Pheidole erratilis Wilson 2003

= Pheidole JTL-048
= Pheidole JTL-051

Suggested synonym:
= Pheidole petersoni Wilson 2003

Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia

worker face view

worker lateral view

major face view

major lateral view


Minor worker: head length 0.61-0.67mm, head width 0.58-0.62mm, scape length 0.59-0.66mm, Webers length 0.77-0.90mm (n=2). Head rounded behind; promesonotum evenly arched, mesonotal suture absent; humeri projecting as tubercles, each bearing a long seta; propodeal spines short; face smooth and shining; mesosoma punctatorugose with varying degrees of smooth shiny spaces on pronotal dorsum and sides; gastral dorsum smooth and shining; dorsal pilosity abundant, long, flexuous; color red brown.

Major worker: head length 1.11mm, head width 1.08-1.16mm, scape length 0.61-0.65mm (n=2). About anterior half of face with longitudinal, subparallel rugae, those between frontal carinae extending more posteriorly in some specimens, nearly absent in others, rest of face smooth and shining; hypostomal margin flat, with small, rounded, inconspicuous median tooth, and pair of stout, sharp teeth about one third distance to recessed teeth flanking mandible bases; dorsal pilosity abundant; pilosity on sides of head variable, abundant and suberect to short, subdecumbent, and somewhat inconspicuous.


Costa Rica: widespread in wet forest areas, to 2000m in Braulio Carrillo, to 800m in Penas Blancas.

Natural History

This species occurs in wet forest leaf litter and nests in dead wood or dead stems.

Selected Records

La Selva: nest in Lecythis pod on ground.

Braulio Carrillo, 1100-2000m: 4 Winkler samples.

Braulio Carrillo 600m: 1 collection (no additional data).

Penas Blancas Valley: new second growth veg.; bananas, Piper, tall grass. Nest in dead Piper stem. [types of petersoni Wilson]

Penas Blancas: 1 Winkler sample.

Volcan Arenal Observatory Lodge: nest in dead wood on ground in forested ravine.

Osa region: 1 Winkler sample.

Osa region: nesting inside a live Costus inflorescence, in necrotic cavities beneath the bracts.


Additional collections of this species have blurred the distinction between erratilis and petersoni. There appears to be one species with variable sculpture on the pronotum. The images on this page are from the same nest series as the holotype of erratilis. Click here to see the old petersoni page, which contains images from the nest series of the holotype of petersoni.

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: 7 October 2003.
Previous versions of this page: 8 December 1997
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