Strumigenys hastyla

Known from rainforest and swamp forest, samples have been collected from the lltter, in rotten logs and under bark.

Identification
Bolton (2000) - A member of the Strumigenys scotti-group. Outer margin of mandible evenly shallowly curved. Eye with ca 15 ommatidia in total; maximum diameter of eye greater than maximum width of slender scape. Preocular notch absent. Hairs that fringe upper scrobe margin somewhat longer than those on leading edge of scape but both series small and narrow. Petiole node in dorsal view broader than long. Hairs on first gastral tergite thickened or flattened apically.

Bolton (1983) - Variation in this non-paratypic material is as follows. TL 2.0-2.1, HL 0.48-0.54, HW 0. 34-0.39, CI 70-74, ML 0.21-0.24, MI 42-46, SL 0.27-0.31, SI 76-82, PW 0.22-0.25, AL 0.48-0.56 (18 measured). The pronotum in some is wholly reticulate-punctate dorsally, the fine longitudinal rugulae seen in the type-series being suppressed. Much of the West African material is darker in colour, medium brown, so that the cephalic ground-pilosity is more conspicuous.

S. hastyla is one of three very closely related species. Along with Strumigenys scotti and Strumigenys zandala, Strumigenys hastyla is characterized by the form of the mandibles, the elongate almost cylindrical scapes, the relatively slender fringing hairs on the upper scrobe margins (which are only slightly or not at all larger than the cephalic ground-pilosity), the large eyes, lack of a preocular notch and ventral preocular groove or impression, and evenly rounded sides of the head which round into the upper scrobe margins without trace of an angle. These three species are very similar and difficult to separate. S. scotti is the largest of the three and has relatively long mandibles and scapes; it also tends to have the petiole node longer than broad in dorsal view whereas in the other two the node is very obviously broader than long.

S. hastyla is the smallest species of the three in absolute terms. It also differs from zandala as the gastral hairs are simple in the latter but mostly flattened or thickened apically in hastyla.

Distribution based on Regional Taxon Lists
Afrotropical Region: Angola, Burundi, Cameroun, Central African Republic, Gabon, Ivory Coast, Nigeria, Uganda.

Nomenclature

 *  hastyla. Strumigenys hastyla Bolton, 1983: 372 (w.) BURUNDI. See also: Bolton, 2000: 609.

Worker
Holotype. TL 2.0, HL 1.52, HW 0.38, CI 73, ML 0.23, MI 44, SL 0.29, SI 76, PW 0.24, AL 0.52.

Mandibles slender in full-face view, the outer margins evenly and very shallowly curved, the blades only slightly tapering from their broadest point near the base to the apex. Apical fork of each mandible with 2 spiniform teeth, without intercalary teeth or denticles. Each mandible with 2 preapical teeth which are stout and situated within the apical quarter of the length of the blade, the proximal tooth slightly longer and thicker than the distal. The preapical teeth on each blade close together so that the length of the distal tooth is more than twice the distance which separates their bases. Upper scrobe margins shallowly divergent and evenly curved, confluent with the sides of the occipital lobes through an even smooth curve in full-face view. Eyes quite large, with about 15 ommatidia, the maximum diameter of the eye distinctly greater than the maximum width of the scape. Preocular notch absent, the ventral surface of the head without a preocular transverse groove or impression on each side. Antennal scapes slender and almost cylindrical, very shallowly curved in the basal third, their leading edges with a row of apically curved slender hairs which are somewhat flattened to very feebly and narrowly spoon-shaped, smaller than the hairs fringing the upper scrobe margins. Cephalic ground-pilosity of numerous narrowly spatulate to slender spoon-shaped hairs, the upper scrobe margins fringed with a row of similar or very slightly larger hairs. Dorsum of head with 6 standing hairs, arranged in a transverse row of 4 close to the occipital margin and a more anteriorly situated pair. Dorsum of head reticulate-punctate. Pronotal humeri each with a single fine flagellate hair. Mesonotum with a single pair of standing hairs. Ground-pilosity of dorsal alitrunk like that of head but the hairs smaller and more widely scattered. Mesonotum shallowly depressed behind the level of the pair of hairs. Propodeal teeth triangular and subtended by conspicuous infradental lamellae. Sides of pronotum weakly rugulose. Pleurae and sides of propodeum mostly smooth but with punctate areas around the periphery. Pronotum dorsally finely longitudinally rugulose, the spaces between the rugulae superficially punctate. Remainder of dorsal allitrunk reticulate-punctate. Dorsum of petiole node reticulate-punctate, the propodeum smooth. Spongiform appendages of pedicel segments well developed, the petiole with a broad ventral strip and a distinct lateral lobe on the node, the postpetiole with large ventral and lateral spongiform lobes. In dorsal view the disc of the postpetiole appears surrounded by spongiform tissue on all sides as the lateral and ventral lobes project beyond the outline of the disc. Basigastral costulae arise on the first tergite on each side of a central clear area. Dorsal surfaces of petiole, postpetiole and gaster with standing hairs, some or all of which are thickened or flattened apically in dorsal view. Colour brownish yellow.

Paratypes. TL 1.8-2.0, HL 0.49-0.52, HW 0.36-0.38, CI 73-75, ML 0.22-0.23, MI 43-45, SL 0.28-0.29, SI 76-78, PW 0.22-0.24, AL 0.48-0.52 (3 measured). As holotype.

Bolton (2000) - TL 1.8-2.1, HL 0.48-0.54, HW 0.34-0.39, CI 70-75, ML 0.21-0.24, MI 42-46, SL 0.27-0.31, SI 76-82, PW 0.22-0.25, AL 0.48-0.56 (22 measured).

Type Material
Holotype worker, Burundi: Bujumbura, 1977, no. 17 (A. Dejean). Paratypes. 3 workers with same data as holotype (BMNH; ).

References based on Global Ant Biodiversity Informatics

 * Bolton B. 1983. The Afrotropical dacetine ants (Formicidae). Bulletin of the British Museum (Natural History). Entomology 46: 267-416.
 * Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
 * IZIKO South Africa Museum Collection