Keys to Suborders and Families of Odonata of Thailand

Keys to the Odonata nymphs of the two suborders and of the seven families of Anisoptera that inhabit Thailand are provided. Detailed photographs of the most important features are included. The presence of only four antennomeres distinguishes Gomphidae from all other families. Aeshnidae differs from the remaining families by the flat prementum. Nymphs of Chlorogomphidae and Cordulegastridae are distinguished by the ligula with a median cleft and the distal margin of labial palps cut into large, irregular teeth. Macromiidae nymphs present the anterior margin of the frons reflexed as a horn or with papilliform tubercles on different parts of the head or both. The presence of a ventral, basal, longitudinal median sulcus on the prementum distinguishes Corduliidae from Libellulidae.