Distribution of a Costa Rican wet forest velvet worm (Onychophora: Peripatidae)

The ecology of New World onychophorans is poorly known because individuals are rare and difficult to locate in the field. The only descriptions of density and microhabitat associations are based on the field observations of a few individuals. This paper presents the results of a 300-m(2) search of leaf litter in a wet tropical forest at La Selva Biological Station, Republic of Costa Rice, during the dry season over a period of 4 mo. Density of this Epiperipatus sp. was 0.11 individuals pet square meter. The age structure of the population was biased toward juveniles, but did not include newly born onychophorans; this suggests that reproduction occurs during the wet season. Epiperipatus sp, nonrandomly selects microhabitats. It is strikingly associated ants ants; 1-m(2) plots containing onychophorans contained a mean of 7.4 ant nests, whereas plots without onychophorans had a mean of only 4.7 ant nests. In 2 instances, onychophorans were located inside large and active ant nests.