Nesomyrmex stramineus

Mbanyana and Robertson (2008) - Nests in dead wood on trees. Specimens have been collected from savanna woodland and Afromontane forest.

Identification
Hita Garcia et al. (2017) - A member of the angulatus species-group. The following character combination distinguishes N. stramineus from the other species of the group: eyes with 7–9 ommatidia in longest row; in profile mesosomal dorsum with conspicuously impressed metanotal groove; propodeal spines relatively long and thin, several times longer than their basal width; in profile petiolar node high, rectangular nodiform, appearing around twice as high as long; in dorsal view petiolar node laterally denticulate; subpetiolar process without a long cuticular flange running back to the postpetiolar junction; dorsum of propodeum with standing hairs; first gastral tergite with standing hairs evenly distributed throughout.

 Nesomyrmex stramineus is very close to Nesomyrmex denticulatus and Nesomyrmex innocens. For more details on its differentiation from them we refer to the species account of N. innocens.

Among the species which have the metanotal groove impressed stramineus is most closely related to Nesomyrmex innocens, the two species sharing the characters of relatively small eyes and having short hairs on the first gastral tergite (as opposed to the first gastral tergite being hairless). In fact, stramineus and innocens form an extremely close species-pair and may eventually prove to be expressions of a single species. For the present the two may be separated as the sculpture in innocens, although punctulate as in stramineus, is much more strongly developed and sharply defined, with traces of rugular sculpture also present at least on the head. Besides this the petiolar tubercles are not as strongly developed in innocens as they are in stramineus, and the propodeal spines are shorter and broader.

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

Nomenclature

 *  stramineus. Limnomyrmex stramineus Arnold, 1948: 223, fig. 10 (w.) SOUTH AFRICA. Combination in Leptothorax: Brown, 1971a: 4; in Nesomyrmex: Bolton, 2003: 272. See also: Bolton, 1982: 332; Mbanyana & Robertson, 2008: 38.

Worker
Bolton (1982) - TL 2.8, HL 0.63, HW 0.53, CI 84, SL 0.36, SI 68, PW 0.38, AL 0.68.

Mandibles very delicately shagreened, almost smooth. Median portion of clypeus with anterior margin evenly arcuate-convex, with a very narrow cuticular apron. Median clypeal carina vestigial. Frontal carinae and antennal scrobes absent, the antennal scapes short. Maximum diameter of eye 0.13, about 0.25 x HW and with 7-8 ommatidia in the longest row. Sides of head behind eyes very feebly convex, the sides narrowing in front of the eyes so that the width immediately in front of the eyes is 0.47 and across the clypeus at its widest is 0.38 (compare with HW 0.53). Occipital margin approximately straight and the occipital corners evenly rounded. Alitrunk in profile with promesonotum evenly and shallowly convex, the propodeal dorsum on the same level but shorter and more strongly convex, the two convexities separated by the conspicuously impressed metanotal groove. Propodeal spines narrow and somewhat down curved along their length, longer than their basal widths. Slope of the declivity between the spines and the rounded metapleural lobes straight. In dorsal view the alitrunk with the pronotal shoulders obtusely and bluntly angled, the promesonotum narrowing posteriorly to the metanotal groove. Behind this the propodeum broadening to the level of the spiracle then narrowing again to the bases of the spines; the latter divergent and in the holotype with the right spine slightly longer than the left. Petiole node in dorsal view with a strong lateral tubercle on each side, a pair of smaller tubercles on the posterior margin and a very feeble pair anterodorsally which are almost effaced. Post petiole with a low but broad lateral tubercle on each side. In profile the petiole peduncle short, with a small triangular anteroventral process and with a very small sub-denticulate process dorsally. The node itself higher than long, the lateral and posterior tubercles distinct. Sides of first gastral tergite in dorsal view curving evenly away from the articulation with the post petiole, without a sharp, flattened appearance. Head, alitrunk, petiole and pcstpetiole very finely and very densely superficially reticulate-punctulate, without rugulose sculpture. First gastral tergite with only the faintest vestiges of superficial sculpture basally. Dorsal surfaces of head and body with scattered very short blunt stout hairs; such hairs absent from appendages and sides of head but one or two may project from the curved part of the occipital corner on each side. Colour uniform pale yellow.

References based on Global Ant Biodiversity Informatics

 * Hita Garcia F., Mbanyana N., Audisio T. L., and G. D. Alpert. 2017. Taxonomy of the ant genus Nesomyrmex Wheeler (Formicidae, Myrmicinae) in the Afrotropical region, with a review of current species groups and description of a new species of the N. angulatus group from Mozambique. European Journal of Taxonomy 258: 1–31.
 * IZIKO South Africa Museum Collection
 * Mbanyana N., and H. G. Robertson. 2008. Review of the ant genus Nesomyrmex (Hymenoptera: Formicidae: Myrmicinae) in southern Africa. African Natural History 4: 35-55.