Species Composition of Odonate Fauna in Meegahawatta, a Wetland Area in Hanwella, Sri Lanka

Abstract

Approximately 120 species of Odonata (Zygoptera and Anisoptera) have been recorded in Sri Lanka to date. There are many gaps in our knowledge of Odonata taxonomy and distribution. The present study, therefore, was carried out to investigate adult Odonata species present in Meegahawatta area (1000m2) in Hanwella. The study was carried out using two fixed quadrats (20m x 10m) randomly established in two selected sites. Total number of individuals belonging to each species was counted fortnightly by using binoculars. A total of 27 species, 11 Zygoptera and 16 Anisoptera representing eight families were recorded. This comprised of three endemic Zygopteran species (Libellago adami, Pseudagrion rubiceps ceylonicum and Prodasineura sita) and three endemic anisopteran species (Epopthalmia vittata cyanocephala, Cyclogomphus gynostylus and Macrogomphus lankanensis). Among those identified was one recently discovered and yet un-described Archibasis species. Of the three endemic Anisopteran species recorded, C. gynostylus and M. lankanensis are listed as vulnerable species in the IUCN Redlist of 2010. Although the Zygopterans showed higher Diversity Index and Evenness Index (H’= 1.99, E= 0.83) than the Anisopterans (H’=1.96, E= 0.32), their Richness Index (R=1.67) was less than that of the Anisopterans (R= 2.49). The most common Zygopteran species recorded was Pseudagrion malabaricum whereas Neurothemis tulia tulia was the most common anisopteran species.