Strumigenys rogeri-group

Bolton, B., 2000, The ant tribe Dacetini. With a revision of the Strumigenys species of the Malgasy Region by Brian L. Fisher, and a revision of the Austral epopostrumiform genera by Steven O. Shattuck., Memoirs of the American Entomological Institute 65, pp. 1-1028 : 656-657

rogeri-group

DIAGNOSIS OF WORKER

Apical fork of mandible with 2 spiniform teeth, without intercalary teeth or denticles.

Mandible with 1 or 2 stout preapical teeth which are situated in the apical third of the length; when 2 present then proximal slightly longer than distal. Mandible in full-face view almost straight and at full closure parallel (diverging apically in vazimba ). MI 43 - 66.

Scape elongate and more or less cylindrical. SI 62 - 112.

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 in the side of the head that extends towards the dorsal outline. Preocular notch extends onto the ventral surface of the head as a transverse preocular groove that runs toward 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 usually well developed into a ventral curtain, but occasionally very narrow or nearly absent. Postpetiole with lateral and ventral lobes. Lamella of propodeal declivity absent or very narrow.

Pilosity. Pronotal humeral hair either absent, or stiffly filiform, or rarely flagellate.

Cephalic dorsum with a transverse row of 4 - 6 hairs near occipital margin and 1 pair near vertex. Upper scrobe margin posteriorly with 2 - 4 (usually 3) stiff erect hairs that are longer than hairs on leading edge of scape. Mesonotum usually with 1 pair of erect hairs, occasionally with two pairs.

Sculpture. Head and alitrunk reticulate-punctate, occasionally with longitudinal or oblique rugulae or costulae; pleurae usually smooth, rarely punctate. Gaster unsculptured except for basigastral costulae.

Glands. Scape gland absent ( admixta , ection , labaris , luca , milae , nambao , rogeri , sphera , vazimba ) or visible as an elongate patch near apex of ventral or leading edge of scape ( carisa , fronto , hilaris , lysis , norax ). Femoral and tibial gland bullae entirely absent. Gland at base of calcar conspicuous. Tarsal gland bullae 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 usually set in a circular notch but less commonly in a concave impression ( carisa , hilaris ).

S. rogeri-group is immediately diagnosed by the following combination of characters: preocular and ventral preocular grooves present in head; scrobe and its dorsal margin extend posteriorly well beyond level of eye; mandible has 1 or 2 sharply defined acute preapical teeth or denticles. The group also contains 13 species in the Afrotropical region (see there).

Members of this group fall into 6 discrete complexes of related species in the Malagasy region, defined below. The first complex noted contains only rogeri , a cosmopolitan trampspecies discussed under the Afrotropical fauna, which is its region of origin. S. rogeri is easily isolated from other member of the group in Madagascar by its possesion of a flagellate pronotal humeral hair. It also has a characteristically shaped preocular notch. In profile, the width of the notch just in front of eye is narrow, distinctly less than the maximum diameter of the eye.

1 rogeri-complex ( rogeri ). Left and right mandible each with 2 preapical teeth, the proximal spiniform and longer than the distal. Pronotal humeral hair flagellate. Head tending to be somewhat shorter and narrower than in lysis- and hilariscomplexes, HL 0.59 - 0.61, HW 0.44 - 0.47.

2 lysis-complex ( lysis , nambao , norax ). Left and right mandible each with 2 preapical teeth, the proximal spiniform and longer than the distal. Pronotal humeral hair erect and stiffly filiform. HL 0.63 - 0.74, HW 0.47 - 0.60.

3 hilaris-complex ( hilaris , luca , milae ). Left and right mandible each with 2 preapical teeth, the proximal spiniform and longer than the distal. Pronotal humeral hair absent. HL 0.63 - 0.75, HW 0.52 - 0.61.

4 carisa-complex ( carisa , fronto ). Left and right mandible each with 1 preapical tooth or denticle. Pronotal numeral hair long and filiform, stiffly projecting. HL 0.80 - 1.00, HW 0.63 - 0.76.

5 sphera-complex ( admixta , ection , labaris , sphera ). Left and right mandible each with 1 preapical tooth or denticle. Pronotal humeral hair absent. Head shorter and narrower than in vazimba-complex, HL 0.64 - 1.06, HW 0.51 - 0.88.

6 vazimba-complex ( vazimba ). Left and right mandible each with 1 preapical tooth or denticle. Pronotal humeral hair absent. Head longer and broader than in all other complexes, HL 1.32 - 1.66, HW 1.28 - 1.65.