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.

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
- as reported in Wilson (2003)

Type Locality Information
GALÁPAGOS ISLANDS: Isla Santa Cruz. (Wilson 2003)

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