Pheidole walkeri

Longino, J. T., 2009, Additions to the taxonomy of New World Pheidole (Hymenoptera: Formicidae)., Zootaxa 2181, pp. 1-90 : 86-88

Pheidole walkeri

Pheidole walkeri Mann, 1922: 27 , fig. 13. Lectotype major worker (here designated, as labeled by Wilson 2003) and associated paralectotype minor worker: Honduras, San Juan Pueblo (Mann) [ USNM] ( MCZ major worker specimens from type series examined).

Pheidole arietans Wilson, 2003: 657 , figs. 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). New synonymy.

Pheidole glyphoderma Wilson, 2003: 697 , figs. 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). New synonymy.

Pheidole triumbonata Wilson, 2003: 771 , figs. 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). New synonymy.

Geographic Range

Costa Rica, Honduras, Mexico (Chiapas).

Biology

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.

Comments

Pheidole walkeri shares many characters with P. 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, and the following forms 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.

Pheidole arietans , lowland Costa Rica: minor worker with face completely smooth and shining, nearly black; katepisternum mostly smooth and shining, with foveolation restricted to ventral and posterior margins. Major worker with clypeus flat, smooth, matte, with only a trace of medial horn; sculpture on face posterior to clypeus a short series of arcing rugae that meet medially, followed by transverse rugulae; setae on sides of head suberect; medial portion of side of pronotum, almost entire katepisternum, and lateral propodeum anterior to spiracle smooth, shining, highly polished. This form occurs in the Costa Rican lowlands, from La Selva Biological Station to 500m on the Barva Transect; in the Penas Blancas Valley at both Poco Sol station and Refugio Eladio, at 800m; and on the lower slope of Volcan Arenal at 700m.

Highland Barva Transect form, Costa Rica: minor worker face completely foveolate; somewhat lighter brown; katepisternum more extensively foveolate, with small shiny patch anterodorsally or almost entirely foveolate. Major worker with clypeus as in arietans ; sculpture on face posterior to clypeus like arietans , but anterior arcing rugae may be replaced by irregular mesh of rugae; setae on sides of head suberect, like arietans ; side of pronotum with more extensive faint rugulae crossing medial area, katepisternum with larger patch of foveolation ventrally, lateral propodeum anterior to spiracle more foveolate compared to arietans . This form occurs in higher elevation forest, on the Barva transect, 600-1100m.

Penas Blancas form, Costa Rica: minor worker face faintly and irregularly rugulose foveolate (intermediate between entirely shiny face of arietans and fully foveolate face of highland Barva form and P. glyphoderma ); somewhat lighter brown; sculpture on side of mesosoma similar to upland Barva form. Major worker like upland Barva form, with sculpture on side of mesosoma somewhat intermediate between that form and arietans . This form is known only from Refugio Eladio in the Penas Blancas valley, at 800m, where it appears to be sympatric with P. arietans .

Pheidole glyphoderma , highland Costa Rica: minor worker same as highland Barva form. Major worker with clypeus more concave, sublucid instead of matte, with scattered faint longitudinal rugulae; medial face posterior to clypeus with entirely longitudinal rugulae that fan outward onto posterior lobes; setae on sides of head lanose, fully appressed; lateral pronotum with faint linear rugulae, katepisternum mostly smooth and shining, lateral propodeum anterior to spiracle foveolate. This form is known only from Monteverde cloud forest, at 1500m. It is rare in Monteverde, known from only two separate collections in spite of abundant collecting there.

Pheidole triumbonata , southern Mexico: minor worker same as glyphoderma . Major worker with clypeus more concave, sublucid like glyphoderma , medial clypeal carina more developed, extending almost entire length of clypeus on most specimens (very short and nearly obsolete in one); sculpture on face posterior to clypeus like arietans on most specimens, but one specimen with entirely longitudinal rugulae like glyphoderma ; setae on sides of head suberect; sculpture on side of mesosoma like glyphoderma . This form is known from the type locality in Veracruz and two mid-elevation (500-1000m) sites in northern Chiapas.

Pheidole walkeri , lowland Honduras: minor workers of the type series were not examined, but from the illustrations in Wilson (2003) they are like P. arietans . Major worker with clypeus sublucid, medial clypeal carina moderately developed on one specimen, nearly obsolete on another; medial face posterior to clypeus with entirely longitudinal rugulae that fan outward onto posterior lobes; setae on sides of head subdecumbent.