Holotype. Madagascar. • 1 major worker; Mahajanga; Réserve forestière Beanka, 53.6 km E Maintirano; -18.04014, 44.53394; alt. 272 m; 25 Oct 2009; B. L. Fisher et al. leg.; tropical dry forest on tsingy, ex rotten log; BLF22970; CASENT0156684 (CASC). Paratype. • 1w.; same data as for holotype, CASENT0923276 (CASC).

Minute species. Major workers.HL < 0.9 mm and WL < 0.7 mm; head in full-face view elongate, not widening posteriorly with posterior sides slightly convex, in lateral view sub-oval and short with convex dorsal and ventral sides; body ocherous; sides of head with moderately dense, moderately short, suberect to erect pilosity; entire head distinctly sculptured, medial part of frons with thick and longitudinal rugae and distinctly rugulate and never smooth interspaces, occipital lobes with dense and irregular rugae with distinctly rugoreticulate interspaces; scape, when laid back, exceeding the midlength of head by one-fifth of its length; lateral sides of promesonotum distinctly foveolate without additional sparse and indistinct rugulae; inner hypostomal teeth distinct, large, closely spaced, triangular, with rounded apex directed upward; outer hypostomal teeth lobe-like, approximately the same height and width as inner teeth; inner and outer hypostomal teeth closely spaced and not connected by concavity; base of first gastral tergite shagreened. Minor workers.HL < 0.45 mm and WL < 0.5 mm, scape, when laid back, surpassing the posterior head margin by one-fifth of its length; propodeal spines reduced to small tubercles; head relatively rectangular; body yellowish brown; lateral sides of frons smooth; vertex with transverse, sparse, and moderately thick, short rugulae; mesosoma smooth.

Major workers. Measurements (N = 1): HL: 0.86; HW: 0.74; SL: 0.45; EL: 0.1; WL: 0.7; PSL: 0.09; MTL: 0.38; PNW: 0.39; PTW: 0.12; PPW: 0.3; CI: 115.3; SI: 60.3; PSLI: 10.5; PPI: 40.4; PNI: 51.9; MTI: 51.1.

Head. In full-face view elongate, not widening posteriorly, with anterior and posterior sides slightly convex (Fig. 26B). In lateral view sub-oval; ventral and dorsal faces convex; inner hypostomal teeth visible. Sides of the head with moderately dense, moderately short, suberect to erect pilosity; whole head with dense, long, decumbent to erect pilosity. Medial part of frons with thick, longitudinal, and dense rugae and distinctly rugulate interspaces, rugae more irregular and with denser sculpture of interspaces on posteromedial part; lateral sides with thick, dense and longitudinal rugae with distinctly rugofoveolate interspaces, rugae more irregular on posterolateral parts. Occipital lobes with dense, irregular rugae and distinctly rugoreticulate interspaces. Area posterolateral from eyes with dense rugofoveolae. Gena with relatively sparse and thick, longitudinal rugae and indistinctly rugoreticulate interspaces. 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 one-fifth of its length; pilosity subdecumbent to erect (Fig. 26B, D). Inner hypostomal teeth distinct, large, closely spaced, triangular, with rounded apex directed upward; outer hypostomal teeth lobe-like, approximately the same height and width as inner teeth; inner and outer hypostomal teeth closely spaced and not connected by concavity (Fig. 63H). Mesosoma. In lateral view, promesonotum short, angular, and moderately high, posterior mesonotum moderately steep, mesonotal process very indistinct, tubercle-like; promesonotal groove absent; metanotal groove absent; propodeal spines very small, with wide base and acute apex; humeral area produced (Fig. 26D). Surface shiny and distinctly foveolate; katepisternum with sparser foveolae. Pilosity sparse, moderately long, and erect (Fig. 26D, F). Petiole. Shiny with dense foveolae; node finely foveolate, triangular, with rounded and thin apex, in rear view node dorsoventrally concave; pilosity moderately sparse and erect (Fig. 26D, F). Postpetiole. Shiny and foveolate; dorsum with reduced sculpture; in dorsal view oval, lateral margins medially with two distinct dentate projections; pilosity long, moderately sparse, and erect (Fig. 26D, F). Gaster. Shiny and smooth with shagreened base; pilosity moderately dense, moderately short, and erect (Fig. 26D, F). Colour. Ochreous with yellow legs and antenna (Fig. 26D, F).

Minor workers. Measurements (N = 1): HL: 0.44; HW: 0.39; SL: 0.39; EL: 0.1; WL: 0.48; PSL: 0.05; MTL: 0.3; PNW: 0.25; PTW: 0.06; PPW: 0.11; CI: 112.8; SI: 98.7; PSLI: 10.9; PPI: 48.7; PNI: 65.0; MTI: 77.0.

Head. Cephalic margin slightly concave (Fig. 26A). Pilosity relatively sparse, moderately long, decumbent to subdecumbent. Sculpture shiny and smooth; vertex with transverse, sparse, and moderately thick, short 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, exceeding the posterior head margin by one-fifth of its length; pilosity dense, subdecumbent to erect (Fig. 26A, C). Mesosoma. In lateral view, promesonotum moderately high and short, box-like; promesonotal groove absent; metanotal groove distinct; propodeal spines reduced to small tubercles (Fig. 26C). Sculpture shiny and smooth. Pilosity sparse, moderately long, and erect (Fig. 26C, E). Gaster. With sparse, erect pilosity (Fig. 26C, E). Colour. Yellow (Fig. 26C, E).

From the type locality.

The species was collected at 272 m in elevation, in tropical dry forest. Nest was located in rotten log.

Pheidole beanka 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), elongate and not widening posteriorly head in major workers, and minor workers with predominantly smooth and relatively rectangular head and yellow to brown body colouration. The group includes five species: P. flavominuta sp. nov., P. nitidobruna sp. nov., P. mikros sp. nov., and P. beanka sp. nov. Pheidole beanka sp. nov., described from Réserve forestière Beanka, is the only member of this group known from the Mahajanga and its distribution doesn’t overlap with the remaining four taxa. However, morphology of P. beanka sp. nov. is most similar to P. mikros sp. nov., which is distributed on the southernmost part of the Antsiranana prefecture. Major workers of Pheidole beanka sp. nov. differ from P. mikros sp. nov. in the combination of the following characters: medial part of frons with distinctly rugulate interspaces and very small propodeal spines; minor workers can be separated based on smooth lateral sides of frons and mesosoma, yellow body, and propodeal spines reduced to small tubercles.