Contribution to the Odonata of the Kingdom of Tonga

New data on the Odonata fauna of the Kingdom of Tonga is provided following research carried out on Tongatapu and ‘Eua islands in July 2012. New localities for Tongatapu Island are put on record and previous studies are compared with new phenological data from a period during which field surveys are rarely conducted on Pacific islands. Although Odonata have been collected before from ‘Eua Island, the data presented here is the first published so far. ‘Eua Island is assessed as a very important venue for further research on Odonata. Overall the Kingdom of Tonga is very depauperate in water resources with lotic biotopes very restricted in area and found on ‘Eua Island, and possibly on Tofua and Late islands, which are both volcanic. This study on the Odonata of ‘Eua resulted in records of eight taxa, including with Teinobasis sp. nov., which will be described elsewhere. Morphological variation in Pseudagrion microcephalum stainbergerorum and Tramea transmarina are discussed in the context of their subspecific affiliation. Diagnostic features for easier differentiation are proposed for the first of these taxa; the validation of commonly used diagnostic traits is discussed for the second.