Pheidole williamsi

Males were collected with the lectotype series in November 1905. (Wilson 2003)

Identification
See the description in the nomenclature section.

Distribution
Only known from the Known only from Isla Santa Cruz, Isla Seymour, and Isla San Salvador. An apparent endemic of the Galápagos Islands. The species appears to be rare. (Wilson 2003)

Distribution based on Regional Taxon Lists
Neotropical Region: Ecuador, Galapagos Islands.

Worker
Minor

Nomenclature

 *  williamsi. Pheidole williamsi Wheeler, W.M. 1919c: 267 (s.w.q.m.) ECUADOR (Galapagos Is). Senior synonym of seymourensis: Wilson, 2003: 249.
 * seymourensis. Pheidole williamsi var. seymourensis Wheeler, W.M. 1924a: 108 (s.w.) ECUADOR (Galapagos Is). Junior synonym of williamsi: Wilson, 2003: 249.

Description
From Wilson (2003): A small, yellow member of the diligens group, closest to Pheidole crozieri of Peru, but also with some similarities to Pheidole vafella, as well as Pheidole rufipilis and the mostly South American species listed with rufipilis (q.v.), differing from crozieri 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.



'''Figure. Upper: lectotype, major. Lower: paralectotype, minor. Scale bars = 1 mm.'''

Type Material
GALÁPAGOS ISLANDS: Isla Santa Cruz. - as reported in Wilson (2003)

Etymology
Named after Harrison Williams, leader of a Galápagos collecting expedition. (Wilson 2003)

References based on Global Ant Biodiversity Informatics

 * Clark, David B., Concepcion Guayasamin, Olga Pazmino, Cecilia Donoso, Yolanda Paez de Villacis. 1982. The Tramp Ant Wasmannia auropunctata. Biotropica. 14 (3):196-207.
 * Herrera H. W. 2013. CDF Checklist of Galapagos Ants - FCD Lista de especies de Hormigas Galápagos. In: Bungartz, F., Herrera, H., Jaramillo, P., Tirado, N., Jiménez-Uzcátegui, G., Ruiz, D., Guézou, A. & Ziemmeck, F. (eds.). Charles Darwin Foundation Galapagos Species Checklist - Lista de Especies de Galápagos de la Fundación Charles Darwin. Charles Darwin Foundation / Fundación Charles Darwin, Puerto Ayora, Galapagos: http://checklists.datazone.darwinfoundation.org/terrestrial-invertebrates/formicidae/ Last updated: 01 Mar 2013
 * Herrera H.W., and L. Roque-Albelo. 2007. Lista anotada de las hormigas de las Islas Galapagos, Ecuador. Fundación Charles Darwin. 13 pp
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Kusnezov N. 1963. Zoogeografia de las hormigas en sudamerica. Acta Zoologica Lilloana 19: 25-189
 * Kusnezov N. 1963. Zoogeografia de las hormigas en sudamerica. Acta Zoologica Lilloana 19: 25-190
 * Linsley E. G., and R. L. Usinger. 1966. Insects of the Galápagos Islands. Proc. Calif. Acad. Sci. (4) 33: 113-196.