Strumigenys serraformis

Known from the type series, a collection taken from a rotten log in a wet forest.

Identification
Bolton (2000) - A member of the Strumigenys capitata-group. The common dentition of the species serraformis and Strumigenys serradens is unique in the fauna currently under review. It consists of 25 or more minute denticles that are crowded in a serrate row along the masticatory margin of the mandible. The arrangement is immediately reminiscent of the Afrotropical Strumigenys lujae-group, but the similarity is patently by convergence as in the lujae-group the mandible has lost its basal lamella and the clypeus possesses a strange “double” anterior margin. Both serradens and serraformis retain a basal lamella, have a normal clypeal margin and have the preapical denticle distinctly larger than the series immediately preceding it. In these and other characters they conform to the diagnosis of the capitata-group; only the finely serrate mandibles set them apart.

Within the group serraformis and serradens are closely related to Strumigenys rhea, another relatively large species (HW 0.65 or more) from Sulawesi, with which they share the characteristic long low petiole and relatively long mandibles (MI 33-36). They are easily separated as the structure and dentition of the mandible is very different in rhea (see description). Differences separating serraformis from serradens are listed under the latter.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Indonesia, Sulawesi.

Nomenclature

 *  serraformis. Pyramica serraformis Bolton, 2000: 405, figs. 252, 281 (w.m.) INDONESIA (Sulawesi). Combination in Strumigenys: Baroni Urbani & De Andrade, 2007: 127

Bolton (2000) - A single queen from Sulawesi Tengah (in BMNH) is probably referable to serraformis. The characteristic dentition is certainly the same as in serraformis workers, and the habitus of the queen matches that of the described workers, but the queen’s gaster is glassy smooth (as in serradens workers) rather than coriaceous, and is abundantly equipped with standing stout hairs.

Worker
Holotype. TL 3.7, HL 0.78, HW 0.70, CI 90, ML 0.26, MI 33, SL 0.44, SI 63, PW 0.52, AL 1.00. Basal lamella of mandible low and narrow, partially visible in full-face view with the mandibles closed. Basal lamella followed without a diastema by 25 or more minute, closely-packed denticles that form a finely serrate apical margin. Reticulate-punctate sculpture of vertex overlaid by fine irregular rugulae. Apicoscrobal hair stout, somewhat curved, simple and terminating in a blunt or acute point; not flagellate nor remiform/clavate apically. Cephalic dorsum with a transverse row of 4 stout standing hairs close to the occipital margin, and with a single pair of similar hairs just in front of the highest point of the vertex. Hairs on leading edge of scape elongate and very narrowly spatulate, shallowly curved. Eye with 6 ommatidia in the longest row. Pronotal humeral hair stout, slightly curved, pointed apically. Mesonotum with two pairs of standing hairs (one or both members of the anterior pair is frequently lost). Katepistern um smooth; remainder of alitrunk reticulate-punctate everywhere and the pronotum also with irregular fine rugulae. Disc of postpetiole finely sculptured, the sculpture weakest and almost effaced anteromedially where there is a smooth shining patch. Basigastral costulae short, scarcely longer than the limbus; behind them the dorsum of the first gastral tergite covered with extremely fine and dense coriaceous sculpture, superimposed upon which are scattered punctures. Anterior half of first gastral sternite smooth and shining, the posterior half sculptured as the tergite. Propodeal spines short, triangular, base of declivity with a pair of rounded propodeal lobes. Petiole node in profile with a long, shallowly convex dorsum that is much longer than the anterior face of the node. Petiole node in dorsal view conspicuously longer than broad and with a single pair of standing hairs situated close to the posterior spongiform collar. Disc of postpetiole with two pairs of standing hairs, the first gastral tergite hairless (but see discussion under paratypes).

Paratypes. TL 3.7-3.8, HL 0.76-0.83, HW 0.68-0.75, CI 88-91, ML 0.26-0.29, MI 33-35, SL 0.43-0.48, SI 62-64, PW 0.52-0.57, AL 1.00-1.08 (10 measured). As holotype but eye with 5-6 ommatidia in the longest row. Mesonotum properly with two pairs of standing hairs but the majority of paratypes have lost one or both members of the anterior pair. Most paratypes with first gastral tergite hairless (as holotype) but two workers have a single hair close to the limbus and offset from the midline. It seems most likely that a basal pair of hairs should be present in workers but that it is easily lost by abrasion.

Type Material
Holotype worker, Indonesia: Sulawesi (N. Celebes on data label), SW slope Mt Klahat, 400-600 m., 13-19.vi.1972, rain forest, rot. wood (W. L. Brown).

Paratypes. 19 workers and 3 males with same data as holotype; 4 workers Sulawesi (N. Celebes on label), Mt Klabat, Air Madidi slope, 400-600 m., 13-19.vi.1972, wet forest, rotten wood (W. L. Brown) (MCZ,, ).