Strumigenys rogeri group

rogeri species group

Bolton, Barry. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65: 1-1028.


 * Strumigenys bernardi
 * Strumigenys cacaoensis
 * Strumigenys dromoshaula
 * Strumigenys faurei
 * Strumigenys londianensis
 * Strumigenys petiolata
 * Strumigenys pretoriae
 * Strumigenys rogeri
 * Strumigenys rufobrunea
 * Strumigenys sarissa
 * Strumigenys shaula
 * Strumigenys transenna
 * Strumigenys vazerka

DIAGNOSIS OF WORKER

Apical fork of mandible usually without intercalary teeth; more rarely one or both with an intercalary denticle (in one species left fork with two dentic1es). Right mandible with two preapical teeth, the proximal spiniform and longer than the distal (latter may be very small and concealed by opposing apicodorsal tooth at full closure) ; left mandible similar or with distal preapical tooth lost. MI 40 - 65.

Scape subcylindrical to very weakly dorsoventrally flattened, short to long, SI 62 - 97.

Ventrolateral margin of head with a deep, strongly incised preocular notch; notch so strongly incised that in dorsal view anterior portion of eye is detached from side of head. With head in ventral view the preocular notch forms the apex of a transverse impression or trench in the ventral surface of the head capsule that extends toward the midline. This ventral preocular groove is posterior to, and separated from, the marked postbuccal groove. Side of head immediately above preocular notch usually with a vertical impression.

Ventral surface of petiole usually with a conspicuous spongiform strip or curtain; spongiform lobes of postpetiole present but first gastral sternite without a basal spongiform pad.

Pilosity. Pronotal humeral hair absent or present. Apicoscrobal hair absent; upper scrobe margin fringed by a continuous row of small curved hairs. Cephalic dorsum with 0 - 6 standing hairs, usually with a transverse row of 4 near occipital margin and a pair close to highest point of vertex; variously reduced in some complexes and individual species. Mesonotum with a single pair of standing hairs. First gastral tergite with simple to remiform hairs; flagellate hairs always absent.

Sculpture. Head and alitrunk reticulate-punctate; pronotal dorsum frequently with longitudinal or oblique rugulae or costulae; pleurae and side of propodeum usually smooth, rarely punctate. Gaster unsculptured except for basigastral costulae.

Members of the rogeri-group are instantly diagnosed by the presence of a deep preocular notch in the ventrolateral margin of the head that detaches the anterior portion of the eye from the side of the head. In ventral view the preocular notch is seen as the apex of a transverse groove or impression that extends across the ventral surface toward, but not reaching, the ventral midline. This preocular transverse groove is posterior to, and separated from, the postbuccal transverse groove. The latter is immediately posterior to the buccal cavity and is universally present in Afrotropical species. In profile the preocular notch is often also the base of a vertical groove that ascends the side of the head immediately in front of the eye; in some species this vertical groove interrupts the dorsolateral margin of the head.

The group contains 13 species in the Afrotropical region and is also well represented in Madagascar (see there) where an extensive radiation has taken place. In the Afrotropical fauna five complexes of closely related species can be recognised.

1 londianensis-complex (Strumigenys londianensis, Strumigenys sarissa, Strumigenys transenna). Left mandible with 1 spiniform preapical tooth (the proximal); right mandible with 2 preapical teeth but the distal very small and usually concealed by the opposing apicodorsal tooth at full closure. Apical fork of left mandible with 1 intercalary denticle or small tooth; apical fork of right mandible without intercalaries. Cephalic dorsum without standing hairs or at most with 1 pair present close to occipital margin. Scape relatively long, SI 82 – 97.

2 cacaoensis-complex (Strumigenys cacaoensis). Left and right mandibles each with 2 small preapical teeth, these either about the same size or the proximal slightly shorter than the distal. Apical fork of left mandible with 2 intercalaries, the upper a sharp tooth and the lower a denticle; apical fork of right mandible with 1 minute intercalary denticle. Cephalic dorsum without standing hairs. Mesopleuron, metapleuron and side of Propodeum reticulate-punctate. Head relatively broad and scape short, CI 86 - 91, SI 62 –67. Arboreal.

3 rogeri-complex (Strumigenys bernardi, Strumigenys rogeri, Strumigenys vazerka). Left and right mandibles each with 2 preapical teeth, the proximal spiniform and longer than the distal (for exceptions see under bernardi); preapical teeth not crowded together near apical fork. Apical fork on each mandible without intercalary teeth or denticles. Cephalic dorsum with a transverse row of 4 erect short hairs close to occipital margin and with similar pair close to highest point of vertex. Scapes and mandibles relatively long, SI 79 – 92, MI 50 –65; head tending to be somewhat longer and narrower than in following two complexes, CI 65 – 75.

4 pretoriae-complex (Strumigenys dromoshaula, Strumigenys pretoriae, Strumigenys shaula). Left and right mandibles each with 2 apical teeth, the proximal spiniform and longer than the distal; preapical teeth crowded together near apical fork. Apical fork on each mandible without intercalary teeth or denticles. Cephalic dorsum either with a transverse row of 4 erect short hairs close to occipital margin or with this row and a pair close to highest point of vertiex. Eyes large, maximum diameter 0.18 – 0.24 X HW. Scapes and mandibles relatively short, SI 64 – 77, MI 44 – 49; head tending to be shorter and broader than in rogeri-complex, CI 71 – 81.

5 rufobrunea-complex (Strumigenys faurei, Strumigenys petiolata, Strumigenys rufobrunea). Left and right mandibles each with 2 preapical teeth, the proximal spiniform and longer than the distal; preapical teeth not crowded together near apical fork. Apical fork on each mandible without intercalary teeth or denticles. Cephalic dorsum with a transverse row of 4 erect short hairs close to occipital margin and with similar pair close to highest point of vertex. Maximum diameter of eye about 0.15 X HW or less. Scapes and mandibles relatively short, SI 64 – 74, MI 44 – 50; head tending to be shorter and broader than in rogeri-complex, CI 73 – 83.