Wednesday, March 22, 2006

Status of Spider Fauna in Sri Lanka

Channa N. B. Bambaradeniya, Suresh P. Benjamin and L. D. C. Bhathiya Kekulandala
IUCN – The World Conservation Union, Regional Species Programme, 53, Horton Place, Colombo 07, Sri Lanka.
University of California, Berkeley, Insect Biology Division ESPM, 201 Wellman Hall #3112 Berkeley, CA 94720-3112.

Spiders are one of the most diverse arthropod groups, and an important component in terrestrial ecosystems. They are valuable indicators of endemism, and for early warning of ecological change. They are capable of responding more rapidly to changes in the environment than long-living vertebrates and plants. Many spiders in Sri Lanka could be used as focal species in the complex process of deciding which habitats afford conservation priority. They also function as important biological control agents of insect pests, especially in agricultural habitats. In this review we will highlight the previous research work on spiders in Sri Lanka, their species richness and distribution.

Taxonomy of spiders in Sri Lanka

In general spiders in Sri Lanka are very poorly known. Scientific documentation of spiders in Sri Lanka began with the work of Pickard-Cambridge (1869). The last comprehensive study was conducted more than a century ago by Pocock (1900). A few foreign researchers worked on a few spider families in Sri Lanka there after (Brignoli, 1972, 1975; van Helsdingen, 1985). Involvement of local researchers in spider taxonomy in Sri Lanka began with the works of Wijesinghe (1983, 1987) who conducted a preliminary survey and a review on the group. He stated that a little over 400 species of spiders are known from Sri Lanka, with an estimation of the actual total number to be close to 1000. The 1990s onwards has been a period of renowned interest on spider taxonomy in Sri Lanka, with several new species being described (Benjamin, 1999, 2000, 2001; Benjamin and Jocque, 2000; Wijesinghe, 1997, 1999a, 1999b). More recently, Bambaradeniya (2001) documented seven spider taxa (two species and five genera occurring in the oriental region) that are new records to Sri Lanka, from a rice field ecosystem at Bathalagoda.

Species richness of spiders in Sri Lanka
Based on a review of these recent advances on spiders, it could be stated that the Sri Lankan spider fauna consists of about 488 known species, under 45 families (Benjamin and Bambaradeniya, 2005). However, the actual number might be even exceeding 4000 species. Among the total species described so far, the Mygalomorphs (commonly referred to as ‘tarantulas’ or ‘bird-eating spiders’) consist of 19 species, under five families. They are dominated by the Family Theraphosidae, which is represented by 10 species currently described from the island (Smith and Kirk, 2002). The balance consists of Araneomorphs, which are dominated by the jumping spiders (Family Salticidae – 104 species). In general even the described taxa are very poorly known. Many species and even new genera await discovery and description. The taxonomical identity of most known species is uncertain as these were described without modern taxonomical standards and/or were based on juvenile specimens. Further, field work, mainly in the south western and central highlands and detailed systematic studies will be needed to provide a more complete picture of the spider fauna of Sri Lanka.

Based on Paper presented at Workshop organized by Young Biologists' Association Sri Lanka and Ministry of Forestry and Natural Resources on December 2005 at University of Sri Jayewardenepura, Nugegoda

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