Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Range
Costa Rica (both slopes to 1000m).
Identification
Minor worker: head length 0.65mm, head width 0.55mm, scape length 0.77mm, Webers length 0.79mm (n=1). Head without vertex collar; promesonotal and metanotal grooves well impressed; propodeal spines moderately long; face smooth and shining; smooth shiny patches on pronotal dorsum, sides of pronotum, mesonotal dorsum, and basal face of propodeum, remainder of mesosoma foveolate; gastral dorsum smooth and shiny; erect setae short, sparse, and stiff, often with two pairs on pronotum, one pair on mesonotum; color brown, mesosoma lighter brown than head and gaster on some specimens.
Major worker: head length 0.99mm, head width 0.97mm, scape length 0.74mm (n=1); face between eyes and antennal insertions superficially rugose foveolate, fading to smooth and shiny posteriorly, extent of sculpture variable, from most of face sculptured to most of face smooth and shiny; hypostomal margin flat with pair of widely-spaced teeth, each tooth sharp and needle-like, located near small recessed teeth flanking mandibles; sides of head without erect setae; face and gastral dorsum with sparse, short, appressed setae/pubescence, and sparse, stiff, erect setae.
Taxonomic note: La Selva material has a strongly arched mesonotum, sculpture on major face beneath scapes, and erect setae on scapes of major. E. O. Wilson had identified this material as a new species with the provisional name renae. Corcovado material is similar, but the mesonotum is not quite as arched, and the gaster of the major has a few more setae. E. O. Wilson had identified this material as indistincta, presumably having compared it with type material. Material from the Central Valley and Santa Rosa looks quite distinct. The mesonotum is less strongly arched, the major scapes and gaster have no erect setae, and the major head is shinier, with reduced sculpture. Overall, specimens have a more "melted" and polished black look. E. O. Wilson had identified San Jose material of this form as piceonigra Emery, a species with type locality in Mexico, based on comparison with type material.
At present, we interpret these forms as one species with considerable geographic variation. Character variation is such that there is little evidence for sharp breaks between forms, and there is no known area of sympatry of forms.
Natural History
Pheidole indistincta is generalized in habitat preference, occurring in disturbed areas, mature forest, wet forest, and seasonal dry forest. Foragers occur on the ground and on extrafloral nectaries. Nests are in soil.
Selected Records
Santa Rosa National Park: Bosque humedo; at bait.
Guanacaste Conservation Area (Pitilla): Winkler sample.
Penas Blancas Valley: Winkler samples.
San Jose: city park (Parque Morazan); forest patch (Loma San Antonio) east of San Pedro.
Carara Biological Reserve (500m): Winkler sample.
Osa Peninsula: Winkler samples; at baits; at extrafloral nectaries.
Corcovado National Park (San Pedrillo): Recently cleared park boundary through primary forest. A few workers were on a Calathea leaf 50cm high. A dead tabanid was placed on the leaf, and majors appeared within 7min. A column led 1.5m from the base of the Calathea to a nest entrance in the ground. The nest was 10cm deep in loose clay soil. A single queen was collected. The nest seemed to occupy a baseball-sized volume.
Braulio Carrillo National Park: collections at 500m and 800m (Winkler samples).
La Selva: at baits and in Winkler samples.
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
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