Holotype. Madagascar. • 1 major worker; Antsiranana; Parc National de Marojejy, 25.7 km 32°NNE Andapa, 10.3 km 314°NW Manantenina; -14.445, 49.74167; alt. 1575 m; 22 Nov 2003; B. L. Fisher leg.; montane rainforest, ex rotten log; BLF09287; CASENT0923257, top specimen on the pin (CASC). Paratypes. • 6w., 2s.; same data as for holotype, CASENT0487334, CASENT0487336, CASENT0487335 (CASC, MHNG, PBZT).

Madagascar. –Antsiranana: • 6w., 3s.; Parc National de Marojejy, 25.4 km 30°NNE Andapa, 10.9 km 311°NW Manantenina; -14.445, 49.735; alt. 2000 m; 23 Nov 2003; B. L. Fisher leg.; montane shrubland, under moss, on ground; BLF09330 (CASC). •1w.; Parc National de Marojejy, 25.7 km 32°NNE Andapa, 10.3 km 314°NW Manantenina; -14.445, 49.74167; alt. 1575 m; 21 Nov 2003; B. L. Fisher leg.; montane rainforest; sifted litter (leaf mold, rotten wood); BLF09242 (CASC). • 6w.; Parc National de Marojejy, 25.7 km 32°NNE Andapa, 10.3 km 314°NW Manantenina; -14.445, 49.74167; alt. 1575 m; 22 Nov 2003; B. L. Fisher leg.; montane rainforest, under moss, above ground; BLF09264 (CASC). • 6w., 3s.; Parc National de Marojejy, 25.7 km 32°NNE Andapa, 10.3 km 314°NW Manantenina; -14.445, 49.74167; alt. 1575 m; 22 Nov 2003; B. L. Fisher leg.; montane rainforest, ex rotten log; BLF09302 (CASC). • 3w.; Parc National de Marojejy, 25.7 km 32°NNE Andapa, 10.3 km 314°NW Manantenina; -14.445, 49.74167; alt. 1575 m; 22 Nov 2003; B. L. Fisher leg.; montane rainforest, ex Melastomataceae; BLF09318 (CASC). • 3w.; Parc National de Marojejy, Antranohofa, 26.6 km 31°NNE Andapa, 10.7 km 318°NW Manantenina; -14.44333, 49.74333; alt. 1325 m; 19 Nov 2003; B. L. Fisher leg.; montane rainforest, under moss, above ground; BLF09142 (CASC). • 1w.; Prov. Antsiranana R.S. Manongarivo 17.3 km 218°SW Antanambao; -14.02167, 48.41833; alt. 1580 m; 27 Oct 1998; B. L. Fisher leg.; montane rainforest, sifted litter (leaf mold, rotten wood); BLF01970 (CASC). • 3w.; Prov. Antsiranana R.S. Manongarivo 17.3 km 218°SW Antanambao; -14.02167, 48.41833; alt. 1580 m; 27 Oct 1998; B. L. Fisher leg.; montane rainforest; BLF01972 (CASC). • 1w.; R.S. Manongarivo, 20.4 km 219°SW Antanambao; -14.04667, 48.40167; alt. 1860 m; 3 Nov 1998; B. L. Fisher leg.; montane rainforest; BLF01989 (CASC). –Mahajanga: • 10w.; Region Sofia, Ampotsidia; -14.40775, 48.70201; alt. 1625 m; 10 Jan 2017; B. L. Fisher leg.; montane rainforest, sifted litter; BLF39733 (CASC).

Moderately large species. Major workers. Head in full-face view sub-oval and slightly widening posteriorly, with anterior and posterior sides slightly convex, in lateral view sub-oval; ventral and dorsal faces convex; sides of the head with moderately dense, long, suberect to erect pilosity; medial part of frons with thick, interrupted, dense, and longitudinal rugae with smooth to indistinctly rugulate interspaces; occipital lobes and area posterolateral from eyes without smooth notches; scape, when laid back, exceeding the midlength of head by one-fifth of its length; inner hypostomal teeth indistinct, low, and wide, closely spaced, bulge-like; outer hypostomal teeth lobe-like, wider and higher than inner teeth, apex directed upward; inner and outer hypostomal teeth closely spaced and not connected by concavity; mesosoma rugofoveolate; pronotum with additional thin, moderately dense, and transverse rugae; katepisternum with reduced sculpture and sometimes with smooth notch; gaster smooth; body black. Minor workers. Head foveolate; median frons with short, indistinct, and longitudinal rugulae; area posterolateral from eyes with slightly to distinctly weaker sculpture; scape, when laid back, exceeding the posterior head margin by one-third of its length; promesonotum low and moderately long; promesonotal groove present; propodeal spines small and triangular; mesosoma foveolate; katepisternum with reduced sculpture or with smooth notch; body black to dark brown.

Major workers. Measurements (N = 9): HL: 1.3–1.79 (1.61); HW: 1.28–1.73 (1.56); SL: 0.88–1.05 (0.97); EL: 0.18–0.22 (0.19); WL: 1.22–1.48 (1.36); PSL: 0.22–0.28 (0.26); MTL: 0.91–1.07 (1.01); PNW: 0.54–0.7 (0.61); PTW: 0.16–0.22 (0.2); PPW: 0.35–0.53 (0.44); CI: 100.7–104.7 (102.9); SI: 57.5–70.4 (62.9); PSLI: 14.9–17.7 (16.1); PPI: 41.6–49.1 (45.1); PNI: 36.3–43.7 (39.4); MTI: 60.3–73.4 (65.4).

Head. In full-face view sub-oval, slightly widening posteriorly, with anterior and posterior sides convex (Fig. 19B). In lateral view sub-oval; ventral and dorsal faces convex; inner hypostomal teeth visible. Sides of the head with moderately dense, long, suberect to erect pilosity; whole head with dense, long, decumbent to erect pilosity. Medial part of frons with thick, interrupted, dense, and longitudinal rugae with smooth to indistinctly rugulate interspaces; lateral sides of frons with denser, thick, and longitudinal rugae, interspaces with dense and moderately thick rugulae. Occipital lobes with longitudinal and thinner rugae and indistinctly rugulate to smooth interspaces. Area posterolateral from eyes with dense, thick, and longitudinal rugae with distinctly rugulate interspaces, sculpture fading posteriorly. Gena with relatively sparse, thick, and longitudinal rugae with indistinctly rugulate 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 one-fifth of its length; pilosity subdecumbent to erect (Fig. 19B, D). Inner hypostomal teeth indistinct, low, and wide, closely spaced, bulge-like; outer hypostomal teeth lobe-like, wider, and higher than inner teeth, apex directed upward; inner and outer hypostomal teeth closely spaced and not connected by concavity (Fig. 63A). Mesosoma. In lateral view, promesonotum short, angular, and moderately low, posterior mesonotum moderately steep, mesonotal process indistinct, tubercle-like; promesonotal groove absent; metanotal groove absent; propodeal spines moderately long, narrow, and with acute apex; humeral area weakly produced (Fig. 19D). Surface shiny and rugofoveolate; pronotum with additional thin, moderately dense, and transverse rugae; katepisternum with reduced sculpture and sometimes with smooth notch. Pilosity moderately dense, long, and erect (Fig. 19D, F). Petiole. Shiny with sparse foveolae; node finely foveolate to smooth, triangular, with rounded and thick apex, in rear view node dorsoventrally slightly convex; pilosity moderately sparse and erect (Fig. 19D, F). Postpetiole. Shiny and foveolate; dorsum with reduced sculpture and smooth notch; in dorsal view oval, lateral margins medially with two wide and dentate projections; pilosity long, moderately sparse, and erect (Fig. 19D, F). Gaster. Shiny and smooth; pilosity moderately sparse, long, and erect (Fig. 19D, F). Colour. Black, gena and posterior parts of lateral sides of promesonotum reddish, gaster, antenna, and legs yellowish (Fig. 19D, F).

Minor workers. Measurements (N = 10): HL: 0.65–0.85 (0.78); HW: 0.5–0.65 (0.61); SL: 0.87–1.07 (1.04); EL: 0.12–0.16 (0.14); WL: 0.89–1.12 (1.07); PSL: 0.11–0.17 (0.15); MTL: 0.72–0.89 (0.86); PNW: 0.37–0.47 (0.44); PTW: 0.08–0.13 (0.11); PPW: 0.15–0.21 (0.18); CI: 123.6–131.1 (127.5); SI: 155.1–172.1 (163.4); PSLI: 16.8–21.0 (19.1); PPI: 45.9–69.9 (58.8); PNI: 69.0–75.0 (71.8); MTI: 136.3–143.7 (139.7).

Head. Cephalic margin slightly convex (Fig. 19A). Pilosity relatively sparse, short, and subdecumbent. Sculpture shiny and foveolate; median frons with short and indistinct longitudinal rugulae; area posterolateral from eyes with slightly to distinctly weaker sculpture; antennal sockets with few indistinct, curved outward rugae and foveolate interspaces. Clypeus with median longitudinal carina absent; two lateral longitudinal carinae absent. Scape, when laid back, exceeding the posterior head margin by one-third of its length; pilosity dense, subdecumbent to erect (Fig. 19A, C). Mesosoma. In lateral view, promesonotum low and moderately long, arched; promesonotal groove indistinct; metanotal groove distinct; propodeal spines small and triangular (Fig. 19C). Sculpture shiny and foveolate; katepisternum with reduced sculpture or with smooth notch. Pilosity sparse, moderately long, and erect (Fig. 19C, E). Gaster. With sparse, erect pilosity (Fig. 19C, E). Colour. Black to dark brown, legs, gaster, and antenna yellowish (Fig. 19C, E).

Malagasy for night in reference to dark body colouration.

The species was collected between 1270–2000 m in elevation, in montane rainforest and montane shrubland. Nests were located in rotten logs, under moss above and on the ground, and in a Melastomataceae twig.

Pheidole alina sp. nov. belongs to the group of taxa characterised by dark body colouration, in major workers from brownish black to black and in minor workers from black (head and mesosoma) to dark brown with body predominantly foveolate (in dark brown specimens entirely). The group consists of three species: P. alina sp. nov., P. trichotos sp. nov., and P. mainty sp. nov. All members of this group are sympatric and their distribution is limited to northernmost parts of the island, predominantly in Antsiranana prefecture. Major workers of Pheidole alina sp. nov. differ from P. trichotos sp. nov. by medial part of frons with thick, interrupted, dense, and longitudinal rugae with smooth to indistinctly rugulate interspaces, base of first gastral tergite smooth and indistinct, bulge-like inner hypostomal teeth; from P. mainty sp. nov. in sides of the head with moderately dense, long, suberect to erect pilosity, indistinct, bulge-like inner hypostomal teeth, and narrow and moderately long propodeal spines. Minor workers of P. alina sp. nov. differ from P. trichotos sp. nov. in larger body size and black body colouration; from P. mainty sp. nov. in never entirely smooth area posterolateral from eyes and distinctly foveolate mesosoma with reduced or no foveolae only on the katepisternum.