Pheidole wilsoni

Pheidole wilsoni has a widespread distribution across the Fiji island archipelago and was collected on most of the sampled islands, except Beqa and Koro. It seems to be an ecologically versatile species and was collected from leaf litter, nesting under stones, in sticks, rotten logs, in ant-plants and under moss in trees. Pheidole wilsoni can be found in several forest types, from primary rainforest to disturbed, logged, and fragmented forest, and occurs in elevations between 100 and 1050m. (Fisher et al. 2016)

Identification
Fisher et al. (2016) - knowlesi group: Major worker: moderately large (WL 0.87–0.97); head in profile weakly impressed between frontal area and posterolateral lobes; frontal carina sharply defined, scrobe posteriorly bordered by transverse to arcuate rugulae; rugulae on posterior third of head usually branching. Minor worker: head dorsum punctate, punctures medially partly effaced, pronotum and head venter smooth to superficially punctate; promesonotal outline in profile flatly convex, posterior declivity declining evenly. Queen: moderately large (WL 1.40–1.48), with longer legs (FI 82–86); clypeus with median notch; median hypostomal tooth distinctly smaller than submedian teeth; rugulae on mesosoma dorsum usually reaching anterior margin of scutum; gaster anterodorsally, near postpetiole, rugopunctate.

Pheidole wilsoni is phylogenetically and morphologically closely related to Pheidole knowlesi and Pheidole ululevu and the characters to distinguish them are listed in the diagnosis and discussed in the other two species. As in the other species in this group, with the possible exception of Pheidole kava, the major workers of P. wilsoni show a notable variation in total head size when viewed in proportion to total body size, with the larger specimens often having more robustly developed posterolateral lobes and thus a more elongate head shape.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Fiji.

Nomenclature

 *  wilsoni. Pheidole wilsoni Mann, 1921: 433 (s.w.) FIJI IS.

Worker
Fisher et al. (2016) - Major (n = 7): HW 1.02–1.19 (1.15), HL 1.10–1.28 (1.21), SL 0.61–0.65 (0.63), MDL 0.55–0.65 (0.63), EL 0.14–0.18 (0.15), WL 0.87–0.97 (0.91), PNW 0.53–0.55 (0.54), PTL 0.35–0.43 (0.39), PPL 0.17–0.20 (0.19), PTH 0.21–0.24 (0.23), PPH 0.19–0.22 (0.20), PTW 0.15–0.18 (0.17), PPW 0.26–0.37 (0.33), PSL 0.15–0.20 (0.18), MFL 0.75–0.82 (0.78), MTL 0.51–0.58 (0.54), CI 93–98 (94), SI 51–62 (55), MDI 52–56 (54), EI 12–17 (13), FI 63–80 (68), PpI 48–69 (62), LPpI 89–95 (92), DPpI 153–195 (178), PpWI 178–211 (196), PpHI 85–93 (89). Head and mesosoma with weakly to superficially punctate ground sculpture. Posterolateral lobes with scarce punctures and few short, superficial rugulae present. Dorsum of promesonotum with transverse rugulae. Petiole and postpetiole laterally and ventrally superficially punctate, dorsally smooth and shiny. Gaster smooth and shiny. Head subrectangular, sides convex and curved towards posterior head corners, posteriorly about as wide as anteriorly or slightly narrower. Mandibles and clypeus smooth, anterior margin with shallow median notch. Antennal socket situated in excavated pit, frontal lobes translucent. In profile view dorsal outline of head shallowly impressed between frons and posterolateral lobes. Small median tooth on hypostomal margin flanked by comparatively large submedian teeth. Moderately well-developed longitudinal rugae on frons ending before posterior head margin and posterolateral lobes. Frontal carina sharply defined and raised, bordering whole length of scrobe, reaching posterior end of scapes when in repose and reaching about 3/4 towards posterior head margin. Scrobe usually well-defined and wide. Scape length more than 1/2 of head width (SI 55–67), slightly surpassing anterior 2/3 of head, with decumbent pilosity and longer erect hairs along outer edge. Promesonotum in profile convex with steep, angulate posterior declivity. Metanotal groove not or very shallowly impressed. Propodeum in profile slightly higher than long, its dorsal face shorter than posterior declivity. Spines about as long as distance between their bases. In dorsal view pronotal humeri not projecting laterally. Metatibia pilosity mostly decumbent with subdecumbent longer hairs along outer edge. Postpetiole laterally with short processes, ventrally superficially punctate, and dorsally smooth and shiny. Standing hairs abundant, moderately long and flexuous, shorter pilosity decumbent to subdecumbent. Colour dark brown, mandibles, antennae and legs brown to apically light brown.

Minor (n = 7): HW 0.48–0.55 (0.52), HL 0.53–0.62 (0.58), SL 0.55–0.65 (0.61), MDL 0.33–0.40 (0.36), EL 0.11–0.13 (0.12), WL 0.64–0.79 (0.71), PNW 0.32–0.37 (0.35), PTL 0.24–0.29 (0.26), PPL 0.10–0.13 (0.12), PTH 0.13–0.15 (0.14), PPH 0.11–0.13 (0.12), PTW 0.08–0.12 (0.10), PPW 0.13–0.17 (0.15), PSL 0.09–0.13 (0.11), MFL 0.57–0.66 (0.62), MTL 0.40–0.48 (0.45), CI 86–91 (89), SI 113–120 (118), MDI 66–74 (69), EI 22–25 (23), FI 115–122 (120), PpI 39–45 (42), LPpI 86–108 (97), DPpI 113–150 (128), PpWI 131–160 (143), PpHI 79–83 (82). Head, mesonotum, lateral propodeum, and lateral petiole punctate to weakly punctate. Punctures on sides of face stronger and often overlain with weak, irregular rugulae. Head venter, majority of promesonotum, dorsal petiole and postpetiole, and gaster smooth and shiny. Head shape oval, with strongly convex sides and moderately wide, medially weakly concave posterior margin, and corners rounded. Mandibles smooth and clypeus smooth with short carinae anteriorly or laterally. Scapes surpassing posterior head margin by length of preapical antennal segment, pilosity subdecumbent with few suberect hairs along outer edge. Promesonotal outline in profile flatly convex, with evenly oblique posterior declivity. Metanotal groove relatively shallow, crossribs weakly developed to inconspicuous. Propodeum about as high as long to slightly lower. Spines curved forward, relatively long-spinose and acute, shorter than distance between their bases. Promesonotum dorsum often with faint traces of short, transverse rugulae and superficial microsculpture. Metatibia pilosity decumbent on inner edge and subdecumbent along outer edge. Postpetiole lower than petiole (PpHI 79–83), about as long as high (LPpI 86–108), in dorsal view distinctly wider than long (DPpI 113–150). Standing hairs on head and mesosoma mostly suberect, moderately long and abundant, slender, several hairs inclined in opposing directions. Shorter pilosity very fine, mostly subdecumbent. Colour brown to dark brown, mandibles, antennal funiculus, and legs lighter colored.

Queen
Fisher et al. (2016) - (n = 3): HW 1.03–1.08 (1.05), HL 0.95–1.00 (0.97), SL 0.66–0.71 (0.68), MDL 0.55–0.61 (0.58), EL 0.27–0.28 (0.27), WL 1.40–1.48 (1.43), PNW 1.00–1.03 (1.02), PTL 0.45–0.57 (0.51), PPL 0.25–0.28 (0.26), PTH 0.36–0.38 (0.37), PPH 0.34–0.37 (0.35), PTW 0.30–0.33 (0.32), PPW 0.59–0.62 (0.61), PSL 0.26–0.28 (0.27), MFL 0.85–0.89 (0.88), MTL 0.58–0.63 (0.61), CI 108, SI 63–68 (65), MDI 53–56 (55), EI 25–27 (26), FI 82–86 (84), PSLI 24–27 (25), LPpI 71–77 (74), DPpI 221–248 (235), PpWI 179–207 (193), PpHI 94–97 (95). Head slightly wider than long (CI 108), anterior margin of clypeus with median notch. Scapes moderately short (SI 63–68), pilosity decumbent with longer suberect hairs along outer edge. Eyes relatively small (EI 25–27). Frons smooth, scrobes and sides of head weakly punctate, longitudinal rugae reaching posterior head margin, area above scrobes weakly reticulate, ventral side of head rugulose. Hypostomal margin with small median tooth and two distinctly larger submedian teeth. Oblique carinae on scutum usually reaching anterior margin in anterodorsal view. Lateropronotum obliquely rugulose and anepisternum dorsolaterally sometimes weakly rugopunctate. Propodeum laterally with abundant, well-defined curved rugulae, dorsally usually effaced. Remainder of mesosoma smooth. Petiole ventrally with convex bulge, with several transverse raised rugae present on its surface. Anterodorsal face of petiole smooth to punctate and posterior face transversally rugulose. Postpetiole in profile with very convex and punctate ventral process, in dorsal view anteriorly rugopunctate and posteriorly smooth, wide (PpWI 179–207), with lateral corners extended into blunt processes. Gaster mostly smooth, but anteriorly near postpetiole, rugopunctate. Standing hairs relatively abundant, of varying lengths, suberect to subdecumbent, yellow. Colour brown or dark brown, anterior of head, mandibles, antennae and legs lighter coloured to yellow.

Type Material
Fisher et al. (2016) - FIJI, Kadavu, Vanua Ava (W. M. Mann). Syntypes: 3 minor workers, 3 major workers (USNM, not examined); (MCZC 8696, not examined).

References based on Global Ant Biodiversity Informatics

 * Dlussky G.M. 1994. Zoogeography of southwestern Oceania. Zhivotnoe naselenie ostrovov Iugo-Zapadnoi Okeanii ekologo-geograficheskie issledovanii 48-93.
 * Fischer G., E. M. Sarnat, and E. P. Economo. 2016. Revision and microtomography of the Pheidole knowlesi Group, an endemic ant radiation in Fiji (Hymenoptera, Formicidae, Myrmicinae). PLoS ONE 11(7): e0158544. doi:10.1371/journal.pone.0158544
 * Mann W. M. 1921. The ants of the Fiji Islands. Bull. Mus. Comp. Zool. 64: 401-499.
 * Sarnat Eli M. 2009. The Ants [Hymenoptera: Formicdiae] of Fiji: Systematics, Biogeography and Conservation of an Island Arc Fauna. 80-252
 * Ward D. 2008. Ecological partitioning and invasive ants (Hymenoptera: Formicidae) in a tropical rain forest ant community from Fiji. Pacific Science 62(4): 473-482.
 * Ward, Darren F. and James K. Wetterer. 2006. Checklist of the Ants of Fiji. Fiji Arthropods III 85: 23-47.
 * Wheeler, William Morton.1935.Checklist of the Ants of Oceania.Occasional Papers 11(11): 3-56
 * Wilson E.O., and G.L. Hunt. 1967. Ant fauna of Futuna and Wallis islands, stepping stones to Polynesia. Pacific Insects 9(4): 563-584.
 * Wilson, Edward O. and George L. Hunt. 1967. Ant Fauna of Futuna and Wallis Islands, Stepping Stones To Polynesia. Pacific Insects. 9(4):563-584.
 * Wilson, Edward O. and Hunt, George L. Jr. 1967. Ant Fauna of Futuna and Wallis Islands, Stepping Stones to Polynesia. Pacific Insects. 9(4):563-584