Abstract
Dragonflies and damselflies (Order Odonata) are among the most widely used freshwater bioindicators globally, owing to their complex aquatic larval stage, sensitivity to water quality and habitat condition, and well-developed taxonomy. South India, encompassing the states of Tamil Nadu, Kerala, Karnataka, Andhra Pradesh, and Telangana, harbours one of the most diverse odonate faunas in Asia, with the Western Ghats recognised as a global centre of Odonata endemism.
Despite this significance, comprehensive taxonomic inventories and functional identification keys for South Indian
dragonflies remain outdated or regionally incomplete. This study presents a systematic faunal survey of dragonflies
(Anisoptera) from 68 freshwater habitats across South India, conducted between 2019 and 2021, documenting 186
dragonfly species from 68 genera and 11 families. Forty-two species represent new state records, and 8 are putative new
species pending formal description. The families Libellulidae (84 species) and Gomphidae (38 species) dominate the
regional fauna. Species richness is highest in the Western Ghats foothill streams (mean 64.8 species per site) and
declines sharply in degraded agricultural water bodies (mean 18.4 species per site). Water quality parameters, riparian
vegetation cover, and stream gradient are the strongest predictors of odonate species richness. Updated dichotomous
identification keys to all 186 species are provided, with diagnostic illustrations for 48 species. Conservation assessments
indicate that 34 species qualify as Threatened under IUCN criteria.