Holotype. Madagascar. •1 major worker; Toliara; Grand Lavasoa, 25.9km W Tolagnaro; -25.08767, 46.749; alt. 450 m; 30 Nov 2006; B. L. Fisher et al. leg.; rainforest, ex rotten log; BLF15392; CASENT0122898 (CASC). Paratype. •1w.; same data as for holotype, CASENT0923282 (CASC).

Minute species. Major workers.HL < 0.95 mm and WL < 0.8 mm; head in full-face view sub-oval; body dark brown; sides of head with very dense, short, suberect pilosity; entire head distinctly sculptured; scape, when laid back, exceeding the midlength of head by two-fifths of its length; inner hypostomal teeth distinct, large, with rounded apex; outer hypostomal teeth dentate with apex directed indistinctly outward; inner and outer hypostomal teeth not closely spaced and not connected by concavity. Minor workers.HL < 0.5 mm and WL < 0.6 mm, scape, when laid back, surpassing the posterior head margin by two-fifths of its length, propodeal spines reduced to small lobes, head elongate, and oval and body yellowish brown; head sculpture shiny and predominantly smooth, frons with sparse, short, and longitudinal rugulae; mesosoma shiny and smooth.

Major workers. Measurements (N = 1): HL: 0.94; HW: 0.98; SL: 0.66; EL: 0.12; WL: 0.83; PSL: 0.13; MTL: 0.57; PNW: 0.36; PTW: 0.13; PPW: 0.28; CI: 95.6; SI: 67.0; PSLI: 13.9; PPI: 44.0; PNI: 36.3; MTI: 57.9.

Head. In full-face view sub-oval, slightly widening posteriorly, with anterior and posterior sides convex (Fig. 37B). In lateral view sub-oval; ventral and dorsal faces convex; inner hypostomal teeth visible. Sides of the head with very dense, short, suberect to erect pilosity; whole head with dense, long, decumbent to erect pilosity. Medial part of frons with thick, dense, longitudinal and interrupted rugae and smooth interspaces, posteromedial frons with rugae more irregular and directed slightly outward; lateral sides with thick, dense, and irregular rugae, interspaces shiny and smooth or indistinctly rugulate. Occipital lobes with thick, irregular rugae and smooth to rugoreticulate interspaces. Area posterolateral from eyes rugoreticulate to rugofoveolate with additional longitudinal thick rugae. Gena with relatively dense, thick, and longitudinal rugae and smooth to indistinctly rugoreticulate interspaces. Centre of clypeus smooth and shiny, lateral sides with indistinct rugulae; median notch present, moderately wide, and shallow; median longitudinal carina present; lateral longitudinal carinae absent. Scape, when laid back, exceeding the midlength of head by three-fifths of its length; pilosity subdecumbent to erect (Fig. 37B, D). Inner hypostomal teeth distinct, large, closely spaced, triangular, with rounded apex directed upward; outer hypostomal teeth dentate and lower than inner teeth with sharp apex directed slightly outward; inner and outer hypostomal teeth not closely spaced and not connected by concavity (Fig. 63S). Mesosoma. In lateral view, promesonotum short, angular, and moderately low, posterior mesonotum moderately steep, mesonotal process very indistinct, tubercle-like; promesonotal groove absent; metanotal groove absent; propodeal spines moderately short, with moderately wide base and acute apex; humeral area laterally weakly produced (Fig. 37D). Surface shiny with fine rugofoveolae; medial parts of lateral sides of pronotum with reduced sculpture. Pilosity moderately dense, long, and erect (Fig. 37D, F). Petiole. Shiny with fine foveolae; node smooth to finely foveolate, triangular, with rounded and thick apex, in rear view node dorsoventrally straight to slightly convex; pilosity moderately sparse and erect (Fig. 37D, F). Postpetiole. Shiny and foveolate; dorsum with reduced sculpture and smooth notch; in dorsal view oval, lateral margins medially with two dentate projections; pilosity long, moderately sparse, and erect (Fig. 37D, F). Gaster. Shiny and smooth; pilosity dense, long, and erect (Fig. 37D, F). Colour. Dark brown; legs, gaster and antennae yellowish brown (Fig. 37D, F).

Minor workers. Measurements (N = 1): HL: 0.48; HW: 0.42; SL: 0.54; EL: 0.1; WL: 0.58; PSL: 0.05; MTL: 0.4; PNW: 0.27; PTW: 0.07; PPW: 0.11; CI: 116.4; SI: 130.8; PSLI: 9.7; PPI: 65.5; PNI: 65.1; MTI: 95.4.

Head. Cephalic margin indistinctly convex (Fig. 37A). Pilosity relatively dense, long, decumbent to suberect. Sculpture shiny and smooth; frons with sparse, short, and longitudinal rugulae; antennal sockets with few thick, curved outward rugae and smooth interspaces. Clypeus with median longitudinal carina absent; two lateral longitudinal carinae absent. Scape, when laid back, surpassing the posterior head margin by two-fifths of its length; pilosity dense, subdecumbent to erect (Fig. 37A, C). Mesosoma. In lateral view, promesonotum moderately high and short, arched; promesonotal groove absent; metanotal groove distinct; propodeal spines reduced to small lobes (Fig. 37C). Sculpture shiny and smooth. Pilosity moderately sparse, long, and erect (Fig. 37C, E). Gaster. With sparse, erect pilosity (Fig. 37C, E). Colour. Yellowish brown (Fig. 37C, E).

From the type locality.

The species was collected at 450 m in elevation, in rainforest. Nest was located in a rotten log.

Pheidole lavasoa sp. nov., described from Grand Lavasoa, Toliara, resembles the parapatric species P. andohahela sp. nov. known to date from Col de Tanatana in Parc National Andohahela, Toliara. Major workers of both taxa are very similar and can be separated based on slight difference in setosity of lateral sides of head (which is denser and shorter in Pheidole lavasoa sp. nov.) and shape of hypostomal teeth (P. lavasoa sp. nov. has inner hypostomal teeth with rounded apex and outer hypostomal teeth are dentate and indistinctly directed outward). A better resource for species separation are minor workers. Minor workers of Pheidole lavasoa sp. nov. lack transverse rugulae on vertex and frons and their frons have sparse, short, and longitudinal rugulae, mesosoma is entirely smooth, and body is yellowish brown.