Pheidole trichotos

The species was collected between 74-1657 m in elevation, in montane rainforest and in gardens. Nests were located in rotten logs, rotten tree stumps, and dead twigs above ground.

Identification
Salata and Fisher (2020) - Pheidole trichotos can be grouped with species characterised by dark body colouration, ranging in major workers from brownish black to black and in minor workers from black to dark brown, with body entirely foveolate. The group consists of three sympatric species: Pheidole alina, P. trichotos, and Pheidole mainty. Pheidole alina and P. mainty are known from the northernmost part of the island. Major workers of P. trichotos differ from P. alina and P. mainty in medial part of frons with thick, interrupted, dense, and longitudinally irregular rugae with indistinctly to distinctly rugulate interspaces and shagreened base of first gastral tergite. Minor workers of P. trichotos differ from P. alina in smaller body size and brighter body colouration; from P. mainty in entirely foveolate head and mesosoma. Majors of P. trichotos can be also confused with major workers of parapatric Pheidole veteratrix and sympatric P. anomala P. trichotos can be separated from both of those taxa based on shagreened base of first gastral tergite and darker body colouration.

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Nomenclature

 * . Pheidole trichotos Salata & Fisher, 2020: 154, figs. 57A–F, 64O, 67G (w.) MADAGASCAR.

Worker
Major (N = 10): HL: 1.34-1.5 (1.39); HW: 1.26-1.45 (1.36); SL: 0.86-0.95 (0.89); EL: 0.18-0.21 (0.19); WL: 1.14-1.3 (1.21); PSL: 0.17-0.22 (0.21); MTL: 0.82-0.91 (0.86); PNW: 0.5-0.56 (0.52); PTW: 0.15-0.19 (0.17); PPW: 0.3-0.41 (0.35); CI: 99.9-107.5 (103.0); SI: 61.7-68.2 (65.6); PSLI: 12.8-16.4 (14.8); PPI: 42.2-57.2 (48.6); PNI: 35.2-41.8 (38.6); MTI: 61.4-67.4 (63.8).

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; inner hypostomal teeth visible. Sides of the head with very dense, long, suberect to erect pilosity; whole head with dense, long, decumbent to erect pilosity. Medial part of frons with thick, interrupted, dense, and longitudinally irregular rugae with indistinctly to distinctly rugulate interspaces; lateral sides of frons with denser, thick, and irregular rugae, interspaces with dense and distinct rugulae. Occipital lobes with irregular and sparser rugae and indistinctly rugulate to smooth interspaces. Area posterolateral from eyes with dense, thick, longitudinal rugae with distinctly rugulate interspaces, sculpture fading posteriorly. Gena with relatively sparse, thick, and longitudinal rugae and 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. Inner hypostomal teeth distinct, large, and wide, closely spaced, triangular with apex directed slightly inward; outer hypostomal teeth lobe-like, narrower than and approximately as high as inner teeth, apex directed upward; inner and outer hypostomal teeth closely spaced and not connected by concavity. Mesosoma. In lateral view, promesonotum short, angular, and moderately low, posterior mesonotum moderately steep, mesonotal process indistinct, tubercle-like; promesonotal groove absent; metanotal groove present; propodeal spines moderately long, relatively wide, and with acute apex; humeral area weakly produced. Surface shiny and rugofoveolate; katepisternum with reduced sculpture and sometimes with smooth notch. Pilosity moderately dense, long, and erect. 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. Postpetiole. Shiny and foveolate; dorsum with reduced sculpture; in dorsal view oval, lateral margins medially with two small and dentate projections; pilosity long, moderately sparse, and erect. Gaster. Shiny with slightly shagreened base; pilosity moderately dense, long, and erect. Colour. Yellow to blackish brown, antenna and legs yellowish.

The following characters are found in most Pheidole sikorae species-group majors in Madagascar (Salata and Fisher 2020b). These characters also occur in , except for any differences noted in the paragraph above. Dorsal face of head in lateral view not depressed posteriorly; 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 absent; promesonotum strongly convex, well above the level of propodeum; petiolar peduncle with small horizontal lobes on its basal part; postpetiole short with slightly convex dorsum; petiolar peduncle without horizontal lobes on its basal part; body unicolourous.

Minor (N = 10): HL: 0.67-0.76 (0.72); HW: 0.55-0.61 (0.57); SL: 0.83-0.92 (0.88); EL: 0.13-0.16 (0.14); WL: 0.89-1.01 (0.95); PSL: 0.1-0.14 (0.12); MTL: 0.67-0.77 (0.72); PNW: 0.38-0.42 (0.4); PTW: 0.06-0.11 (0.09); PPW: 0.17-0.18 (0.17); CI: 121.8-133.6 (125.9); SI: 144.0-158.5 (152.9); PSLI: 14.2-18.9 (16.7); PPI: 35.5-60.3 (53.5); PNI: 67.7-72.5 (70.1); MTI: 117.7-134.7 (125.0).

Head. Cephalic margin slightly convex. Pilosity relatively sparse, short, subdecumbent. Sculpture shiny and foveolate; median frons with short, indistinct and irregular rugulae; antennal sockets with few indistinct, curved outward rugae and foveolate interspaces. Clypeus foveolate; with median longitudinal carina absent; two lateral longitudinal carinae absent. Scape, when laid back, exceeding the posterior head margin by two-fifths of its length; pilosity dense, subdecumbent to erect. Mesosoma. In lateral view, promesonotum low and moderately long, arched; promesonotal groove indistinct; metanotal groove distinct; propodeal spines minute and triangular. Sculpture shiny and foveolate; katepisternum with sparser foveolae. Pilosity sparse, moderately long, and erect. Gaster. With sparse, erect pilosity. Colour. Yellow to black, legs and antenna yellowish.

The following characters are found in most Pheidole sikorae species-group minors in Madagascar (Salata and Fisher 2020b). These characters also occur in , except for any differences noted in the paragraph above. Antennal sockets shallow; frontal lobes absent; occipital carina 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, with node moderately low, triangular, and small, with few short, erect setae; petiolar peduncle with ventral face slightly convex; postpetiole smooth, short, low, and slightly convex, with few short, erect setae; gaster smooth and shiny; body unicolourous.

Type Material
Holotype. Madagascar. 1 major worker; Mahajanga; Region Sofia, Ampotsidia; -14.41592, 48.71118; alt. 1364 m; 11 Jan 2017; B. L. Fisher et al. leg.; montane rainforest, ex rotten log; BLF39812; CASENT0788058. Paratype. 1w.; same data as for holotype, CASENT0923258 (CASC).

Etymology
Greek for hairy in reference to dense setosity on lateral sides of head in major workers.