Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Identification
Minor worker: head length 0.84mm, head width 0.67mm, scape length 0.94mm, Webers length 1.06mm (n=1). Head evenly rounded behind, with no vertex collar; mesonotal suture moderately impressed, metanotal groove well-impressed; propodeal spines nearly absent, junction of propodeal dorsum and declivity marked by transverse carina that is slightly produced into tubercles laterally, where spines would be in other species; face, mesosoma, and gaster shiny; thin, sharp, transverse, arcing rugae on posterior face and dorsal mesosoma; gastral dorsum smooth and shiny; dorsal pilosity moderately abundant, of moderate length, flexuous; color dark brown.
Major worker: head length 1.53mm, head width 1.42mm, scape length 1.07mm (n=1). Face largely smooth and shining, with longitudinal rugae between eyes and antennal insertions; hypostomal margin with pair of small teeth; each tooth located just under half the distance from midline to small, recessed tooth flanking mandible.
Range
Costa Rica (Cordillera Central to Cordillera Guanacaste; type locality is Vara Blanca).
Natural History
This species occurs only in cloud forest habitats, where it nests in large epiphyte mats in the canopy, and occasionally in dead wood near ground level. Foundress queens occur under epiphyte mats, and in some cases pleometrosis occurs (a group of over five queens together with brood and small workers has been observed). Colonies are large, with many workers pouring forth when the nest is disturbed. Soldiers tend to stay deep within the colony. The feeding habits of this species are unknown. Foragers have never been observed outside of the nests. Observations have been almost entirely during the day, so they could forage nocturnally. Alternatively, they may have specialized and perhaps plant-derived food sources within the nests. Scattered mealybugs may be found on epiphyte roots in the nests (figure).
Selected Records
Guanacaste Conservation Area (Cerro Cacao): nest in an epiphyte clump in the elfin forest on one of the peaks.
Monteverde: numerous collections from epiphyte clumps in cloud forest canopy.
Monteverde: colony in a rotten stump at a road edge. The nest was about 1m above the ground, in elongate vertical chambers. I found one alate queen while collecting from this colony. The colony also harbored eucharitid parasitoids. There were a few adults and many pupae. The workers treated the parasitoid pupae the same as their own brood.
Penas Blancas Valley: nest in epiphyte clump in old treefall.
Braulio Carrillo National Park (1800-2000m, near Vara Blanca): nests in epiphyte clumps.
Comments
Wilson (2003) considers this species to be a junior synonym of alfaroi. The two appear morphologically identical and differ only in color. However, P. innupta and P. alfaroi are sympatric in the Vara Blanca area of Braulio Carrillo National Park, and they seem to have different nesting habits. Pheidole innupta nests mainly under epiphyte clumps and is rarely obtained in Winkler samples. In contrast, P. alfaroi is known mainly from Winkler samples and presumably nests on the forest floor. We prefer to treat them as different species.
Literature Cited
Wilson, E. O. 2003. Pheidole in the New World: A Dominant, Hyperdiverse Ant Genus. Harvard University Press, Cambridge, Mass.
Page authors:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA. longinoj@evergreen.edu
Stefan Cover, Museum of Comparative Zoology, Harvard University, Cambridge MA 02138 USA. scover@oeb.harvard.edu
Date of this version: 2 September 2003.
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