Pheidole polymorpha

Collected in upland desert. Comment by Stefan Cover (personal communication): “A very interesting beast; it is like Pheidole artemisia (=Pheidole pilifera) or Pheidole cavigenis on steroids.” (Wilson 2003)

Identification
See the description in the nomenclature section.

Distribution
Known only from the type locality and from Chapulco, Puebla, Mexico. (Wilson 2003)

Distribution based on Regional Taxon Lists
Neotropical Region: Mexico.

Nomenclature

 *  polymorpha. Pheidole polymorpha Wilson, 2003: 592, figs. (s.w.) MEXICO.

Description
DIAGNOSIS A member of the “pilifera complex” of the larger pilifera group, comprising Pheidole calens, Pheidole californica, Pheidole carrolli, Pheidole cavigenis, Pheidole clementensis, Pheidole creightoni, Pheidole hoplitica, Pheidole littoralis, Pheidole micula, Pheidole pilifera, Pheidole polymorpha, Pheidole rugulosa, Pheidole senex, Pheidole soritis, Pheidole tepicana and Pheidole torosa, which complex is distinguished by the following traits. Major: dorsal head surface extensively sculptured; occipital lobes transversely rugulose (or, in carrolli smooth, in littoralis foveate, and in micula and soritis carinulate); postpetiole from above diamond-shaped, trapezoidal, or spinose. Minor: eye medium-sized to large.

P. polymorpha is distinguished within the complex by the following combination of traits. Worker caste trimorphic, with major, supermajor, and minor.

Major: humerus very pronounced and subtriangular in shape in dorsal-oblique view; propodeal spines stout and vertical to the basal propodeal face; postpetiole from above with sharp right-angular margins; pilosity, long and dense.

Minor: all of mesosoma and almost all of the dorsal head surface foveolate and opaque.

Both major and minor: dorsal margin of petiole seen from behind strongly convex.

MEASUREMENTS (mm) Holotype major: HW 1.34, HL 1.46, SL 0.62, EL 0.20, PW 0.60. Paratype minor: HW 0.54, HL 0.60, SL 0.56, EL 0.14, PW 0.38.

COLOR Major and minor: brownish yellow.



'''Figure. Upper: holotype, major; partial head in full-face view of paratype, supermajor. Lower: paratype, minor. Scale bars = 1 mm.'''

Type Material
From Wilson (2003): MEXICO: Highway 57, km 127, Estado México, col. Cornell University Field Party, 1965.

Etymology
Gr polymorpha, many forms, referring to the coexistence of major and supermajor castes.

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
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133
 * Wilson, E.O. 2003. Pheidole in the New World: A Dominant, Hyperdiverse Genus. Harvard University Press