Pheidole nitella Wilson 2003

Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia

worker face view

worker lateral view

major face view

major lateral view


Minor worker: head length 0.36mm, head width 0.34mm, scape length 0.27mm, Webers length 0.41mm (n=1). Head somewhat cordate behind; eye elliptical, located near mandibular insertion; mesonotal suture absent; propodeal spines absent, reduced to slight angles connected by a transverse carina; face, mesosoma, and gaster largely smooth and shining; dorsal pilosity moderately abundant, of moderate length, flexuous; color usually orange (see Comments).

Major worker: head length 0.68mm, head width 0.60mm, scape length 0.30mm (n=1). Head somewhat flattened; face largely smooth and shining, a few parallel, longitudinal rugae between eye and antennal insertion; eye elliptical, located near mandibular insertion; hypostomal margin with strong, pointed medial tooth, and pair of smaller teeth one half to two thirds distance to recessed teeth flanking mandible bases (Figure); dorsal pilosity abundant; head with moderately abundant, erect setae projecting from sides of head in face view.


Costa Rica (Atlantic slope to 1000m).

Natural History

Inhabits wet forest leaf litter; nests in small cavities in dead or live wood, forest floor litter layer to low arboreal zone.

Selected Records

Winkler samples and/or baiting from La Selva, Braulio Carrillo National Park (800m, 300m), Penas Blancas Valley.

Penas Blancas Valley: Nest in cavity in live vine stem, primary forest.

Penas Blancas Valley: Nest in eggshell-like Cecropia internode decaying on forest floor; primary forest.

Penas Blancas Valley: Nest under loose bark of fallen branch in forest.

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


I collected a nest series that is essentially a dark brown version of nitella. It was under a stone in a pasture, at the 1500m site (Finca Murillo) near the Barva transect in Braulio Carrillo National Park. Minor workers of this form are nearly indistinguishable from sagittaria. The propodeal spines of sagittaria are ever so slightly more developed.

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: 26 July 2005.
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