are not visible, or only just visible, beyond the line of the outer mandibular margins.
Clypeal dorsum with numerous short fine simple decumbent hairs that are directed anteriorly. Lateral clypeal margins in full-face view with decumbent to appressed anteriorly directed short simple hairs; without freely projecting or bizarre pilosity.
Frontal lobes and anterior portions of frontal carinae strongly expanded laterally, the expanded area ending abruptly at about the level of the posterior margin of the eye; margin of frontal lobe anteriorly making an obtuse angle with the posterolateral border of the clypeus.
Preocular carina visible anteriorly in full-face view.
Eye large, its outer margin convex and clearly visible in full-face view, distinctly projecting beyond the outline of the dorsolateral margin.
Ventrolateral margin of head rounded to bluntly angulate between eye and mandible, very shallowly concave at level of the small postbuccal impression, without a marked narrow concave arch whose apex approaches the level of the top of the eye.
Cuticle within scrobe mostly smooth and shining ; a narrow punctulate strip extends longitudinally in front of the eye and behind the eye the punctulate strip curves upward along the posterior margin of the scrobe.
Scape short, SI 57, its margins weakly sinuate and without a pronounced subbasal angle.
Scape not dorsoventrally flattened, its maximum depth in anterior view equal to its maximum width in dorsal view.
Leading edge of scape with a row of suberect short simple hairs that are inclined or shallowly curved toward the apex of the scape; the longest of these hairs is distinctly shorter than half the maximum scape width.
Pronotum weakly marginate dorsolaterally, the mesonotum and propodeum more sharply marginate.
Propodeum armed with a pair of triangular teeth, subtended by narrow lamellae.
Spongiform appendages of waist segments fully developed; petiole with a ventral curtain and lateral lobes; postpetiole with large ventral and aliform lateral lobe; base of first gastral sternite with a diffuse but distinct pad of spongiform tissue.
Pilosity. Pronotal humeral hair present, fine curved and simple.
Notes
A single species currently occupies this group, lygatrix, from Argentina. It is very much an isolated species, without obvious close relatives. The structure of the head is similar to that seen in the thaxteri group but the numerous differences between the two groups are apparent by comparing their diagnoses.
References
- Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.