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Strumigenys paradoxa group
Strumigenys paradoxa group Bolton (2000)
Species
Neotropical
Worker Diagnosis
Mandibles in full-face view and at full closure stoutly triangular, outer margins convex, masticatory margins serially dentate and the teeth engage throughout the visible length. In profile dorsal margin of mandible with apical half strongly down-curved, the curvature commencing in front of the clypeal margin and approximately the apical third of the dorsal margin roughly at a right-angle to the long axis of the head. In ventral view outer margin of mandible without an inflected prebasal angle. MI 16.
Dentition. Basal lamella followed without a diastema by 5 stout triangular teeth, the teeth increasing gradually in size from 1 (basal) to 3, then 4 and 5 each slightly smaller.
Distal of tooth 5 with a row of about 5-6 denticles and a small apical tooth, giving a total dental count of 11 or 12.
Basal lamella of mandible not visible when mandibles fully closed. Apparently the lamella is a low rounded lobe that is not as tall as the basal tooth (left mandible of holotype slightly ajar).
Labrum terminates in a pair of tapering bluntly triangular lobes.
Clypeus with anterior margin broadly shallowly convex, the lateral margins feebly divergent posteriorly. In full-face view outer margins of mandibles pass just outside the anterolateral clypeal angles.
Clypeal dorsum with minute appressed simple hairs. Lateral clypeal margins with a few minute appressed hairs, without a fringe of freely projecting hairs.
Preocular carina clearly visible in full-face view.
Ventrolateral margin of head bluntly angulate in front of eye, not sharply marginate, weakly convex at the level of the postbuccal impression; the latter narrow and shallow.
Cuticle of side of head within antennal scrobe weakly reticulate, the upper half glossy but not completely devoid of reticulation, the lower half more strongly sculptured but not densely reticulate-punctate.
Scape short and stout, SI 53, increasing markedly in thickness from base to apex and not dorsoventrally flattened; leading edge rounded and blunt between dorsal and ventral surfaces.
Leading edge of scape with minute simple hairs that are slightly elevated from the surface and inclined toward the apex of the scape.
Mesopleural gland relatively large, in profile its maximum diameter almost vertical and about equal to the length of the anterior free margin of the katepisternum.
Metapleural gland bulla large, in profile its dorsal most point abutting the annulus of the propodeal spiracle.
Propodeum without teeth but the declivity with a narrow shallowly convex lamella that extends from just above the level of the spiracle to the base.
Spongiform appendages of petiole and postpetiole fully developed. Base of first gastral sternite in profile with a massive spongiform mass basally, much larger than is usual on this sclerite.
Pilosity. Pronotal humeral hair elongate and simple, fine and approximately straight, tape ring to an acute apex. Apicoscrobal hair long and simple, directed dorsolaterally, approximately straight, acute apically. Dorsal (outer) surfaces of middle and hind tibiae with numerous stout suberect simple hairs projecting freely from the surface, the longest of them only slightly shorter than the maximum width of the segment from which they arise.
Notes
A single small glossy species from Costa Rica, Strumigenys paradoxa, is currently placed in this group. At first glance, and as indicated in the above description, it seems very distinct from all other members of the genus, but a more detailed look suggests close relationship with the long-mandibulate Strumigenys warditeras, also from Costa Rica. Despite the very different mandibular structures of paradoxa and warditeras overall similarities are otherwise striking, and leaving out obvious autapomorphies a number of interesting synapomorphies are exhibited by the two.
1 Metapleural gland bulla is hypertrophied.
2 Basal spongiform pad on first gastral sternite is enormous.
3 First gastral sternite is concave.
4 Alitrunk sculpture is lost.
5 Propodeal declivity in profile commences well above the point of origin of the lamella.
6 Postpetiole is the same shape.
7 Basigastral costulae are the same in form and extent.
8 Eyes are very reduced.
The many obvious differences between the two groups, adequately demonstrated by comparing their diagnoses, confirms that they must be placed in separate groups, but their synapomorphies indicate that the two groups are certainly sisters.
References
- Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.