Pheidole arboricola ^HNS new species

Types INBio.

etymology L arboricola ^HNS, tree-dwelling, alluding to the arboricolous nests of the species.

Diagnosis A very small species, close to amazonica ^HNS, mackayi ^HNS, minutula ^HNS, and especially quercicola ^HNS, distinguished in the major from these species by its subangulate (as opposed to lobate) humerus in dorsal-oblique view, rounded lateral borders of the postpetiole, and bicolorous head.

Measurements (mm) Holotype major: HW 0.76, HL 0.84, SL 0.40, EL 0.06, PW 0.40. Paratype minor: HW 0.42, HL 0.46, SL 0.40, EL 0.06, PW 0.26.

color Major: head capsule anterior to eyes, along with a fuzzy circular spot in the middle of the capsule dorsum, light brown. Waist and gaster also light brown; rest of body and appendages dark yellow. Minor: body medium brown, tarsi yellow, rest of appendages light brown.

Range Atlantic lowlands of Costa Rica, up to 500 meters elevation.

Biology John T. Longino (1997) reports arboricola ^HNS as a resident of moist mature and second-growth forest, nesting in the hollow branches and under the dead bark variously of Bauhinia, Cecropia, Stryphnodendron, and other trees.

Figure Upper: holotype, major. Lower: paratype, minor. COSTA RICA: La Selva Biological Station, near Puerto Viejo (J. T. Longino). Scale bars = 1 mm.