Pheidole walkeri

This species is found in or near primary wet forest. Workers recruit to baits and may have seed caches in their nests. Nests are in dead wood, dead branches, and live stems. Nests have been found in live stems of Myriocarpa (Urticaceae) along streams and in internodes of Cecropia saplings. Colonies may be polydomous (e.g., in multiple separate internodes of Cecropia saplings). Nests occur from ground level to the canopy. (Longino 2009)

Identification
See the description in the nomenclature section.

Distribution based on Regional Taxon Lists
Neotropical Region: Belize, Costa Rica, Guatemala, Honduras, Mexico, Nicaragua.

Worker
Minor

Nomenclature

 *  walkeri. Pheidole walkeri Mann, 1922: 27, fig. 13 (s.w.) HONDURAS. See also: Wilson, 2003: 777. Senior synonym of arietans, glyphoderma, triumbonata: Longino, 2009: 86.
 * arietans. Pheidole arietans Wilson, 2003: 657, figs. (s.w.) COSTA RICA. Junior synonym of walkeri: Longino, 2009: 86.
 * glyphoderma. Pheidole glyphoderma Wilson, 2003: 697, figs. (s.w.) COSTA RICA. Junior synonym of walkeri: Longino, 2009: 86.
 * triumbonata. Pheidole triumbonata Wilson, 2003: 771, figs. (s.w.) MEXICO. Junior synonym of walkeri: Longino, 2009: 86.

Longino (2009) - Pheidole walkeri shares many characters with Pheidole rhinoceros. The minor workers are nearly indistinguishable. The majors have the clypeus flat or slightly concave, but nearly always with a trace of the medial horn that is prominent in rhinoceros. The majors all have the dorsal surface of the mandible with very short, fully appressed setae only, no large piligerous puncta, and the base of the mandible has roughened sculpture that extends a variable distance onto the dorsal surface. Pheidole walkeri may well be a complex of multiple cryptic species; the synonymized and other distinctive forms from specific locales can be recognized. Although the forms exhibit discordant character variation and are not cleanly separable, there is the potential for six or more cryptic species.

Description
From Wilson (2003): DIAGNOSIS A very distinctive member of the tristis group, with clypeal structure in early stage of phragmosis.

Major: lateral wings of clypeus projecting forward, creating a semi-phragmotic head; no hairs on clypeus, also an apparent semiphragmotic trait; frontal lobes projecting and subangulate in side view; carinulae originating in frontal lobes tum posteriorly outward to reach the sides of the head; rugoreticulum extends from eye to rear of antennal fossa on each side of head; margins of pronotum and dorsum of propodeum carinulate; postpetiole from above elliptical.

Minor: occiput narrowed slightly, nuchal collar absent; promesonotal dorsum semicircular in side view, subangulate in dorsal-oblique view; propodeal spines reduced to dentic1es.

MEASUREMENTS (mm) Lectotype major: HW 1.26, HL 1.38, SL 0.64, EL 0.14, PW 0.68. Paralectotype minor: HW 0.54, HL 0.60, SL 0.56, EL 0.12, PW 0.34.

COLOR Major: body medium reddish brown except for anterior half of head, which is dark reddish brown; appendages light reddish brown.

Minor: body medium reddish brown, appendages light reddish brown.



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

Type Material
Longino (2009):

Lectotype major worker (here designated, as labeled by Wilson 2003) and associated paralectotype minor worker: Honduras, San Juan Pueblo (Mann) ( major worker specimens from type series examined).

Pheidole arietans Holotype major worker and associated paratype minor worker: Costa Rica, Heredia, La Selva Biological Station, 25 Mar 1988, mature rainforest, hollow rotten stick, seeds present (Cover, Moffett, Tobin) MCZ (examined).

Pheidole glyphoderma Holotype major and associated paratype minor worker: Costa Rica, Puntarenas, Monteverde, 1500m, 25 May 1979, at sugar bait (P. S. Ward #3528-3) MCZ (examined).

Pheidole triumbonata Holotype major and associated paratype minor worker: Mexico, Veracruz, 2mi W Fortin de las Flores, 3300', 6 Jan 1973, nest under bark (R. J. & A. B. Hamton) MCZ (image examined).

Etymology
Eponymous. (Wilson 2003)

References based on Global Ant Biodiversity Informatics

 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Longino J. T. 2009. Additions to the taxonomy of New World Pheidole (Hymenoptera: Formicidae). Zootaxa 2181: 1-90.
 * Longino J. T. L., and M. G. Branstetter. 2018. The truncated bell: an enigmatic but pervasive elevational diversity pattern in Middle American ants. Ecography 41: 1-12.
 * Smith M. A., W. Hallwachs, D. H. Janzen. 2014. Diversity and phylogenetic community structure of ants along a Costa Rican elevational gradient. Ecography 37(8): 720-731.
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133