Species Diversity of Spiders (Araneae) Along an Elevational Gradient in Mt. Busa, Lake Sebu, South Cotabato, Philippines

Spiders (Araneae) are one of the most significant groups of insectivorous predators, occupying almost every niche in terrestrial ecosystems. However, there is limited information on the spider fauna in the Philippines. Thus, this study was designed to address this gap and investigate the composition, abundance, and diversity of the spider fauna found in Mt. Busa, Lake Sebu, South Cotabato, Philippines. This study also assessed the relationship between the spider community and the physicochemical parameters of the elevational gradients used in this study. Sampling was conducted for three field days on the elevational gradients of Mt. Busa, namely the open habitat, lower montane (open and close canopy forest), and upper montane. Spiders were collected using opportunistic sampling, sweep netting, and hand-picking methods. A total of 206 individuals belonging to 31 species under 22 genera and 7 families were collected. Leucauge decorata from the family Tetragnathidae was the most abundant and common species in the study area. In addition, a possible new record species was found at the lower montane open canopy forest. Spider assemblages were analyzed using PAST software 4.03. Diversity was highest (H' = 2.154) at the mid-elevation (lower montane open canopy forest) and lowest (H' = 1.399) at the higher elevation (lower montane close canopy forest). A slightly even distribution was recorded. The spiders were found to belong to five functional groups (guilds) based on their foraging behavior in the field. The orb-web weavers was the dominant guild (46%) followed by the ground runners (22%). Results indicate that elevation and habitat type affect the species richness and abundance of spiders.