A Report on the Formicidae of the 2000m site, Barva Transect, Braulio Carrillo National Park

Page author: John T. Longino, The Evergreen State College, Olympia WA 98505 USA.longinoj@evergreen.edu

The 2000m site is cold cloud forest habitat, and ants are very low density. This is near the upper elevational limit for ants in tropical montane forests, and casual inspection of the site may suggest there are no ants at all. Closer inspection reveals a few low-density species, but one has to look quite carefully. However, a combination of hand collecting and the intensive quantitative sampling by Project ALAS revealed more ant species than I expected. A total of 19 species were obtained during the 2002 expeditions to the site.

In the table below, each species is linked to a species page with images. The two numbers that follow each species are the percent of miniWinkler and Malaise samples, respectively, in which the species occurred, from a total of 200 miniWinkler and 100 2-week Malaise samples.

Adelomyrmex JTL-006 4% 0%
Adelomyrmex tristani 10% 0%
Discothyrea testacea 7% 0%
Gnamptogenys simulans 1% 0%
Hypoponera JTL-001 17% 0%
Labidus coecus 2% 0%
Leptothorax salvini 0% 13%
Linepithema iniquum 0% 0%
Pachycondyla aenescens 0% 4%
Pachycondyla ferruginea 8% 0%
Pheidole boltoni 1% 5%
Pheidole innupta 0% 7%
Pheidole JTL-103 1% 0%
Pheidole umphreyi 12% 0%
Pyramica JTL-006 4% 0%
Stenamma JTL-006 30% 0%
Stenamma JTL-017 2% 1%
Stenamma JTL-018 0% 0%
Stenamma schmidti 40% 0%

Stenamma were the dominant ants in the leaf litter. The most visible arboreal ant species was Leptothorax salvini, and these could be found relatively easily by hand collecting. Two species are uniques for the site, collected only once: Linepithema iniquum was collected by Kenji Nishida, from a tree in the old clearing around the refuge, and Stenamma JTL-018 was collected from one Berlese sample. Gnamptogenys simulans is also a unique if only workers are counted; workers were collected in one miniWinkler sample. However, Kenji also found an adult male on the ground near the refuge building.

Date of this version: 29 June 2003.
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