Strumigenys capitata group

Every Ant Tells a Story - And Scientists Explain Their Stories Here
Jump to navigation Jump to search

Strumigenys capitata group Bolton (2000)

Species

Malesian-Oriental-East Palaeartic

Strumigenys karawajewi also occurs in the Austral region.

Worker Diagnosis

Mandibles in full-face view and at full closure triangular to elongate triangular, with serially dentate masticatory margins that engage through most or all of their length; at most the extreme basalmost teeth just fail to engage. In ventral view outer margin of mandible without an inflected prebasal angle. MI 19-36.

Dentition. Basally with a row of 5 or 7 teeth; three conspicuous teeth follow the basal lamella; counting from the base the third tooth is the longest, the fourth tooth is shorter than the third and usually also shorter than the fifth. Preapical tooth not a minute denticle but enlarged and almost as large as the apical. Total dental count 12 (except in Strumigenys serraformis and Strumigenys serradens where a secondary increase in denticle count to about 25 has occurred).

Basal lamella of mandible usually a low, broad lobe, but may be elongate in some species, shorter and roughly triangular in others. Outline of lamella convex to flattened, usually about equal in height to the two basal most teeth, which follow it without a diastema; lamella concealed or partially to entirely visible in full-face view with the mandibles fully closed.

Labrum terminates in a pair of narrow lobes that may be triangular, digitate or conical.

Clypeus with anterior margin convex, usually broadly and evenly so, but more narrowly rounded anteromedially in some species. Lateral margins of clypeus short, more or less straight to weakly convex, rounding evenly into the anterior margin.

Clypeal dorsum with anteriorly directed short spatulate hairs that are decumbent to appressed. Anterior and lateral margins of clypeus in full-face view with a continuous fringe of elongate spatulate to weakly spoon-shaped hairs that project freely beyond the outline of the clypeus and are curved anteriorly or anteromedially.

Preocular carina broad, conspicuous in full-face view.

Ventrolateral margin of head between eye and mandible forming a blunt angle between side and ventre. Postbuccal impression shallow and inconspicuous.

Cuticle of side of head within scrobe reticulate to densely reticulate-punctate.

Scape very short to moderate, SI 46-78, weakly to distinctly dorsoventrally flattened but not m assively broadened in dorsal view, the dorsum and ventre converging anteriorly; leading edge blunt to sharp, sometimes in the form of a thin crest; subbasal bend shallow to pronounced.

Leading edge of scape with a row of curved remiform, spatulate or spoon-shaped projecting hairs. One to four of these hairs conspicuously curved toward the base of the scape.

Pronotum not marginate dorsolaterally, the dorsum with a variably developed median carina; absent in some species, present on anterior third in others, complete in several species.

Promesonotum in profile forming a high convexity, often domed; mesonotum sloping strongly posteriorly to the metanotal groove; the latter weakly to strongly impressed.

Propodeum bidentate to short bispinose, lamella on declivity frequently vestigial or in the form of a narrow carina; moderately broad in a few species but never engaging the entire length of the spine or tooth.

Spongiform appendages of waist segments present, varying in size between species. Base of first gastral sternite in profile with a distinct pad of dense spongiform tissue; in some species the spongiform tissue extends posteriorly along the midline of the sternite.

Pilosity. Pronotal humeral hair present, may be claviform, remiform, filiform or flagellate and may arise directly from the surface or from the apex of a small papilla. Apicoscrobal hair present, either remiform, clavate, filiform or flagellate. In profile the dorsum of the head close to the occipital margin with a transverse row of 4 (rarely 6) elongate, anteriorly curved standing hairs that are distinctly differentiated from any other cephalic pilosity that may be present. Usually (but not always) an additional pair or row of standing longer hairs projects from the dorsum just in front of the highest point of the vertex. Mesonotum with 1-3 pairs of long suberect to erect stout hairs. Dorsal (outer) surfaces of middle and hind tibiae and basitarsi with short, apically curved narrowly spatulate hairs that are subdecumbent to appressed.

Sculpture. Dorsum of head behind clypeus reticulate-punctate. Alitrunk often entirely finely densely reticulate-punctate, or with part or all of pleurae smooth.

Notes

Members of the capitata-group are widely distributed in the Malesian region, covering the whole of Malaysia, Indonesia to New Guinea, the Philippines, and extending out into the island systems of the Pacific Ocean. One species, Strumigenys dohertyi, occurs in the extreme south of the Oriental region, being found in southern China, Burma and Thailand, but the group is apparently absent from the Indian subcontinent and the remainder of the Oriental region. The group has no representatives in the East Palaearctic region but one widely distributed species (Strumigenys karawajewi) has been found in Queensland, Australia. Species of this group are generally the most commonly encountered members of Pyramica within this area. Only the isolated species Strumigenys mitis, from outside the group, occurs in similar numbers and over approximately the same range.

References

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