Libellulidae

The Libellulidae is the largest family of Odonata and is distributed around the world. Adult libellulids are distinguished from other anisopterans by the large eyes meeting dorsally at the top of the head; many of them have the wings strikingly patterned with bands and spots or are fully colored. Adults of most species are perchers, although those of lotic waters behave mostly as fliers; many species exhibit strong territorial behavior. The nymphs are principally bottom-dwellers, inhabiting both lotic and lentic environments, including phytotelmata. They are characterized by the spoon-shaped labial palps, the absence of a longitudinal central sulcus on the ventral surface of the prementum, and the lack of male and female gonapophyses. Ninety species in 45 genera of libellulids have been recorded in Thailand, with Lyriothemis and Orthetrum as the most speciose genera with 8 species each, whereas some others, including Amphithemis, Atratothemis, Nesoxenia, Phyllothemis, Pseudothemis, Pseudotramea, Risiophlebia, and Tyriobapta, are still unknown in the nymphal stage.