Pheidole psilogaster Wilson 2003

Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia

worker face view

worker lateral view

major face view

major lateral view


Minor worker: head length 0.65mm, head width 0.56mm, scape length 0.82mm, Webers length 0.80mm (n=1). Head evenly rounded behind, without vertex collar; promesonotal and metanotal grooves well impressed; propodeal spines of moderate length; face smooth and shiny; pronotum smooth and shiny; katepisternum evenly foveolate, anepisternum somewhat impressed and more feebly foveolate relative to katepisternum, dorsum of mesosoma smooth and shiny; sides of propodeum evenly foveolate, dorsum more feebly foveolate than sides; gaster smooth and shiny; pilosity moderately long, flexuous; color dark brown or yellow (Osa).

Major worker: head length 1.11mm, head width 1.06mm, scape length 0.82mm (n=1). Posterior half to two thirds of face smooth and shiny with scattered piligerous punctures, anterior face shiny, rugose; hypostomal margin with pair of widely-spaced teeth, each tooth sharp and needle-like, located near small recessed tooth flanking mandible; head and mesosoma with abundant, long, erect, flexuous setae, including abundant suberect setae projecting from sides of head in face view; gaster with contrastingly shorter pile, beginning with dense, short, suberect setae near postpetiolar insertion, grading into shorter, suberect pubescence posteriorly.


Mexico (type locality), Nicaragua, Costa Rica. Costa Rica: Atlantic slope to 1200m and southern Pacific lowlands.

Natural History

This species occurs in mature wet forest. It recruits to baits on the forest floor.

Selected Records

La Selva: forest floor baits, Malaise trap.

Winkler samples from Braulio Carrillo National Park (1220m), Penas Blancas Valley, and the Osa Peninsula (Rancho Quemado).


We used to recognize a light-colored form of P. psilogaster as a separate morphospecies, JTL-077. Click here for original species page and images.

Page authors:

John T. Longino, The Evergreen State College, Olympia WA 98505 USA.

Stefan Cover, Museum of Comparative Zoology, Harvard University, Cambridge MA 02138 USA.

Date of this version: 19 October 2007.
Previous versions of this page: 8 December 1997
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