Strumigenys splendens group

Strumigenys splendens group Bolton (2000)

Species

Neotropical

• Strumigenys abditivata
• Strumigenys comis
• Strumigenys dentinasis
• Strumigenys inusitata
• Strumigenys kompsomala
• Strumigenys moloch
• Strumigenys rugithorax
• Strumigenys splendens
• Strumigenys villiersi

Worker Diagnosis

Mandibles in full-face view and at full closure narrowly triangular and slender, dentate margins fully engage; sometimes much of length concealed by the anterior clypeal margin. Dental row occupies distal half to entire exposed length, the teeth small. In ventral view outer margin of mandible without a prebasal inflected angle. MI 3-24.

Dentition. Basal lamella is followed immediately by 4 or 5 small teeth that are narrowly triangular to spiniform. Distal of these are 5-8 even smaller teeth or denticles and a larger apical tooth, giving a total dental count of 12-14.

Basal lamella elongate and low, roughly rectangular, usually visible or partially visible when mandibles fully closed and at least as long as the tooth-row in full-face view when mandibles are open (not in Strumigenys moloch, Strumigenys inusitata, see below).

Labrum terminates in a pair of narrow triangular to digitate lobes.

Clypeus with anterior margin narrowly convex in full-face view; lateral margins divergent posteriorly. In ventral view the lateral clypeal margins either do not project beyond the outer margins of the mandibles, or project only at the extreme mandibular bases (except in inusitata, see below).

Clypeal dorsum hairless or at most with minute appressed pubescence. Anterior and lateral margins without projecting hairs, without a continuous fringe of specialised hairs though 2 - 3 may be present posterolaterally (1 species).

Preocular carina varying from visible to completely concealed in full-face view.

Ventrolateral margin of head sharply marginate in front of eye, the margination straight to shallowly concave, never abruptly and narrowly arched adjacent to the postbuccal impression; sometimes terminating anteriorly in an angle or small tooth. Postbuccal impression conspicuous to very shallow.

Cuticle of side of head within the scrobe smooth and shining.

Scape very short to moderate, SI 45-80, slender and subcylindrical, angular or slightly dorsoventrally flattened, without a sharp flange-like leading edge; the latter almost straight or only very weakly convex.

Leading edge of scape hairless or at most with a few short elevated hairs or minute appressed hairs present that are all directed toward the apex of the scape.

Propodeum armed with a pair of acute teeth or spines that are subtended by lamellae or carinae.

Petiole node in dorsal view longer than broad. In profile height of the anterior face of the node less than the length of the dorsum of the node.

Spongiform appendages of waist segments usually fully developed; some lobes may be relatively small in some species (ventral lobe of postpetiole lost in two species).

Base of first gastral sternite in profile with a spongiform pad (lost in one species).

Sculpture. Dorsum of head behind clypeus smooth to irregularly granulate, rarely closely punctate but not finely densely reticulate-punctate everywhere. Frontal carinae dorsally mostly or entirely finely densely sculptured, even when vertex otherwise smooth. Sides of alitrunk and disc of postpetiole smooth.

Pilosity. Pronotal humeral hair present or absent.

Notes

The previously described species discussed here were originally members of the genus Gymnomyrmex, now abandoned (Bolton, 1999).

The mandibular basal lamella in the very specialised moloch is a much reduced form of, though obviously derived from, the condition described above. It takes the form of an extremely narrow cuticular rim that terminates distally in a minute lobe at about the midpoint of the exposed mandible length at full closure. The tiny lobe is smaller than the basal tooth that it immediately precedes. In effect the lamella has fallen out, so that there is a gap between the basal halves of the inner mandibular margins at full closure, through which part of the labrum is visible, and each mandible in full-face view is effectively diastemate from about its midlength to the level of the anterior clypeal margin.

In inusitata the clypeus is enormously modified, overhanging and concealing the mandibles almost totally so that their dentition and basal lamellae are concealed; see under description of the species.

References

• Bolton, B. 1999. Ant genera of the tribe Dacetonini (Hymenoptera: Formicidae). Journal of Natural History. 33:1639-1689.
• Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028.