Nesomyrmex simoni

Specimens have been collected from pitfall traps in savanna: Pilanesberg Mountain Bushveld (Mucina & Rutherford 2006) vegetation.

Identification
Bolton (1982) - A member of the simoni species-group. A distinctive species characterized by its large size, depressed propodeum, lack of standing hairs on the first gastral tergite, large eyes and short propodeal teeth. The closest relative of simoni is Nesomyrmex braunsi, but in the latter the propodeum is unarmed.

Mbanyana and Robertson (2008) - Nesomyrmex simoni looks similar to Nesomyrmex braunsi and Nesomyrmex saasveldensis in that they all have rugo-reticulate petiolar node and rugo-reticulate sculpture is usually also evident partially or completely on head and mesosoma. It is recognized from N. braunsi by its smaller size (HW 0.783–0.884 versus 1.033–1.109), and armed propodeum (versus unarmed). It is distinguished from N. saasveldensis by lacking hairs on the propodeum.

Distribution based on Regional Taxon Lists
Afrotropical Region: South Africa.

Nomenclature

 *  simoni. Tetramorium simoni Emery, 1895h: 35, pl. 2, fig. 22 (w.) SOUTH AFRICA. Combination in Tetramyrma: Emery, 1924d: 291; in Leptothorax: Bolton, 1982: 331; in Nesomyrmex: Bolton, 2003: 272. See also: Mbanyana & Robertson, 2008: 53.

Worker
Bolton (1982) - TL 4.7, HL 1.10, HW 0.92, CI 84, SL 0.72, SI 78, PW 0.74, AL 1.32.

Mandibles with faint longitudinal sculpture and scattered pits. Median lobe of clypeus prominent, its anterior margin shallowly convex. Median clypeal carina distinct. Frontal carinae and antennal scrobes absent, the scapes of moderate length. Maximum diameter of eye 0.29, about 0.32 x HW and with 17-18 ommatidia in the longest row. With the head in full-face view the occipital margin shallowly convex centrally, more steeply convex laterally where it rounds into the sides. With the alitrunk in profile the promesonotum evenly convex, sloping down posteriorly to the shallow metanotal groove. Propodeal dorsum more shallowly convex than the promesonotum and strongly depressed below the level of the promesonotum. Propodeum armed with a pair of teeth which are slightly shorter than the rounded metapleurallobes. Petiole node massive, domed in profile, the anterior peduncle short and narrow, equipped with a dentiform anteroventral process. In dorsal view both petiole and postpetiole inflated, broader than long. Dorsum of head finely and predominantly longitudinally rugulose, with scattered cross-meshes. On the sides of the head and occipitally a loose reticulum is present. Ground-sculpture between the rugulae a fine dense punctulation, superficial in places. Dorsal surfaces of alitrunk, petiole and postpetiole reticulate-rugose, the meshes narrower and usually more sharply defined on the propodeum and pedicel segments than on the promesonotum. Fine punctulate ground-sculpture present everywhere but stronger on the pedicel segments than on the promesonotum. Base of first gastral tergite finely and very densely reticulate-punctulate, the sculpture weakening posteriorly on the sclerite. Extreme base of first tergite, just behind the postpetiolar articulation, with very short but strongly developed costulae. Short erect hairs very sparse on dorsum of head, absent from all other surfaces except the petiole where a single pair is present. Hairs absent from appendages. Sparse short decumbent to appressed pubescence present on alitrunk and first gastral tergite; hairs present on tergites of gaster behind the first. Head and gaster dark brown with a dull reddish tinge, alitrunk and pedicel segments dull red. Mandibles yellow.

Mbanyana and Robertson (2008) - HL 0.924–1.021, HW 0.783–0.884, HW1 0.850–0.915, CI 83–87, SL 0.649–0.688, SI 78–83, PW 0.615–0.672, ML 1.168–1.268, EL 0.258–0.266, EI 29–33 (3 of 3 measured).

Description matches that of Bolton (1982) except for a few additional characters: promesonotal dorsum with scattered short erect hairs, petiolar node with a pair of subdecumbent hairs and a pair of subdecumbent hairs on the postpetiole; sparse pubescence present.