Xuân Son National Park is the southeastern most extension of the Hoang Lien Son Mountain Range. Only three peaks rise more than 1000 m a.s.l.
Xuân Son National Park (130 km northwest from Hanoi, in Phu Tho Province) is a great place with its wide variety of clear streams flowing through untouched karst forest, offering superb Odonata watching.
Curiously, this national park has been an overlooked hot spot for Odonata until December 2009, when Phan Quốc Toản explored the area. It was certainly the first time that survey on dragonflies was undertaken there.
This national park is renowned for the richness of Caloptera damselflies, with some rare and endangered species. The best time (for Caloptera at least) is after the rainy season, from September to December.
I visited Xuân Son at the end of October 2013 and I was not disappointed at all! For a long time, I had wanted to go there, but I always found a good reason (e.g. autumn bird migration) to avoid a 3 hours motorcycle ride. But after reading the recent adventures of Tom Kompier on his blog odonatavietnam, I finally kicked my lazy butt into action!
One of the highlights of Xuân Son National Park is the newly (2011) described Matrona taoi, known only from Xuân Son and a locality in central Vietnam (Quang Binh Province). A Matrona species with metallic green abdomen and brown-reddish wings, lacking any milky coloured reticulation at the wing bases of the male (unlike Matrona basilaris for example).
Male Matrona taoi.
This conspicuous species is easy to find - but not abundant - in appropriate habitat (and at the right time of year of course) at Lâp and Coi villages (core area of the NP), at ca 400-450m a.s.l.
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I spotted M. taoi at this quite open stream at the edge of a dense forest (2 shots, same place but different angles), near the dam between Lâp and Coi villages. I also found there Matrona basilaris, Rhinocypha perforata, Neurobasis chinensis, Euphaea masoni and Euphaea decorata. In fact, M. taoi was in the more shady section, with vegetation on both banks (in the middle part of the pic on the right). I also netted there a female Boyeria karubei and a female of the recently described Planaeschna guentherpetersi.
A slow-moving, well-vegetated shady stream in untouched (lowland evergreen) forest in Lâp village, habitat of Matrona taoi, Noguchiphaea yoshikoae, Atrocalopteryx coomani, Cryptophaea vietnamensis, Rhinocypha arguta and Vestalaria miao. Another goody commonly found there was Coeliccia sasamotoi - recorded at just a handful of sites, in Vietnam and Laos. Tom Kompier observed also some Coeliccia poungyi in this kind of habitat (to my knowledge, Xuân Son NP is the only known locality for Vietnam of this species). More interesting, he found Coeliccia uenoi, a very rare species previously known only from Cuc Phuong NP (about 120 km southeast as the crow flies) ! Fantastic!
A clear, man-made pond, habitat of Matrona taoi (2-3 males spotted), Rhinagrion hainanense, Coeliccia sasamotoi, Ceriagrion fallax and C. chaoi, the two latter in the most open part of the pond, where a carpet of algae can develop - on the right of the pix (Thanks Tom for showing me the place!).Some photos taken during this trip :
Male Matrona basilaris.
A new species for me. In Vietnam, it is a local and quite uncommon inhabitant
of forested streams both in lowland and mountains.
Male Vestalaria miao.
Another most-wanted species at Xuân Son NP. Described in 2001, well distributed in southern China, but known from very few localities in Vietnam (Huu Lien Nature Reserve, Xuân Son NP at least).
Males are easily distinguished from other Vestalaria ssp. by their very short inferior appendages (about 1/4 the length of the superiors).
Male Noguchiphaea yoshikoae.
Looks superficially like Vestalaria miao, but caudal appendages completely different. Found at ca 400m a.s.l at Xuân Son National Park, which is one of the lowest elevation known for this species. In Vietnam, recorded at least from 2 other localities: Ba Vi and Tam Dao NPs.
A territorial wing-clapping of a male Neurobasis chinensis.
Probably the commonest Caloptera in Vietnam - with Aristocypha fenestrella.
Probably the commonest Caloptera in Vietnam - with Aristocypha fenestrella.
Male Rhinocypha arguta.
One of the highlights of this trip. Described from Phu Kradung mountains (Thailand) in 1997, actually only known from 4 separated sites in Thailand and Vietnam (Cuc Phuong, Xuân Son NPs).
Female Rhinocypha arguta.
Female Rhinocypha perforata for comparison.
A common species throughout its wide range, but surprisingly scarce around Hanoi.
Male Rhinocypha perforata.
Male Euphaea decorata.
Male Rhinagrion hainanense.
This gorgeous creature has been described from Hainan in 2001, and is actually known from southern China, Thailand, Laos and a handful of sites in northern and central Vietnam. Apparently, this stream-dweller can also breed in forest ponds (I had another sighting at a man-made pond at Tây Thiên/Tam Dao NP).
Female Rhinagrion hainanense. 
Male Coeliccia sasamotoi, a recently (2011) described species, recorded
at just a handful of localities, in Vietnam and Laos.
Male Coeliccia onoi.
Pair of Ceriagrion bellona in tandem.
A first record for Vietnam, found by Tom Kompier alias “eagle eyes” one week before this trip.
Pair of Ceriagrion fallax in tamdem.
A rather common species in northern Vietnam, in sub-montane and montane localities.
Female Planaeschna guentherpetersi ovipositing in a dead trunk, 30cm above the water.
Also a newly described species (2013) from Xuân Son National Park.
Female Boyeria karubei.
A first record for Vietnam, by Tom Kompier also.
A large-sized and really stunning dragonfly.
I also bumped into this nice guy, a Green Pit Viper (Trimeresurus sp.).
Due to its green color, it is hard to see. Better not to be bitten by any of the Green Pit Vipers, their venom – while not usually deadly – is quite strong and can cause havoc in the human body.
More informations about Caloptera damselflies at Xuân Son National Park here.
Mr Lâm, at Du village (3 km from Lâp village), can provide basic accommodation at the cost of 150.000 dôngs/night.
