Diversidad de arañas (Arachnida: Araneae) en el Parque Nacional Natural Isla Gorgona, pacífico colombiano

Abstract

In order to establish an approximation to the araneofauna in the Isla Gorgona, located in the Pacific Ocean at approximately 60 km from the SW coast of Colombia, we took samples in July 2003, using various methods such as capturing the spiders manually, pitfall traps, sweeping with an entomological net, and beating foliage. The samples were taken during the day and night, at four different levels of vertical stratification, in six different habitat which had different states of succession. Sixty-five samples were taken; 1398 spiders were collected and placed in 247 morphospecies, which belong to 34 families. The data were analyzed with 7 species richness estimators: ACE, ICE, Chao 1, Chao 2, first order Jack-knife, second-order Jack-knife, and Bootstrap. The richness estimators varied between each other, with bootstrap having the lowest value (302) and ICE having the highest (504). The failure of the observed species accumulation curve to find an asymptote, showed that more sampling is needed. The most effective method applied was manual collection, with which 33 of the 34 families were collected. The Bray-Curtis similarity index showed that similarity between habitat is very small. Even though Gorgona has a small extension, it presents a high diversity of spiders, which is reflected in the number of families, that is equivalent to 71% of those found in the whole country.