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Species: Pheidole williamsi   Wheeler, 1919 

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Taxonomic History (provided by Barry Bolton, 2019)

Pheidole williamsi Wheeler, 1919d: 267 (s.w.q.m.) ECUADOR (Galapagos Is). Neotropic. AntCat AntWiki HOL

Taxonomic history

Senior synonym of Pheidole seymourensis: Wilson, 2003A: 249.


  Geographic regions (According to curated Geolocale/Taxon lists):
    Americas: Ecuador
  Biogeographic regions (According to curated Bioregion/Taxon lists):

Distribution Notes:

Baltra, Daphne, Isabela, Santa Cruz, Seymour Norte, Santiago.

Taxonomic Treatment (provided by Plazi)

Treatment Citation: Wilson, E. O., 2003, Pheidole in the New World. A dominant, hyperdiverse ant genus., Cambridge, MA: Harvard University Press

Pheidole williamsi WheelerHNS

Pheidole williamsi WheelerHNS 1919d: 267. Syn.: Pheidole williamsi var. seymourensis WheelerHNS 1924b: 108, n. syn. types Mus. Comp. Zool. Harvard.

Etymology Named after Harrison Williams, leader of a Galapagos collecting expedition.

diagnosis A small, yellow member of the diligensHNS group, closest to crozieriHNS of Peru, but also with some similarities to vafellaHNS, as well as rufipilisHNS and the mostly South American species listed with rufipilisHNS (q.v.), differing from crozieriHNS as follows.

Major: dark yellow; pronotum in side view peaked in a blunt angular profile, and weakly bilobous in dorsal-oblique view; occiput weakly concave; anterior margin of pronotal dorsum carinulate; apex of petiolar node in side view tapering to a blunt point.

Minor: petiolar node in side view relatively low, and in rear view with dorsal border strongly convex.

Measurements (mm) Lectotype major: HW 1.04, HL 1.10, SL 0.74, EL 0.16, PW 0.52.

Paralectotype minor: HW 0.48 (approximately), HL 0.62, SL 0.66, EL 0.12, PW 0.30.

color Major: concolorous dark yellow.

Minor: body brownish yellow, appendages dark to medium yellow.

The Wheeler types may be faded; minors collected on Isla San Salvador in 1991 (P. Oromi) have light brown bodies.

range Known only from Isla Santa Cruz, Isla Seymour, and Isla San Salvador. An apparent endemic of the Galapagos Islands. The species appears to be rare.

Biology Males were collected with the lectotype series in November 1905.

Figure Upper: lectotype, major. Lower: paralectotype, minor. GALAPAGOS ISLANDS: Isla Santa Cruz. Scale bars = 1 mm.

Specimen Habitat Summary

Found most commonly in these microhabitats: 1 times fern.

Collected most commonly using these methods: 1 times En cebo de atún, 1 times Aspirator.

Elevations: collected from 850 - 1032 meters, 995 meters average

Type specimens: syntype of Pheidole williamsi: castype00444-01, castype00444-02, castype00444-03

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