Pheidole arachnion, Wilson, E. O., 2003

Wilson, E. O., 2003, Pheidole in the New World. A dominant, hyperdiverse ant genus., Cambridge, MA: Harvard University Press : 656

Pheidole arachnion new species

Types Mus. Comp. Zool. Harvard.

Etymology Gr arachnion , cobweb, alluding to the loose rugoreticulum on the head of the major.

Diagnosis A member of the tristis group characterized by the following combination of traits.

Major: dark reddish brown; sides of head covered by loose rugoreticulum (i.e. with large interspaces); humeri and postpetiolar nodes seen from above cornulate (horn-shaped); lacking any trace of antennal scrobes.

Minor: propodeal spine reduced to an obtuse angle; body entirely smooth and shiny except for several carinulae on anterior half of dorsal surface of head, one of which loops on each side of the head in a semicircle from the end of the frontal lobe to the anterior clypeal border; a thin nuchal collar present.

Very similar to iracunda , also of Costa Rica, but differing in details in the characters as listed and illustrated. Measurements (mm) Holotype major: HW 1.80, HL 1.98, SL 0.76, EL 0.18, PW 0.90. Paratype minor: HW 0.60, HL 0.62, SL 0.74, EL 0.10, PW 0.40.

Color Major: body and mandibles dark reddish brown, other appendages light reddish brown. Minor: body plain medium brown, appendages brownish yellow.

Range Known from the Atlantic lowlands of Costa Rica.

Biology A nest was found in rotting wood in forest at the La Selva Biological Station, near Puerto Viejo.

Figure Upper: holotype, major. Lower: paratype, minor. COSTA RICA: Rio Reventazon, 3-5 km east of Turrialba, Cartago (William L. Brown). Scale bars = 1 mm.