Nesomyrmex inhaca

Nesomyrmex inhaca is known from the type material; a sample from low vegetation in secondary forest on Inhaca Island, Mozambique.

Identification
A member of the angulatus species-group.

Hita Garcia et al. (2017) - The following character combination distinguishes N. inhaca sp. nov. from the other members of the Nesomyrmex angulatus group: in profile mesosomal dorsum with conspicuously impressed metanotal groove; in dorsal view petiolar node not laterally denticulate; dorsum of propodeum without standing hairs; first gastral tergite with standing hairs evenly distributed throughout.

Within the members of the N. angulatus species group, N. inhaca cannot be mistaken for Nesomyrmex evelynae since the latter is devoid of standing hairs on the first gastral tergite except for a single transverse row on the posterior end of the tergite, and also has very long propodeal spines and a relatively high petiolar node. Nesomyrmex inhaca has short, standing hairs evenly distributed throughout the first gastral tergite, shorter propodeal spines and a much lower petiolar node. The species pair N. angulatus and N. grisoni both do not possess a trace of a metanotal groove, which is obviously present in N. inhaca and thus it is not likely these species will be confused. Nevertheless, N. inhaca is morphologically closer to the trio of species Nesomyrmex denticulatus, Nesomyrmex innocens and Nesomyrmex stramineus. These three are, however, easily separable since they possess a petiolar node with distinct lateral denticles and have standing hairs on the propodeal dorsum, while N. inhaca lacks both the lateral petiolar denticles and the standing hairs on the propodeum. Moreover, N. inhaca has apparently longer antennal scapes based on the much higher SI (94–95) compared to the other three species (SI 67–77). This is partly due to the fact that N. inhaca has indeed relatively longer antennal scapes, but the comparatively narrow head with low values of HW contributes to these high SI values. Therefore, we suggest being cautious with scape length as the single diagnostic character.

Distribution
Hita Garcia et al. (2017) - Known from one collection event on Inhaca Island in the southeast of Mozambique. Despite this apparently restricted distribution to just one island, we are reluctant to declare N. inhaca as endemic to Inhaca Island. With the noticeable exception of the area around Gorongosa, most of Mozambique remains severely under-sampled and our knowledge of local ant communities and species distributions is very poor to non-existent. Consequently, it is possible that N. inhaca will also be found on the mainland.

Distribution based on Regional Taxon Lists
Afrotropical Region: Mozambique.

Nomenclature

 *  inhaca. Nesomyrmex inhaca Hita Garcia et al., 2017: 22, figs. 11A-B, 18 (w.) MOZAMBIQUE.

Worker
HL 0.69–0.73 (0.71); HW 0.50–0.53 (0.51); SL 0.47–0.51 (0.50); EL 0.16–0.17 (0.17); PH 0.26–0.28 (0.27); PW 0.41–0.42 (0.41); WL 0.85–0.88 (0.87); PSL 0.12–0.13 (0.12); PTL 0.14–0.16 (0.15); PTH 0.21–0.22 (0.22); PTW 0.19–0.20 (0.19); PPL 0.18–0.20 (0.19); PPH 0.21–0.22 (0.21); PPW 0.27–0.28 (0.28); CI 71–73 (72); SI 95–98 (96); OI 30–33 (32); DMI 47–49 (48); LMI 31–32 (32); PSLI 16–18 (17); LPeI 64–70 (69); DPeI 127–141 (131); LPpI 86–93 (89); DPpI 140–147 (145); PPI 138–147 (143).

Head. Masticatory margin of mandible with five teeth, decreasing in size from largest, acute apical tooth to smallest basal denticle; clypeus arched-convex to almost triangular, anterior margin with slightly darker, lamellate, flattened ridge all-around; head in full-face view appearing relatively narrow, much longer than broad (CI 71–73), sides of head approximately straight, gently broadening behind eye level, narrowest directly behind posterior eye margin, and widest halfway between posterior eye margin and posterior head margin; posterior head margin concave medially; frontal carinae and antennal scrobes absent; antennal scapes moderately long, not reaching posterior head margin (SI 95–98). Eyes relatively large (OI 29–33), with eight to nine ommatidia in the longest row.

Mesosoma. In lateral view mesosomal outline relatively low (LMI 31–32) and flat with conspicuously impressed metanotal groove; promesonotal suture present laterally and completely absent dorsally; pronotum moderately marginate between lateral and dorsal mesosoma, anterodorsal corners not denticulate; propodeum armed with short to moderately long propodeal spines (PSLI 16–18), in profile spines distinctly longer than their basal width; propodeal lobes low and rounded. Waist segments and gaster. Petiolar peduncle long, anteriorly with a small tooth-like subpetiolar process; in profile petiolar node relatively low and globular, between 1.4 and 1.5 times as high as long (LPeI 64–70); anterior face smoothly merging with peduncle and petiolar dorsum without any angles, posterior face slightly better developed; node in dorsal view about 1.3 to 1.4 times as wide as long (DPeI 127–141); in dorsal view petiolar node not laterally denticulate; in profile postpetiole globular, about 1.1 to 1.2 times as high as long (LPpI 86–93); in dorsal view about 1.4 and 1.5 times as wide as long (DPpI 140–147); postpetiole in dorsal view around 1.4 to 1.5 times as wide as petiolar node (PPI 138–147).

Sculpture. Mandibles shagreened to partly smooth and shiny, sometimes with very weak, superficial, irregular, longitudinal rugulae; median clypeal carina present and conspicuous, usually accompanied by one or two lateral, longitudinal, and slightly weaker rugae on each side; cephalic dorsum posteriorly and laterally strongly reticulate-rugose, medially more irregularly longitudinally rugose, ground sculpture conspicuously reticulate-punctulate; mesosoma laterally and dorsally with distinct reticulate-punctulate ground sculpture, lateral mesosoma conspicuously reticulate-rugose, dorsum reticulate-rugose with some irregular, longitudinal elements medially; legs unsculptured, smooth and shining; petiole and postpetiole with irregular reticulate-rugose sculpture superimposed on reticulate-punctulate ground sculpture; sculpture of first gastral tergite variable, some specimens only with reticulate-punctulate ground sculpture, other specimens irregularly rugose/rugulose on top of reticulate-punctulate ground sculpture.

Pilosity and pubescence. Head, mesosoma, waist segments and gaster dorsally with sparse, erect, blunt, and moderately long pilosity, hairs shorter on head and mesosoma than on waist segments and gaster; head laterally and ventrally with short appressed to decumbent pubescence; pubescence on mesosoma and waist segments sparse to absent; first gastral tergite with short to moderately long, appressed to decumbent pubescence. Coloration. Body uniformly yellowish to light brown, in a few specimens legs slightly lighter yellow, almost white.

Type Material
Holotype. Mozambique: pinned worker, Maputo, Inhaca Island, 26°2′9″ S, 32ｰ54′17″ E, 1 m, secondary forest, low vegetation, 21 Jun. 1992, G.D. Alpert leg. (: MCZ-ENT00593557). Paratypes. Mozambique: 6 pinned workers, same collection data as holotype (: CASENT0790018; : HLMD-Hym-2395; : CASENT0790019; MCZC: CASENT0790017; : CASENT0790022; : CASENT0790020).

Etymology
The new species is named after the type locality, Inhaca Island, to the southeast of Mozambique. The species epithet is a noun in apposition and thus invariant.