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; BLF36492; CASENT0704280 (CASC). Paratypes. • 2w., 1m.; same data as for holotype; CASENT0923290, CASENT0704279 (CASC, MHNG).

Madagascar. –Toliara: • 2w., 1s., 1m.; 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, under stone; BLF36463 (CASC). • 2w.,1s., 1q.; 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, under root mat on rock; BLF36477 (CASC). •2 w., 1s., 1m.; 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; BLF36496 (CASC). • 1w., 1s.; 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 rotten log; BLF36561 (CASC).

Minute species. Major workers.HL < 1.1 mm and WL < 0.9 mm; head, in full-face view, sub-oval, slightly widening posteriorly, with anterior and posterior sides convex, in lateral view sub-oval; ventral and dorsal faces convex; body dark orange; sides of head with moderately dense, moderately long, subdecumbent to suberect pilosity; entire head distinctly sculptured, medial part of frons with longitudinal rugae, rugae in posteromedial part more irregular, interspaces shiny with dense, distinct, and irregular rugulae; scape, when laid back, slightly exceeding the midlength of head; mesosoma predominantly rugofoveolate, pronotal dorsum and lateral sides of propodeum with reduced sculpture; inner hypostomal teeth distinct, moderately high, closely spaced, triangular, with rounded apex directed upward; outer hypostomal teeth lobe-like, wider and higher than inner hypostomal teeth, apex directed outward; inner and outer hypostomal teeth closely spaced, connected by indistinct concavity; base of first gastral tergite smooth. Minor workers.HL < 0.5 mm and WL < 0.6 mm, scape, when laid back, surpassing the posterior head margin by one-fifth of its length; propodeal spines very small, triangular; head relatively rectangular; body yellow; head foveolate, frons with additional indistinct longitudinal and interrupted rugae in medial part, area posterolateral from eyes smooth; mesosoma smooth.

Major workers. Measurements (N = 4): HL: 0.99–1.06 (1.02); HW: 1.0–1.05 (1.0); SL: 0.55–0.56 (0.56); EL: 0.12–0.12 (0.12); WL: 0.85–0.91 (0.88); PSL: 0.18–0.2 (0.19); MTL: 0.53–0.55 (0.54); PNW: 0.46–0.48 (0.47); PTW: 0.11–0.16 (0.14); PPW: 0.24–0.31 (0.27); CI: 98.7–103.1 (101.2); SI: 53.4–56.7 (55.2); PSLI: 17.1–20.5 (18.6); PPI: 40.6–60.4 (52.2); PNI: 45.3–48.9 (46.3); MTI: 52.3–56.0 (53.7).

Head. In full-face view sub-oval, slightly widening posteriorly, with anterior and posterior sides convex (Fig. 32B). In lateral view sub-oval; ventral and dorsal faces convex; inner hypostomal teeth visible. Sides of the head with moderately dense, moderately long, subdecumbent to suberect pilosity; whole head with dense, long, decumbent to erect pilosity. Medial part of frons with moderately dense, thick, longitudinal rugae, rugae in posteromedial part more irregular and directed outward, interspaces shiny with dense and distinct irregular rugulae; lateral sides with longitudinal to irregular and thick rugae with distinctly rugofoveolate interspaces. Occipital lobes with sparse, thick, and irregular rugae; interspaces smooth to indistinctly rugulate. Gena with relatively dense and thick longitudinal rugae and distinctly rugofoveolate interspaces. Area posterolateral from eyes with dense and thick rugofoveolae. 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, slightly exceeding the midlength of head; pilosity decumbent to erect (Fig. 32B, D). Inner hypostomal teeth distinct, moderately high, closely spaced, triangular, with rounded apex directed upward; outer hypostomal teeth lobe-like, wider and higher than inner hypostomal teeth, apex directed outward; inner and outer hypostomal teeth closely spaced, connected by indistinct concavity (Fig. 63N). Mesosoma. In lateral view, promesonotum short, angular, and moderately high, posterior mesonotum moderately steep, mesonotal process indistinct, tubercle-like; promesonotal groove absent; metanotal groove absent; propodeal spines moderately long, moderately wide, with acute apex; humeral area laterally weakly produced (Fig. 32D). Surface shiny and predominantly rugofoveolate, pronotal dorsum and lateral sides of propodeum with reduced sculpture. Pilosity relatively dense, long, and erect (Fig. 32D, F). Petiole. Shiny with fine and dense rugofoveolae; node partially smooth, low, triangular, with rounded and thin apex, in rear view node dorsoventrally slightly concave; pilosity moderately sparse and erect (Fig. 32D, F). Postpetiole. Shiny and smooth; in dorsal view oval, lateral margins medially with two dentate projections; pilosity long, moderately sparse, and erect (Fig. 32D, F). Gaster. Shiny and smooth; pilosity moderately dense, long, and erect (Fig. 32D, F). Colour. Dark orange; legs yellow (Fig. 32D, F).

Minor workers. Measurements (N = 5): HL: 0.52–0.53 (0.52); HW: 0.44–0.47 (0.45); SL: 0.51–0.53 (0.52); EL: 0.09–0.11 (0.09); WL: 0.6–0.62 (0.61); PSL: 0.05–0.08 (0.07); MTL: 0.39–0.41 (0.4); PNW: 0.28–0.33 (0.3); PTW: 0.06–0.09 (0.07); PPW: 0.12–0.13 (0.12); CI: 112.2–118.6 (115.6); SI: 112.2–115.8 (114.1); PSLI: 10.3–14.3 (12.9); PPI: 50.4–70.5 (58.2); PNI: 63.4–69.3 (66.7); MTI: 87.2–90.2 (88.4).

Head. Cephalic margin indistinctly concave or straight (Fig. 32A). Pilosity relatively sparse, long, decumbent to subdecumbent. Sculpture foveolate; frons with additional indistinct longitudinal and interrupted rugae in medial part; 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. 32A, C). Mesosoma. In lateral view, promesonotum moderately low and short, arched; promesonotal groove absent; metanotal groove present and distinct; propodeal spines very small and triangular (Fig. 32C). Sculpture smooth. Pilosity very sparse, moderately long, and erect (Fig. 32C, E). Postpetiole. Short, low, and relatively flat; with few short, erect setae (Fig. 32C, E). Gaster. With sparse, erect pilosity (Fig. 32C, E). Colour. Yellow, vertex slightly darker (Fig. 32C, E).

Malagasy for hill or mountain in reference to type locality.

The species was collected at 1125 m in elevation, in rainforest. Nests were located in rotten logs under stone and in root mats.

Pheidole havoana sp. nov. belongs to the group of species characterised by small body size (major workers: HL < 1.05 mm, WL < 0.9 mm and minor workers HL < 0.5 mm, WL < 0.6 mm), head sub-oval, slightly widening posteriorly with anterior and posterior sides convex in major workers, and minor workers with yellow to brown body colouration and head foveolate or predominantly smooth and relatively oval. The group includes six species: P. havoana sp. nov., P. kely sp. nov., P. parvula sp. nov., P. parvulogibba sp. nov., P. volontany sp. nov., and P. midongy sp. nov. Within this group, P. havoana sp. nov., described form Anosyenne Mts. in Toliara, is most similar to P. kely sp. nov., distributed in the northern part of the island, P. parvula sp. nov., known from two localities in the vicinity of Antananarivo, and sympatric P. parvulogibba sp. nov. Minor workers of P. havoana sp. nov. distinctly differ from those of P. parvula sp. nov. and P. parvulogibba sp. nov. by predominantly foveolate head and presence of additional indistinct longitudinal and interrupted rugae in medial part of frons. Minor workers of P. havoana sp. nov. and P. kely sp. nov. are indistinguishable. Major workers of P. havoana sp. nov. differ from P. kely sp. nov. and P. parvulogibba sp. nov. by medial part of frons with longitudinal rugae, rugae in posteromedial part more irregular, with densely and distinctly irregular rugulae in interspaces; and from P. parvula sp. nov. in reduced sculpture on pronotal dorsum and lateral sides of propodeum.