Holotype. Madagascar. • 1 major worker; Toliara; Anosy Region, Anosyenne Mts, 31.2 km NW Manantenina; -24.13894, 47.06804; alt. 1125 m; 26 Feb 2015; B. L. Fisher et al. leg.; rainforest, ex root mat; BLF36559; CASENT0704282 (CASC). Paratype. • 1w.; same data as for holotype; CASENT0923293 (CASC).

Moderately large species. Major workers. Head in full-face view sub-oval and not widening posteriorly, with anterior and posterior sides slightly convex, in lateral view sub-oval; ventral and dorsal faces convex; sides of the head with very dense, long, erect pilosity; medial part of frons with moderately dense, thick, interrupted longitudinal rugae, interspaces smooth; occipital lobes smooth and shiny; area posterolateral from eyes with reduced sculpture and smooth notch; scape, when laid back, exceeding the midlength of head by approximately two-fifths of its length; inner hypostomal teeth distinct, moderately high, closely spaced, triangular, with rounded apex slightly directed outward; outer hypostomal teeth lobe-like, wider and higher than inner hypostomal teeth, apex directed outward; inner and outer hypostomal teeth closely spaced but not connected; mesosoma predominantly smooth, indistinct, thin, sparse, and irregular rugae occur on lateral sides; body yellow. Minor workers. Medial part of frons with sparse and fading foveolae and short, longitudinal rugae; lateral sides with thicker and denser foveolae and longitudinal, interrupted, and thick rugae; area posterolateral from eyes smooth; scape, when laid back, surpassing the posterior head margin by one-fifth of its length; promesonotum moderately low and short; promesonotal groove present; propodeal spines minute and triangular; mesosoma smooth with indistinct foveolae on posterior katepisternum; body yellow.

Major workers. Measurements (N = 1): HL: 1.05; HW: 1.05; SL: 0.59; EL: 0.15; WL: 1.0; PSL: 0.17; MTL: 0.64; PNW: 0.48; PTW: 0.16; PPW: 0.26; CI: 100.1; SI: 56.4; PSLI: 16.2; PPI: 59.8; PNI: 45.5; MTI: 61.0.

Head. In full-face view sub-oval, not widening posteriorly, with anterior and posterior sides convex (Fig. 43B). In lateral view sub-oval; ventral and dorsal faces convex; inner hypostomal teeth invisible. Sides of the head with very dense, long, erect pilosity; whole head with dense, long, decumbent to erect pilosity. Medial part of frons with moderately dense, thick, interrupted longitudinal rugae, interspaces smooth; lateral sides with longitudinal and thick rugae with distinctly rugofoveolate interspaces. Occipital lobes smooth and shiny. Gena with relatively dense, thick, and longitudinal rugae and distinctly rugofoveolate interspaces. Area posterolateral from eyes with reduced sculpture and smooth notch. Centre of clypeus smooth and shiny, lateral sides with indistinct rugulae; median notch present, moderately wide, and shallow; median longitudinal carina absent; lateral longitudinal carinae absent. Scape, when laid back, exceeding the midlength of head by approximately two-fifths of its length; pilosity decumbent to erect (Fig. 43B, D). Inner hypostomal teeth distinct, moderately high, closely spaced, triangular, with rounded apex slightly directed outward; outer hypostomal teeth lobe-like, wider and higher than inner hypostomal teeth, apex directed outward; inner and outer hypostomal teeth closely spaced but not connected (Fig. 64A). Mesosoma. In lateral view, promesonotum short, angular, and moderately high, posterior mesonotum moderately steep, mesonotal process indistinct, tubercle-like; promesonotal groove absent; metanotal groove indistinct; propodeal spines moderately long, wide, with acute apex; humeral area laterally weakly produced (Fig. 43D). Surface shiny and predominantly smooth, indistinct, thin, sparse, and irregular rugae occur on lateral sides. Pilosity relatively dense, long, and erect (Fig. 43D, F). Petiole. Shiny with fine and sparse rugofoveolae; peduncle; node smooth, low, triangular, with rounded and thin apex, in rear view node dorsoventrally convex; pilosity moderately sparse and erect (Fig. 43D, F). Postpetiole. Shiny and smooth; in dorsal view oval, lateral margins medially with two dentate projections; pilosity long, moderately sparse, and erect (Fig. 43D, F). Gaster. Shiny and smooth; pilosity moderately dense, long, and erect (Fig. 43D, F). Colour. Yellow; mandibles and gaster slightly darker (Fig. 43D, F).

Minor workers. Measurements (N = 1): HL: 0.61; HW: 0.56; SL: 0.58; EL: 0.11; WL: 0.77; PSL: 0.09; MTL: 0.5; PNW: 0.35; PTW: 0.09; PPW: 0.16; CI: 109.7; SI: 103.8; PSLI: 14.1; PPI: 58.5; PNI: 62.5; MTI: 90.8.

Head. Cephalic margin indistinctly convex or occipital carina absent (Fig. 43A). Pilosity relatively sparse, long, decumbent to subdecumbent. Medial part of frons with sparse and fading foveolae and short, longitudinal rugae; lateral sides with thicker and denser foveolae and longitudinal, interrupted, and thick rugae; area posterolateral from eyes smooth. Clypeus with median longitudinal carina absent; two lateral longitudinal carinae absent. Scape, when laid back, surpassing the posterior head margin by one-fifth of its length; pilosity dense, subdecumbent to erect (Fig. 43A, C). Mesosoma. In lateral view, promesonotum moderately high and short, arched; promesonotal groove present and distinct; metanotal groove present and distinct; propodeal spines minute and triangular (Fig. 43C). Sculpture smooth with indistinct foveolae on posterior katepisternum. Pilosity sparse, moderately long, and erect (Fig. 43C, E). Petiole. Peduncle short and thin with ventral face relatively straight(Fig. 43C, E). Postpetiole. Short, low, and relatively flat; with few short, erect setae (Fig. 43C, E). Gaster. With sparse, erect pilosity (Fig. 43C, E). Colour. Yellow, vertex and gaster slightly darker (Fig. 43C, E).

Malagasy for sun, in reference to bright yellow body colouration.

The species was collected at 1125 m in elevation, in rainforest. Nest was located in root mat.

Pheidole masoandro sp. nov. is a member of a group of species characterised by distinctly reduced head sculpture in major workers with occipital lobes entirely or predominantly smooth, area posterolateral from eyes partially or entirely smooth and shiny or with reduced sculpture and smooth notches. The group consists of four species: P. litigiosa, P. masoandro sp. nov., P. gracilis sp. nov., and P. tampony sp. nov. Pheidole masoandro sp. nov. is the only member of this group known from the Anosyenne Mts. in Toliara. Morphologically P. masoandro sp. nov. is most similar to P. litigiosa distributed in the Antananarivo prefecture. Its major workers can be separated based on medial part of frons with moderately dense, thick, interrupted, and longitudinal rugae and smooth interspaces, sides of the head with very dense, long, erect pilosity, and outer hypostomal teeth lobe-like, wider and higher than inner hypostomal teeth with apex directed outward; minor workers have distinct promesonotal groove, their propodeal spines are minute and triangular, and frons have additional short rugae. Despite strong morphological differences in major workers, minor workers of P. masoandro sp. nov., P. sikorae and P. antranohofa sp. nov. are indistinguishable.