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Strumigenys warditeras group
Strumigenys warditeras group Bolton (2000)
Species
Neotropical
Worker Diagnosis
Mandibles in full-face view and at full closure elongate and sublinear, far apart on the anterior clypeal margin, gradually tapering from base to apex and engaging only at their extreme apices where there is a vertical row of teeth and denticles. Outer margins of mandibles shallowly convex, inner margins widely separated and enclosing a broad space that extends the entire mandible length. Labral lobes visible basally between the mandibles. In profile mandible broad at apex; upper and lower margins more or less parallel to the articulation, the dorsal margin not angled downward at level of anterior clypeal margin. In ventral view outer margin without a suddenly inflected prebasal angle. MI 35.
Dentition. A single small preapical denticle present, sloped anteriorly and located close to the apex. Apically the mandible equipped with a vertical series of teeth and denticles. Apicodorsal tooth by far the stoutest and longest, extensively crossing over its counterpart from the opposing mandible at full closure. Below this are two small teeth, a somewhat larger tooth, an indistinct series of 10-12 minute denticles and an apicoventral small tooth.
Basal lamella not visible in full-face view when mandibles fully closed (thus in only known specimen); in frontal view anterior margin of small lamella visible, overlapping outer margin of labrum below the clypeus.
Labrum terminates in a pair of short, broadly triangular lobes.
Clypeus with anterior margin transverse, the lateral margins approximately straight and shallowly divergent posteriorly. In full-face view the anterolateral clypeal angles are at about the midwidths of the mandibles; outer margin of mandible basally is outside the lateral clypeal margin to its extreme base.
Clypeal dorsum with minute appressed pilosity; lateral and anterior clypeal margins without projecting hairs.
Preocular carina visible through its entire length in full-face view; frontal lobes narrow, frontal carinae divergent posteriorly but not at all expanded laterally.
Scrobe absent; side of head behind antennal insertion with a shallowly depressed area that terminates at the eye. In full-face view frontal carinae diverge widely posteriorly from the frontal lobes and terminate at the eyes, the latter visible in this view; lateral margins of occipital lobes commence immediately behind eyes.
Ventrolateral margin of head rounded immediately in front of eyes, bluntly marginate below level of preocular carina. Postbuccal impression shallow and narrow.
Cuticle of side of head finely reticulate-punctate within a triangle formed by the frontal lobe, eye and mandibular insertion.
Scape short, SI 60, very stout in dorsal view, increasing in width from base to apex and without a strongly defined subbasal angle. Scape extremely weakly dorsoventrally flattened distal of the down curved basal section.
Leading edge of scape hairless.
Middle and hind legs with femoral gland bullae expanded into long narrow pale streaks that extend from the basal quarter almost to the apex of each femur. Tibial gland bullae also conspicuous on all legs.
Metapleural gland bulla large, extending up the side almost to the spiracle; diameter of spiracle greater than distance that separates its margin from the apex of the bulla.
Propodeum with a pair of low-set triangular teeth that are subtended by, and mostly fused with, the lamellae of the declivity.
Spongiform appendages present on petiole and postpetiole. Base of first gastral sternite in profile with a very large deep spongiform pad.
Pilosity. Pronotal humeral hair absent. Dorsal surfaces of head and body without any standing hairs and without specialised appressed hairs; only sparse minute appressed pubescence is present. Dorsal (outer) surfaces of tibiae with minute appressed pubescence only.
Notes
A single spectacularly strange Costa Rican species, Strumigenys warditeras, occupies this group; its diagnosis renders it immediately recognisable.
The long mandibles with vertical series of teeth at the apex have a structure reminiscent of some members of the argiola group. However, no other diagnostic characters correspond, and it is clear that the mandible structure has been acquired convergently. The elongate streak-like femoral gland bullae and suppression of the scrobe are apomorphic in warditeras and not seen anywhere else in the genus. The enlarged metapleural gland, and several other features are similarly developed in Strumigenys paradoxa, another Costa Rican species which may well be the closest living relative of warditeras, as discussed under paradoxa.
References
- Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.