Pheidole erratilis Wilson, 2003, new species

Pheidole erratilis new species

Types Mus. Comp. Zool. Harvard.

Etymology L erratilis, wanderer, alluding to the wide range of habitats occupied in Costa Rica.

Diagnosis A relatively large, brown member of the flavens group distinguished by a combination of exceptionally long pilosity and prominent, "sharkfin" shape of the humerus in major and minor, and narrow occiput surmounted by a collar in the minor. Similar to petersoni of Costa Rica but with longer pilosity and absence of rugoreticulum on the mesosoma in both castes, and more extensive cephalic carinulae in the major (but less extensive in the minor).

See also these less similar species: angulifera, ecuadorana, pariana, polita (in the tristis group), tennantae, schmalzi, and styrax. Measurements (mm) Holotype major: HW 1.06, HL 1.12, SL 0.62, EL 0.12, PW 0.48. Paratype minor: HW 0.56, HL 0.62, SL 0.60, EL 0.14, PW 0.34.

Color Major: gaster medium brown, tarsi dark yellow, rest of body and appendages light reddish brown. Minor: body dark, almost blackish brown, appendages light reddish brown.

Range Widespread in wet forest to 800 m in Penas Blancas and 2000 m in Braulio Carrillo (J. T. Longino 1997).

Biology Longino (1997): nests in dead wood and dead stems in leaf litter on the forest floor. In the Osa region, a colony was found in necrotic cavities beneath the bracts of a live Costus inflorescence.

Figure Upper: holotype, major. Lower: paratype, minor. COSTA RICA: 3 km south of Arenal Volcano, 700 m (J. T. Longino). Scale bars = 1 mm.