The middle of May I was alerted by Toan that he had seen an unknown species of Megapodagrionidae at Pia Oac, a place I regularly visit myself. Excitedly I went to check, after I had met with Toan in Cao Bang and seen his specimens, which showed indeed something very unusual. On May 20 I visited Pia Oac and saw 2 males of his species. On May 31 I visited again and this time saw at least 6 males. The female still needs to be located.
This is a robust damselfly, that sits on exposed branches, twigs, vines and sometimes leaves in shady places along a stony stream under forest cover. As it sits quietly with wings spread out it is easy to overlook, where it not for the bright blue abdominal tip. Otherwise it is quite dark in appearance. Apart from the curved superior appendages the forked inferior is also striking. After initial bewilderment Wen-Chi Yeh helped me out by pointing to Priscagrion. Subsequent communication with Keith Wilson confirmed his suspicion that this is a Priscagrion species. Priscagrion was described by Zhou & Wilson in 2000 and contains two species, Priscagrion kiautai and P. pinheyi. Although P. kiautai has darkened wingtips in the description, based on specimens from Guizhou Province in China, the other characteristics seem to fit very well, notably the exact shape of the appendages. Although subsequent research may point out this it in fact a closely related, but different, (sub)species, for the moment it seems safe to identify the mystery damsels as P. kiautai, a great addition to the Vietnamese fauna.
|Priscagrion kiautai in its dark surroundings|
|A different male enticed to sit on a leaf on May 31|
|Facial pattern of the male|
|The same species in hand on May 20|
|Appendages in dorsal view|
|And in lateral view. The shape of the inferiors is intriguing.|