Strumigenys grandidieri group

Strumigenys grandidieri group Bolton (2000)

Species

Malagasy

Worker Diagnosis

Apical fork of mandible with 2-3 spiniform teeth, without intercalary teeth or denticles. Mandible with 0-2 stout preapical teeth, when present situated in the apical third of the length. Mandibles in full-face view and at full closure almost straight, parallel. MI 49-64.

Scape elongate and cylindrical. SI 77-132.

Upper scrobe margin ends, or at least becomes extremely indistinct, at about the level of the eye; without a row of hairs or fringed with a row of hairs which are the same shape and size as those on the cephalic dorsum.

Promesonotum flat to slightly convex dorsally and bluntly marginate laterally.

Ventrolateral margin of the head notched or indented immediately in front of the eye. With head in profile the preocular notch seen to continue vertically as a groove up the side of the head that extends towards the dorsal outline. Preocular notch also extends onto the ventral surface of the head as a transverse preocular groove that runs towards but does not reach the midline. An extremely deep and sharply defined post-buccal groove also present, extending across entire width of head immediately posterior of buccal cavity; post-buccal groove sharply separated from ventral preocular groove.

Spongiform appendages of petiole seg ments absent or weakly developed. Ventral spongiform lobes of postpetiole nearly absent or small but distinct.

Pilosity. Pronotal humeral hair usually absent but sometimes with a projecting stiff hair (Strumigenys dora, Strumigenys fanano). Upper scrobe margin without a row of hairs (Strumigenys actis, Strumigenys ampyx, Strumigenys bibiolona, Strumigenys chilo) or fringed by a continuous row of small curved hairs (Strumigenys dora, Strumigenys fanano, Strumigenys grandidieri). Cephalic dorsum with 4-6 standing hairs, usually with a transverse or of 4 near occipital margin. Mesonotum with at least 1 pair of erect hairs on anterior margin (none in bibiolona); entire body lacking flagellate hairs.

Sculpture. Head and alitrunk reticulate-punctate; middorsum of head and pronotal dorsum frequently with longitudinal or oblique rugulae in grandidieri. Petiole node and postpetiole disc in dorsal view reticulate-punctate. First gastral tergite unsculptured except for basigastral costulae or reticulate-punctate (dora, janano).

Glands. Scape gland visible as an elongate patch near apex of ventral or leading edge of scape. Femoral gland bullae decreasing in size from hind femur where it is easily visible to fore femur where it is minute to absent (bibiolona, chilo, grandidieri), or absent on all femora. Tibial gland bullae absent on all tibiae (dora), present only on hind tibia (actis, ampyx), or present on hind and fore tibiae (bibiolona, chilo, janano, grandidieri). Gland at base of calcar conspicuous. Tarsal gland bullae absent (dora) or visible on at least first three tarsi, decreasing in size from basitarsus where it is elongate to the third tarsal segment where it is oval. Mesopleural gland visible and set in a circular notch or concave impression.

Notes

The combined presence of a preocular notch in the ventrolateral margin of the head, a preocular impression on the ventral surface of the head, and an upper scrobe margin that ends, or at least becomes extremely indistinct, at about the level of the eye, is immediately diagnostic of the grandidieri-group.

The group contains 7 species, all of which are endemic in the Malagasy region; there are 3 complexes of related species.

chilo complex

Preapical teeth absent or at most a small spiniform denticle present immediately proximal of apicodorsal tooth on right mandible. Apical fork of mandible subtended by a third, shorter spiniform tooth. Upper scrobe margin without a row of hairs.

dora complex

Preapical teeth present, acute. Apical fork of mandible not subtended by a third spiniform tooth; at most the apicoventral tooth may have a minute spur or denticle at its ventral base. Upper scrobe margin fringed by a continuous row of small curved hairs. Pronotal humeral hair stiff. First gastral tergite and sternite densely punctate over the anterior half or more of the sclerite.

Strumigenys dora
Strumigenys fanano

grandidieri complex

Preapical teeth present, truncated. Apical fork of mandible not subtended by a third spiniform tooth; at most the apicoventral tooth may have a minute spur or denticle at its ventral base. Upper scrobe margin fringed by a continuous row of small curved hairs. Pronotal humeral hair absent. Gaster un sculptured except for basigastral costulae.

Strumigenys grandidieri

References

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