Xuan Son in late October

*This posting was updated on November 15, 2025. Please refer to Kompier et al. (2021) for more information: The genus Planaeschna McLachlan, 1895 and its subgroupings in Vietnam, with descriptions of three new species (Odonata: Aeshnidae). Also, the genus Planaeschna has been synonymized with Aeschnophlebia. I have added the current names between square marks [] below for clarity.

With apologies for the lack of postings in recent months. I have been busy writing papers.

Saturday October 21 I decided to go to Xuan Son. I have had little time recently, but now is the time the Planaeschna [Aeschnophlebia] fly there. In fact this was the only weekend available to go, so although the weather was not very promising, I went anyway. For three years I have been catching a small pale-faced Planaescha female, but never a male. I was getting a little desperate, as this was the last chance I had.

The weather was a little better than expected and quite soon I caught another female. Then several hours nothing, but fly by's of the large Planaeschna spec. nov. female and of female P. guentherpetersi [Aeschnophlebia ishigakiana guentherpetersi]. I did in the meantime tun into something unexpected: a male Coeliccia chromothorax. The 8th species of this genus along this 1.5 km stream. No idea how it got there. It is a striking species and I had never seen it on a large number of previous visits. Strange.

I also found a female Cryptophaea vietnamensis. In itself that is not strange, but it was covered in algae. I remember a discussion on this on the Facebook page on neotropical dragonflies. I do not remember ever having seen it in Vietnam, but apparently it does happen here too.

And then I caught a male "large" Planaeschna spec. nov. [described now as Aeschnophlebia tsuchi] and shortly after a much smaller one: the pale-faced male [In fact not the male of the pale-faced females, but Aeschnophlebia cucphuongensis]! I now have the males of all four species of Planaeschna occurring on this particular stream, 3 of them new to science.

Female Cryptophaea vietnamensis. Note the algae on the wings and abdominal tip!

Male Coeliccia chromothorax. Exciting find!

And there it is: Male pale-faced Planaeschna spec. nov. at last! [Aeschnophlebia cucphuongensis]

Appendages very different from P. [ishigakiana] guentherpetersi

And its pale face

Aciagrion - some additional species*

*Adjusted after email conversation with Oleg. A. pallidum changed into A. hisopa.

Aciagrion is quite a speciose and difficult genus, not in the least because many of its members are tiny and thus vulnerable. Thank God that Kosterin et al. (2014) at least sorted the problem of Aciagrion approximans. I had already recorded this species from Cat Tien National Park (a teneral male), but could only ID it properly after the mess surrounding A. tillyardi had been resolved. And I recorded A. borneense and A. migratum already. But there are other species in the area and there were historical records of A. hisopa, A. occidentale, and A. pallidum (Do & Dang).

This spring turned out to be quite productive. Aciagrion approximans turns out to be in fact quite common in Lam Dong Province, where I saw large numbers, but I also recorded it from Quang Tri and Thua Thien - Hue Provinces. It stands out with its typical purplish violet color and in hand has deeply cleft superior appendages in lateral view, but with the dorsal and ventral edges parallel.

On June 11, 12 and 18 I observed Aciagrion hisopa at the same locations as where I recorded Platylestes platystylus (see previous post). All observed specimens were blue and the females did not have reddish abdomens, like A. pallidum would. A. pallidum and A. hisopa have very similar appendages and blue specimens can be confusing. In both species  the lines on the thorax can be diffuse, although they only become truly black in A. hisopa.

On June 18, again at the same site in Dak Lak Province, I noticed another small species with triangular black mark on the dorsum of S8. Otherwise it was similar to A. borneense, which also occurred there, but I thought it might be A. occidentale. The appendages in lateral and dorsal view are virtually identical, but there is one important additional clue and that is that the internal surface of the superior appendages and the complete inferiors are ivory white in A. borneense.

The last species to mention is a blue-and-black species from Thua Thien - Hue Province. I discussed these specimens with Oleg Kosterin and we concluded that it cannot be separated from A. migratum on the basis of its appendages, even if it has a different hue. More research would be necessary to separate it (for instance through DNA analysis), but for now it seems better to treat it as a variant of A. migratum.

Aciagrion occidentale male, note the triangular mark on S8.

Probably the same male in flight

Aciagrion occidentale, female

Male Aciagrion hisopa, June 12, Lam Dong Province. Note the lack of black on the thorax

Female Aciagrion hisopa, June 18, Dak Lak Province

Another male, June 18, Dak Lak Province

A typical Aciagrion approximans, a study in violet, May 2016, Lam Dong Province

And finally Aciagrion migratum, Thua Thien - Hue Province, June 21. If you look carefully you can see the deeply incised superior appendages, but unlike in A. approximans the dorsal and ventral edges diverge.

Platylestes platystylus - also in Vietnam

May 28 I received an email from James Holden. Platylestes platystylus had been found at the fish ponds in Cat Tien National Park. Thrilling, because this is a little known and elusive species, according to the IUCN website. Dennis Farrell has reported it from Thailand, where it was known to occur, and it has also been recorded from Lao DPR. It ranges all the way west to India, although there is some doubt whether this really all concerns the same species.

Anyway, it was great to hear it occurred in Vietnam, because Lestidae are quite uncommon here, with just a few species compared to for instance Thailand. I was also rather envious, because it is a beautiful species and because I want to see every species known in Vietnam. Frustrating, because it is of course impossible to see everything.

On June 11 I was crossing the provincial border from Gia Lai Province into Dak Lak Province when I noticed an inundated depression in the open landscape. Until recently the area had been parched, but now the rains had started and water had accumulated there. It turned out it was probably the remnant of what once was a swamp. It was late in the afternoon, but I did see a few interesting damsels and decided to have a closer look. And there it was: a male Platylestes platystylus! It moved away quickly, but I had no doubt, but also no picture. While dusk settled I had to leave, but decided to return on my way back from my destination (Bao Loc).

The next morning I drove further south and into Lam Dong Province when I noticed a small shallow and grassy pond that looked promising. And there I found my second male Platylestes platystylus. Maybe not that uncommon after all, just occurring in not often researched temporary habitat?

On the way back north a week later (June 18) I revisited the depression in Dak Lak, but now in the morning. It was really crowded will all sorts of exiting species. Amongst the 35 species or so I found on the 1.5 hectare several species of Aciagrion, several Lestidae, several Ceriagrion, but also Indothemis limbata and I. carnicata side by side, and lots of other goodies. And at least 10 Platylestes platystylus. Now I had my photos sorted.

The first Platylestes platystylus male on photo, June 12 in Lam Dong Province

The same male in dorsal view

This is the female, June 18 in Dak Lak Province

Another male on June 18

Male appendages in lateral view

And male appendages in dorsal view

Nychogomphus lui, a Hanoi specialty

In 2011 Sebastien Delonglee already published photos of several enigmatic gomphid species that occur in the Hanoi region. Eventually one of these could be identified. It was Nychogomphus lui, described by Zhou, Zhou and Lu in 2005.

Apparently this species inhabits large slow rivers and the Red River is perfect for it. But it is a bit like Gomphus flavipes in Europe, another inhabitant of large rivers. That species too is best found by looking for exuviae of freshly emerged specimens. Nychogomphus lui emerges at the end of May and in early June. Sebastien has seen them for instance from a window perched in a tree! But how to reliably find them? In other years I could not. But this spring we discussed the area along the Red River where the Anax indicus appeared. It had some open forest areas close to the river. Might this be a good place?

Sebastien recently texted me to say he had seen a female. Soon after he found two more, on different days, all fresh. So today I went to the area, sweating it out (37 degrees in the shade). And found Nychogomphus lui, both a male and a female, perched in the shade close to the ground. Both were fresh. So this is the way to find them! Maybe they visit the river at dusk when mature, as other species of Nychogomphus do. Or maybe they mate elsewhere and the males do not return. We hope to find out.

For now this is the only place in Vietnam where the species has been found, but it may be more widespread. Generally we avoid the large rivers of Vietnam when we look for Odes, so it may be overlooked.

The female as I first found it, perched on a leaf. The color of the eyes shows she is very young, as is also evidenced by the shine of the wings.

She has amber wing bases. The wind was bothering her, so after this shot she took off

But when I turned around there was this wonderful fresh male! He had appeared while I was taking pictures of the female. Note the waved inferiors and black tipped superiors.

The same male in dorsal view

Another Sinorogomphus, but not very different

While visiting the mountains along the Laotian border close to Da Nang in the first week of May I caught a Sinorogomphus that looked very similar to S. sachiyoae. But the lateral pattern on S2 was somewhat different and upon close inspection the shape of the tips of the superior appendages was also different, if not a lot. I thought it had to be S. sachiyoae, but after consultation of the literature it turned out to be a species described already in 1969 by Asahina: Sinorogomphus vietnamensis. A nice and interesting addition to my list. In fact I observed the species in Quang Tri, Quang Nam and Thua Thien - Hue Provinces.

Male Sinorogomphus vietnamensis. Note the pattern on S2 and the fact that the superior appendages seem to touch the inferiors.

The female is even more like S. sachiyoae.

In dorsal view the appendages are quite similar

But in lateral view the tip of the superior appendage is longer and bends downward towards the epiproct.

A new species of Asiagomphus*

*Updated January 1, 2020 based on the publication in 2018 in Zootaxa of my study of the genus Asiagomphus in Vietnam, which included the description of this species as Asiagomphus kosterini.

April 17 I was checking streams near Tuyen Lam Lake at Da Lat. It started as a sunny day and around 9.30 I spotted the first gomphid, perching in the middle of the stream on a stone. It was immediately obvious from the extensive yellow on the terminal segments that this was something I had not seen before. It took some effort, but eventually I was lucky enough to be able to net it. In hand my suspicions that it was an Asiagomphus species were confirmed. A very interesting species, with extremely extensive yellow markings and widely expanded S7-9. Patterning was otherwise in line with Asiagomphus and the appendages were also typical of the genus. But it is not any of the other 4 species (at least) I have seen in Vietnam and it is not any of the known species from South-East Asia either. A wonderful species and new to science! It was rather common at the stream, with at least 10 different males observed and a few females seen ovipositing.

I eventually published this species as Asiagomphus kosterini, one of a total of eight species of Asiagomphus I could confirm in Vietnam.

Asiagomphus kosterini. Note the extensive yellow markings on S7-9. A beautiful and striking species.

A male in dorsal view, showing the massive club

And in lateral view

The appendages and terminal segments in dorsal view

The world of Protosticta

Once you start looking at Protosticta species, you will find there is a whole world out there! Only recently I published a paper with Toan giving details on the currently known 9 species from this genus for Vietnam. Two of these are large and different: Protostica grandis and P. ngoai. One has very typical appendages: P. spinosa. The remaining 6 are very similar. I had not yet seen several of these, but on May 5 in Quang Tri province I found an area where I kept bumping into one of these: P. caroli (first described by Jan van Tol in 2008). It can be identified by the only partially pale S9, the stubby inferiors (compared to for instance P. socculus) and the prothorax of which always the posterior lobe is extensively dark, which extends onto the central lobe. But really one needs a microscope to settle its identity for sure.

In the same area, but on a drier slope, I ran into what seemed a "very" different species. A little smaller, it was crispier, in that the white rings on the abdomen were really white, the prothorax had only on oval black spot in the posterior lobe, it has all white S9 and under the microscope there are also important differences in the appendages (like a missing lobe). Careful checking at home showed it was none other than P. socculus.

Relatively boring P. caroli. It shares with P. socculus the broad black line over the metapleural suture. S9 is only two-thirds pale, but not truly white, and the abdominal rings are likewise not very crisp.

Another specimen, similarly with limited white on S9.

A male in hand. This specimen has minimal dark markings on the prothorax, but still all dark posterior lobe, dark extending onto central lobe in two triangles, remainder off-white. The colour of the thorax is a dull dark green. 

P. socculus. Note the very white abdominal rings, the crisp white prothorax with contrasting posterior lobe

A close-up of the prothorax. Note also that the colour of the thorax is a different green.