Coexistence of four orb-web spiders in an oil palm plantation in Peninsular Malaysia

Abstract

Thirty adult female individuals of each of the four orb-web spider species namely Araneus sp. (Araneidae), Gasteracantha kuhli Koch, 1837 (Araneidae), Gasteracantha hasselti Koch, 1837 (Araneidae) and Opadometa grata (Simon, 1877) (Tetragnathidae) were randomly sampled between 1000 and 1400 h from May to July 2017 in an oil palm plantation in Perak, Malaysia. Morphological and web characters of these orb-web spiders were obtained and analyzed using principal component analysis (PCA) and bootstrapping methods. For the morphological characters, the PCA results captured a total of 99% of the variance and indicate that the Araneid species have distinct clustering. For the web characters, the PCA captured 76% of the total variance and did not show any distinct clustering with significant overlapping between them. Moreover, the mean and 95% confidence intervals using bootstrapping identified significant differences in the morphological and web characters for most spider species with little overlap. This study indicates that the four orb-web spider species could coexist in terms of their spatial territory and food resources in the oil palm plantation, suggesting that these resources were not a limiting factor.