Key to Pheidole perpusilla group

This worker key is based on: Wilson, E. O. 2003. Pheidole in the New World: A dominant, hyperdiverse ant genus. Harvard University Press, Cambridge, MA.

This is a compact group of Neotropical species of exceptionally small size. Although their body forms and caste systems are typical of Pheidole, the species are unique within the genus in possessing only 10 antennal segments instead of 11 or the usual 12, hence their occasional formal recognition as a discrete subgenus, Decapheidole. In fact, they have the overall traits of the flavens group, and the reduction in antennal segment number is probably a derived condition correlated with their overall reduced size. Known from Panama to Trinidad and Amazonian Brazil and Peru, members of the Pheidole perpusilla group are everywhere rare, or at least seldom collected.

1

Major: carinulae of dorsal surface of head extend at most over the anterior half of the head; forward half of the median strip of the first gastral tergite shagreened and opaque (Panama to Peru) . . . . . Pheidole zeteki

Major: carinulae cover all of the median half of the dorsal surface of the head, from the anterior edge ofthe frontal lobes to the occipital border; first gastral tergite smooth and shiny . . . . . 2

2

return to couplet #1

Major: region above (posterior to) the eye devoid of carinulae. Major and minor: propodeal spine in side view more than half as long as the basal face of the propodeum anterior to it (montane Ecuador) . . . . . Pheidole globularia

Major: region above (posterior to) the eye bears longitudinal carinulae. Major and minor: propodeal spine in side view one-fourth or less the length of the basal face of the propodeum anterior to it . . . . . 3

3

return to couplet #2

Major: mesosoma entirely smooth and shiny; in side view, profile of promesonotal dorsum forming a near-perfect arc of a circle; hairs of first gastral tergite sparse, as short as the propodeal spiracle is long, and mostly subappressed. Minor: entire body smooth and shiny, and its dorsal surface profile almost completely devoid of pilosity (Amazonian Peru) . . . . . Pheidole gemmula

Major: mesosoma entirely foveolate and opaque; profile of promesonotal dorsum flattened into a low convexity at its center; hairs of first gastral tergite abundant, much longer than the propodeal spiracle, and mostly sub erect to erect. Minor: all of dorsal surface of head and mesonotum foveolate and opaque, and all of dorsal surface profile of body with abundant pilosity (Panama to Amazonian Brazil) . . . . . Pheidole perpusilla

Pheidole perpusilla, Major