Pheidole bicornis

From Wilson (2003): In Costa Rica at least, P. bicornis is an obligate inhabitant of species of understory rainforest shrubs of the genus Piper. The ants live in cavities of the petioles and stems that they hollow out themselves. The relationship appears to be mutualistic: the workers, which seldom forage on the ground, feed on lipid-rich food bodies developing within the petiolar cavities. For their part the plants evidently benefit from the removal of the eggs and early stages of herbivorous insects (Letourneau 1983), as well as from the clearing of vines and transport of organic material into the plant by the ants during nest construction (Risch et al. 1977).

Identification
See the description in the nomenclature section.

Distribution
From Wilson (2003): Costa Rica, Panama. In Costa Rica the species has been found in both the Atlantic and Pacific lowlands (Longino 1997) and to an elevation of 1270m (Risch et al. 1977).

Distribution based on Regional Taxon Lists
Neotropical Region: Costa Rica, Panama.

Nomenclature

 *  bicornis. Pheidole bicornis Forel, 1899c: 74, pl. 3, fig. 24 (s.) PANAMA. Combination in P. (Trachypheidole): Emery, 1915i: 190. See also: Wilson, 2003: 641.

Description
From Wilson (2003): DIAGNOSIS A member of the transversostriata group and evidently close to the tristis group, easily distinguished by its small size; and in the major by the sharp, upturned horn-like extensions of the frontal lobes and heavy rugoreticulate dorsum of the head, broken in the central posterior region by a ladder-like sequence of parallel transverse carinae.

MEASUREMENTS (mm) Lectotype major: HW 0.86, HL 1.08, SL 0.38, EL 0.12, PW 0.54. Minor (San Vito, Costa Rica): HW 0.48, HL 0.54, SL 0.42, EL 0.08, PW 0.32.

COLOR Major: concolorous light reddish brown.

Minor: concolorous yellow.



'''Figure. Upper: lectotype, major. Lower: minor (Finca Loma Linda, near Agua Buena, Puntarenas, Costa Rica, col. J. Vandermeer). Scale bars = 1 mm.'''

Type Material
- as reported in Wilson (2003)

Type Locality Information
Bugaba, Panama.

Etymology
L bicornis, two-horned, referring to the cornulate extensions of the frontal lobes of the major. (Wilson 2003)

Additional References
Forel, A. 1899e. Formicidae. [part]. Biol. Cent.-Am. Hym. 3: 57–80.

Letourneau, D. K. 1983. Passive aggression: an alternative hypothesis for the Piper-Pheidole association. Oecologia 60:122–126.

Risch, S., M. McClure, J. Vandermeer, and S. Waltz. 1977. Mutualism between three species of tropical Piper (Piperaceae) and their ant inhabitants. Amer. Midl. Nat. 98(2): 433–444.

Text and images from this publication used by permission of the author.