Pheidole diakritos

The species was collected at elevation between 360–865 m, in rainforest, and in montane rainforest. Nesting preferences are unknown.

Identification
Salata and Fisher (2020) - The lone member of the Pheidole diakritos species group. Major Large species: HL: 1.67-1.91 (1.75), HW: 1.66-1.86 (1.71), WL: 1.23-1.3 (1.27); head in full-face view rectangular; in lateral view sub-rectangular with visible inner hypostomal teeth; antennal scrobes absent; sides of the head with dense, relatively long, erect pilosity; antennal sockets deep; frontal lobes distinct and lobe-like; inner hypostomal teeth distinct, closely spaced, triangular, with rounded apex and base slightly wider than apex; outer hypostomal teeth absent. Minor Head shiny, with sparse, thick, irregular rugae, interspaces smooth or rugulose; frontal lobes present; antennal sockets deep; propodeal spines long and thin (PSL: 0.17-0.21 (0.19)).

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Worker
Minor

Nomenclature

 *  diakritos. Pheidole diakritos Salata & Fisher, 2020: 18, figs. 12A–F, 84M, 86M (w.) MADAGASCAR.

Worker
Major (N = 5): HL: 1.67-1.91 (1.75); HW: 1.66-1.86 (1.71); SL: 0.8-0.87 (0.85); EL: 0.15-0.16 (0.155); WL: 1.23-1.3 (1.27); PSL: 0.27-0.3 (0.28); MTL: 0.78-0.87 (0.81); PNW: 0.65-0.74 (0.69); PTW: 0.16-0.2 (0.17); PPW: 0.42-0.54 (0.46); CI: 97.1-99.4 (98.3); SI: 46.7-51.6 (48.9); PSLI: 14.8-17.7 (16.3); PPI: 36.1-39.8 (37.7); PNI: 38.9-42.8 (40.3); MTI: 46.9-47.8 (47.2).

Head. In full-face view rectangular, anterior of eyes relatively straight, posterior of eyes slightly convex. In lateral view sub-rectangular; ventral and dorsal faces relatively flat; inner hypostomal teeth visible. Sides of the head with dense, relatively long, erect pilosity; whole head with moderately dense, long, suberect to erect pilosity. Antennal scrobes absent. Antennal sockets deep, smooth, or with a few rugae. Frontal lobes distinct and lobe-like. Occipital lobes with thick, sparse rugae; sculpture slightly weakening posteriorly. Whole head shiny, with sparse, thick, irregular rugae, interspaces smooth. Clypeus shiny, with a few longitudinal rugae; median notch present, wide, and shallow. Scape, when laid back, just reaching the midlength of head; pilosity decumbent to erect. Inner hypostomal teeth distinct, closely spaced, triangular, with rounded apex and base slightly wider than apex; outer hypostomal teeth absent. Mesosoma. In lateral view, promesonotum short, angular, and low, posterior mesonotum convex, with low tubercle-like projection; promesonotal groove absent; metanotal groove indistinct; propodeal spines long, massive basally, with acute apex; humeral area with short, triangular tubercles. Surface shiny, with thick, dense rugoreticulation, sculpture slightly weakening on dorsum. Pilosity moderately dense, long and erect. Petiole. Shiny, foveolate; peduncle relatively long, without horizontal lobes on its basal part; node, low and narrow, with flat apex, in rear view node dorsoventrally depressed; pilosity moderately dense and erect. Postpetiole. Foveolate; in dorsal view sides with short, acute, and triangular projections; pilosity long, moderately sparse and erect. Gaster. Shagreened on the whole surface; pilosity moderately dense, very long and erect. Colour. Unicolourous, dark brown.

The following apply to all Pheidole majors of Madagascar, unless stated otherwise above. Antennal sockets shallow; frontal lobes absent; head in full-face view with distinct median concavity; antenna 12-segmented, with 3-segmented club; masticatory margin of mandible with large, stout apical and preapical teeth, followed by a long diastema and then a short and crenulate tooth just before the rounded basal angle; outer surface of mandible mostly smooth and shining, sometimes with weak and sparse foveolae; antennal scrobes present; promesonotum strongly convex, well above the level of propodeum; postpetiole short with slightly convex dorsum; ventral process absent.

Minor (N = 10): HL: 0.68-0.78 (0.73); HW: 0.59-0.68 (0.64); SL: 0.73-0.83 (0.81); EL: 0.07-0.12 (0.1); WL: 0.89-1.04 (0.98); PSL: 0.17-0.21 (0.19); MTL: 0.56-0.66 (0.62); PNW: 0.44-0.52 (0.49); PTW: 0.08-0.13 (0.1); PPW: 0.12-0.19 (0.16); CI: 85.3-90.2 (87.8); SI: 121.9-129.7 (125.3); PSLI: 25.1-28.7 (26.4); PPI: 59.1-69.3 (64.6); PNI: 73.9-78.4 (76.0); MTI: 92.6-103.0 (97.1).

Head. Occipital margin indistinctly concave; occipital carina indistinct, weakly developed. Pilosity sparse, long, suberect to erect; antennal sockets deep, smooth or with a few rugae; frontal lobes distinct and lobe-like. Whole head shiny, with sparse, thick, irregular rugae, interspaces smooth or with rugulae. Clypeus rugulose and shiny; median longitudinal carina absent; two lateral longitudinal carinae absent. Scape, when laid back, surpassing posterior head margin by two-fifths of its length; pilosity suberect to erect. Mesosoma. In lateral view, promesonotum convex; promesonotal groove present; metanotal groove present; humeral area with short triangular tubercles; propodeal spines moderately long, with base almost as wide as apex, apex acute. Pronotum and mesonotum with thick, dense rugoreticulation, sculpture slightly weakening on dorsum; katepisternum, anepisternum, and propodeum foveolate. Pilosity sparse, long, and erect. Petiole. Shiny; peduncle foveolate, moderately long and thin; node smooth, low, bulge-like; with few long, erect setae. Postpetiole. Sometimes partially foveolate; moderately short, low and slightly convex; with few long, erect setae at the anterior edge. Gaster. Pilosity sparse and erect. Colour. Brown to dark brown, legs brighter. The following apply to all Pheidole minors of Madagascar, unless stated otherwise above. Antennal sockets shallow; frontal lobes absent; head in full-face view oval, posterior and anterior of eyes convex; antenna 12-segmented, with 3-segmented club; humeral area not developed; clypeus smooth and shiny; its anterior margin regularly convex; promesonotum well above the level of propodeum; petiole smooth; petiole with node moderately low, triangular and small postpetiole smooth; gaster smooth and shiny.

Type Material
Holotype. Madagascar. 1 major worker; Toamasina; Ankerana; ; alt. 750 m; 21 Jan 2012; B.L. Fisher et al. leg.; CASENT0275436. Paratype. Madagascar. 1 w.; Toamasina; Ankerana; alt. 725 m; 16 Jan 2012; B.L. Fisher et al. leg.; BLF27931, CASENT0275480 (CASC).

Etymology
Greek for distinct, in reference to its being the only known species with distinct frontal lobes and deep antennal sockets.