Saturday, 19 July 2014

Paracercion v-nigrum - new for Vietnam

On June 24 I ran into something totally unexpected. In a hamlet along the TL212, just north of the border between Bac Kan and Cao Bang Provinces, I ventured to check some rice fields bordering a small stream. These had been freshly planted and contrary to expectation, produced some interesting species. There were quite a few Aciagrion migratum around, Ischnura aurora and I. carpentieri, Ceriagrion azureum, Paracercion melanotum and something that looked very much like a Coenagrion species. For those who do not know, well, there are no such species in Vietnam as far as we know. I was able to catch the one male I could find. The next day I went back and after a long search located another male and took some pictures. After that I had some online discussions with Oleg Kosterin and as a result went back to the same location on July 7. Although the place had altered, with the rice shooting up, I did find yet another male in the same general area. A further visit on July 11 however did not produce anything, as all field were more or less dry.
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)

No comments:

Post a Comment