Thanks to the close-ups I received from Xin Yu I could verify my initial suspicion that this is Paracercion v-nigrum, although the v-mark on S8 that gave this species its name is missing. Oleg did voice his doubts on the specific identity. The possibility remains that this is an as yet undescribed closely allied species. Nevertheless, the pattern of black and blue on the abdomen and thorax are as one would expect of P. v-nigrum (in view of the apparent variability in the presence or absence of the black v on S8 I consider this of no consequence), and the shape of the appendages is the same. Although the species is very Coenagrion-like in appearance (as is v-nigrum), it does have the greenish lower half of the eyes of many Paracercion species and the tiny speck of blue in the otherwise black humeral stripe also points to this genus. The appearance of this species in Vietnam should raise some eyebrows, as it is known from central China northward (Shaanxi, Hubei, Sichuan).
|Paracercion v-nigrum, male|
|Paracercion v-nigrum, male, in flight|
|Paracercion v-nigrum in hand. Note th blue in the humeral stripe and the greenish eyes. The shape of the black on the dorsum of S2 is rather variable (see other pictures).|
|Close-up of appendages (apologies for the rather poor quality)|
|Old shot of appendages of Paracercion v-nigrum for comparison (courtesy of Xin Yu)|