Paracercion malayanum (Selys, 1876)

During summer 2012, under terrible heat, I spent a couple of hours in Van Long Natural Reserve (pic above) trying to get decent shots of Paracercion malayanum and the other interesting Coenagrionids hanging around.

 Paracercion malayanum (left) sharing the same water lily with P. calamorum.

 

Of course, all those little buggers were flying or sitting 5-10 meters from the water's edge, so I had to enter into the water up to the belly - much more than I first expected, and slog through shoe-sucking mud ! A perilous adventure for my camera, and my sandals also...



Among the pond damselflies, Paracercion malayanum and P. calamorum are the only ones I often seen lying flat on floating debris, carpets of algae, water lilies... A characteristic of this genus ?

At Van Long, I didn't get to see any females, but the males were commonplace. These are the best natural photos I have managed so far.

This male have stunning azure blue eyes.
Thorax has middorsal black stripe, a broad bluish-green antehumeral stripe of even width. 

The black humeral stripe enclose one or two tiny light comma (this feature seems to be constant ; I have noticed this on all the specimens spotted in the field and also on all the pics of this damselfly available on the web).

S2 present a broad dorsal band, constricted in the middle, pointed apically, broad dorsally, which recalls the shape of a "8".

S3-6 have broad complete dorsal bands, each of them (except S6) with an apical “ace of spades”-like dilatation.

S8-9 are azure blue, unmarked ; S10 is blue, with a narrow dorsal black band.

Cercion malayanum is a widely distributed and probably under-recorded species. Known to occur in India, Indonesia, Nepal, Philippines, Sri Lanka, Thailand.

This cute bluish-green damselfly is not in the Checklist of dragonfly from Vietnam (Dô Manh Cuong & Dang Thi Thanh Hoa, 2007). 

I have no information about its current status in Vietnam. I just can say that, in my area (i.e. within a 100-120 km radius around Hanoi), it is a scarce inhabitant of clear, open ponds. I know it from only a handful of locations. This species is common at Van Long but is much less numerous than Paracercion calamorum.

Nota : Paracercium malayanun is an Indo-Malayan species. Further north, it is replaced by the Sino-Japanese P. melanotum, a very similar-looking species. The latter is very likely to occur in northern Vietnam.