Pheidole megacephala (Fabricius)

Wilson, E. O., 2003, Pheidole in the New World. A dominant, hyperdiverse ant genus., Cambridge, MA: Harvard University Press : 549-550

Pheidole megacephala (Fabricius)

Formica megacephala Fabricius 1793: 161. Combination in Pheidole by Roger 1863b: 30. Extensive synonymy and citation of infraspecific forms cited by Bolton 1995b.

Types Unknown.

Etymology Gr L megacephala , large-headed, referring to the major.

Diagnosis Major and minor: in side view, entire postpetiole oval in shape, with all of the ventral margin bulging in a conspicuous convexity, and the node oval, low, and weakly developed; mesonotal convexity absent, the promesonotal profile forming a nearly smooth semicircle; color brownish yellow.

Major: outline of head plus mandibles in full-face view forms a near-perfect heart shape; rugoreticulum present between eye and antennal fossa.

Minor: occiput broad, lacking an occipital collar.

Measurements (mm) Major (Grand Bahama Island): HW 1.32, HL 1.32, SL 0.64, EL 0.18, PW 0.60. Minor (Grand Bahama Island): HW 0.54, HL 0.62, SL 0.66, EL 0.12, PW 0.34. color Major and minor: brownish yellow.

Range Widespread although spottily distributed, and sometimes locally very abundant, from southern Florida, Bermuda, and the Bahamas south through the West Indies, southern Mexico, and Central America, to as far south in South America as Santa Catarina, Brazil.

Biology The colonies, which are continuous, with no evident pheromone-based boundaries, and large numbers of fertile queens, are able to reach enormous size. In some areas, especially islands such as Madeira, Culebrita, and the Dry Tortugas, they form a virtually continuous supercolony that excludes most other ant species. They do best in relatively moist, disturbed habitats, thus thrive around human habitations and in cultivated land. Nest sites are highly variable, from within and beneath rotting logs and underneath rocks and sidewalk flagstones to the bark and trunk-based detritus of standing trees. Columns of foragers travel substantial distances from one nest site to another and to food sources. P. megacephala are aggressive toward other species, and war with populations of such locally dominant species as the Indo-Australian weaver ant Oecophylla smaragdina and the cosmopolitan Argentine ant Linepithema humile (= Iridomyrmex humilis ). General accounts of this important species are given by Wilson (1971), Holldobler and Wilson (1990), and D. F. Williams et al. (1994). A bibliography of the ant for North America is provided by D. R. Smith (1979). The devastating effect on the native Hawaiian insect fauna was described by the pioneering entomologist R. C. L. Perkins (1913).

Figure Upper: major. Lower: minor. BAHAMAS: Grand Bahama Island. (Type locality not cited.) Types not seen. Scale bars = 1 mm.