Strumigenys datissa

Identification
Bolton (2000) - A member of the truncatidens complex in the Strumigenys emarginata  group. Characters of truncatidens-complex. In full-face view dorsolateral margin of head behind level of apex of scrobe without laterally projecting hairs. Mesonotum without standing hairs. Disc of postpetiole sharply longitudinally costulate. Head and alitrunk dark brown to blackish brown.

Bolton (1983) - The truncatidens-complex of this group contains five species. Four of these, Strumigenys gatuda, Strumigenys hensekta, Strumigenys dendexa (= truncatidens) and Strumigenys truncatidens, possess conspicuously projecting hairs on the sides of the occipital lobes. In datissa, however, such projecting hairs are absent, any hairs which occur on the sides of the occipital lobes being small and curved, usually closely adherent to the head and not freely projecting. S. datissa is also separated from gatuda, dendexa and hensekta by having the postpetiolar disc longitudinally costulate; it is glassy smooth in the last three named. A few specimens of truncatidens do show costulae either on part or all of the postpetiole but here the mesonotum has a pair of long erect hairs which are not seen in datissa.

Distribution based on Regional Taxon Lists
Afrotropical Region: Rwanda.

Nomenclature

 *  datissa. Smithistruma datissa Bolton, 1983: 289, fig. 9 (w.) RWANDA. Combination in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 118. See also: Bolton, 2000: 301.

Worker
Holotype. TL 2.7, HL 0.70, HW 0.54, CI 77, ML 0.12, MI 17, SL 0.34, SI 63, PW 0.34, AL 0.74.

Mandibles armed with 5 relatively large teeth following the basal lamella (which is concealed by the clypeus in the holotype). Distal to the 5 principal teeth are 2 slightly smaller teeth, a row of four denticles and a small apical tooth. Anterior clypeal margin broadly and evenly concave between the anterolateral corners, the margin equipped with 10 scale-like hairs which project forward over the mandibles. These hairs become gradually larger away from the midline but the outermost, at the anterolateral corner, is much the largest and forms an intermediate between the shorter hairs on the anterior margin and the large spatulate to spoon-shaped anteriorly curved hairs which form a fringe on the lateral clypeal margins. In full-face view the preocular laminae slightly divergent anteriorly. Clypeal dorsum more or less smooth centrally but feebly sculptured laterally and anteriorly. Cephalic dorsum densely shallowly reticulate-punctate everywhere. Dorsum of head with numerous small, widely spaced flattened hairs which are subdecumbent to decumbent and are mostly directed anteriorly. In full-face view the sides of the head with a few such hairs projecting, curved anteriorly, most conspicuous on the sides of the occipital lobes. Flagellate hairs absent. Antennal scapes narrow basally, shallowly bent at about the basal third and broadest at this point. The leading edges of the scapes evenly curved at the bend and equipped with a row of projecting spatulate to broadly clavate hairs and an interspersed row of shorter much finer simple hairs. Maximum diameter of eye about O·13xHW, approximately equal to the maximum width of the scape. Head in profile roughly wedge-shaped, the vertex forming a high narrowly rounded convexity, the ventral surface evenly shallowly convex. Pronotal dorsum without a median longitudinal ridge or carina, not sharply marginate laterally. Alitrunk without flagellate hairs. With the alitrunk in profile the posterior part of the pronotum and anteriormost section of the mesonotum raised into a broad shallowly convex tumulus, the remainder of the mesonotum and the propodeum, which form a single surface without trace of a metanotal groove, markedly depressed below the level of this tumulus. Propodeal teeth short and broadly triangular, the infradental lamellae narrow but clearly visible. Dorsal alitrunk with scattered short flattened hairs which are decumbent to appressed, without standing pilosity of any description. Petiole and postpetiole dorsally with similar but extremely sparse hairs, the latter also with 4 clavate suberect hairs projecting from the posterior margin. In the holotype a single clavate hair is also present on the left side of the postpetiolar disc, appressed to the surface; this is not matched in the paratypes. First gastral tergite with numerous suberect to erect stout hairs which are simple to weakly clavate apically. Pronotal dorsum predominantly broadly reticulate-punctate but anteriorly and laterally the margins of the punctures tending to run together and form very fine rugulae. Mesonotum and propodeal dorsum more sharply punctate, the sculpture on the latter running between the propodeal teeth and ending about half way down the declivity. Petiole dorsum minutely rugulose, the disc of the postpetiole finely longitudinally costulate. Basigastral costulae sharply developed and conspicuous, the tergite otherwise unsculptured. Alitrunk pleurae mostly smooth centrally but punctulate marginally, a line of punctures separating meso- and metapleuron and a relatively densely punctured patch on the mesopleuron behind the upper half of the front coxa. Spongiform appendages of pedicel segments moderately large in profile. In dorsal view the petiole node with a posterior spongiform strip which is continued down the sides. Postpetiole with a narrow spongiform strip anteriorly and a broader strip bordering the posterior margin which is slightly narrowed medially. Colour dark brown.

Paratypes. TL 2.6-2.7, HL 0.70, HW 0.54, CI 77, ML 0.12, MI 17, SL 0.34, SI 63, PW 0.32-0.34, AL 0.73-0.74 (2 measured).

As holotype but maximum diameter of eye 0.13-0.15 X HW.

Type Material
Holotype worker, Rwanda: Rangiro, ix.1976 (P. Werner). Paratypes. 2 workers with same data as holotype.