Páramo spiders of Volcán Chiles

Spiders were collected from the páramo using pitfall traps to investigate the relationship between species diversity and abundance with habitat type and altitude. An altitudinal range of 3300-4300m was used with traps being set in various habitat types: zonal páramo grassland, riparian zone, Polylepis woodland, mire and scree (talus). The body length of spiders from the zonal grassland was also measured. Páramo spiders employed a wide range of hunting strategies and exhibited differences in body size that may restrict competitive interactions and permit coexistence. However, there is some evidence that certain groups may be negatively associated. Specialisation to particular habitat types appears to be limtied to a relatively large number of rare species, and common spiders were not habitat-restricted. Polylepis woodland assemblages were most distinct from those of the other habitat types. In the zonal páramo, a significant decline in spider abundance and diversity coincided with the change from grassy páramo to cushion páramo (superpáramo) at around 4000-4100m. The reduced structural complexity of vegetation above this transition zone provides fewer potential niches for the spider and prey. The species diversity of vegetation decreases with altitude and may limit the range of prey availability, again related to the decline in the diversity and structural complexity of vegetation at higher altitudes. It is suggested that future studies should define morphospecies and focus on functional attributes of spiders (e.g., feeding strategies, body size): this would provide useful ecological information as well as specimens for taxonomic work in developing keys for párarmo spiders.