Diversity of scorpions (Arachnida: Scorpiones) in Polonnaruwa Archaeological Reserve, Sri Lanka

Sri Lanka harbours 20 scorpion species belonging to four families, of which 15 are endemic. The distribution and ecology of scorpion fauna in Sri Lanka is poorly known. In this study, we surveyed the diversity of scorpions in the Polonnaruwa Archaeological Reserve in the dry zone of Sri Lanka. Microhabitats were thoroughly observed using the direct visual encounter method and UV lights from July to November 2018 for about seven hours (19.00–02.00 h) by two to three observers. Species, abundance, age/sex, and microhabitat features were recorded. Diversity indices, including α-diversity and β-diversity, were calculated. Heterometrus swammerdami was the most abundant species recorded, while Isometrus thwaitesi was the rarest. Reddyanus loebli and R. besucheti were common in both open and forest habitat types. Charmus laneus was recorded for the first time in Polonnaruwa. The highest Shannon Index and Margalef Diversity Index values were recorded in open habitats, but species evenness was low compared to forest habitats. Sørensen index values showed a 58% species similarity between two habitats. The results presented here contribute to the knowledge of the diversity of scorpions in these historically significant sites. This can serve as a basis for future research on the impact of habitat modification and fragmentation on populations, distribution and ecology of scorpions.