Introduction

Dragonflies and damselflies compose the order Odonata, with dragonflies classified in one of the three suborders, Anisoptera. Dragonfly nymphs develop in practically any type of standing or running freshwater, and all species around the world are voracious predators, feeding exclusively on living prey. To date, 6404 species of Odonata have been described worldwide, but the nymphs are still poorly known, especially in tropical regions. Several studies have demonstrated the value of using odonate communities or assemblages as indicators of ecosystem integrity; thus, it is important to have updated keys for the identification of the nymphs. Most of the knowledge on the nymphs inhabiting Thailand presented here has been gleaned from descriptions of taxa from other parts of Asia, although 11 genera of Anisoptera are still unknown as nymphs. A list of the 221 species of Anisoptera recorded for Thailand is also included.