Labrogomphus torvus - new for Vietnam

I created some confusion with a vague photo of a large Gomphid on the blog over the last few weeks, when posting on Huu Lien. Well, today the riddle was solved. When I arrived at the reservoir Sebastien was already standing by the water's edge holding a Gomphid that had landed on his net! We concluded, based on the long S9, that it should be Marcogomphus, but the appendages did not seem right to me. Later, Sebastien caught a female that was eating another dragonfly. And a second male flew by and landed high in a tree. Obviously, even on December 1, there were still Gomphids around. Back at home a quick check of the literature revealed that indeed it was not a Macrogomphus, but fantastic Labrogomphus torvus, well known from Southern China, Hainan, Taiwan. A huge beast, with long legs with terrible spines on them. And very distinctive appendages. So, I will change the Marcogomphus entry…

Labrogomphus torvus, male

Same male, wing venation

Appendages in dorsal view

Labrogomphus torvus, female

A typical first of December - not

* Post adjusted on November 15, 2025. Planaeschna is synonymized with Aeschnophlebia. Kompier et al. (2021) sorted out details of Vietnamese species of this genus. Adjustments are made to below text between square brackets [].

This December 1 we spent in Huu Lien, where we ran into Sebastien, who had just, unknowingly, obtained the key to the gomphid mystery there. More on that later. It was as usual an interesting day. Smack in the middle of the forest I caught a Planaeschna [= Aeschnophlebia] female. For the time being I put it in the books as P. guentherpetersi [= A. ishigakiana guentherpetersi], the species from Xuan Son. It was marginally smaller (a few mm) and the face was darker, where it was light brown and yellow in Xuan Son, it was dark brown here, but otherwise there are no easily detectable differences. [In fact, as explained in Kompier et al. (2021), this is a closely related but different species, described in Kompier et al. as Planaeschna (= Aeschnophlebia) sp. 2.] See below:

Planaeschna guentherpetersi, female

And scanned

Face in frontal view

For comparison, the female from Xuan Son [this in fact is the same A. sp. 2, not the in Xuan Son more commonly encountered A. ishigakiana guentherpetersi]

And in hand, female from Xuan Son

A visit to Van Long - look what the cat brought in

So, what did I see at Van Long? The most interesting record was of a female Mortonagrion aborense. Now I have seen this species at Van Long, at Cuc Phuong, in Huu Lien and in downtown Hanoi. Clearly it is in fact a common species in northern Vietnam that has been very much overlooked until Sebastien ran into it.

Mortonagrion aborense, female

I also took a pretty good shot of Pseudagrion australasiae, a male. There were not many around. I saw maybe 5-6 males over the day.

Pseudagrion australasiae, male. Note the short superior appendages, half the length of S10. Otherwise very similar to P. microcephalum.

And the last species that deserves a bit of attention was Ceriagrion auranticum. There were quite a few flying and this female did me the courtesy of staying put. Note the long abdomen, protruding further beyond the wingtip than in C. nipponicum.

Ceriagrion auranticum, female, with wings up to 1/3 of S6

For convenience, the female C. nipponicum of a few posts back:

Ceriagrion nipponicum, female

And of course that other Paracercion, P. calamorum. There were still several around, including some females.

Paracercion calamorum, male

Paracercion calamorum, female

A quick visit to Van Long - The Paracercion problem*

The last several days I have been very busy with work on the one side and haunted by the Pseudagrion enigma on the other. Rory Dow suggested to look into the possibility of it being related to Paracercion impar and that is why I looked into the Paracercion article by Dumont (thank you Rory) and at the same time decided to take a closer look at the posterior view of the few specimens of Paracercion I have to see what it looks like in real life, compared to the drawings of Dumont. What a shock to find that the posterior view of the specimen from Van Long and that from Huu Lien, very similar in lateral and dorsal view, are completely different! See below first the lateral views:

The Huu Lien Paracercion species

The Van Long Paracercion species, yes there seem to be some slight differences I overlooked

But the posterior views are really revealing:

The Huu Lien specimen

The Van Long specimen

So quite a shock to find that these must to two different species, but very similar in other aspects. I work under the assumption now that the Huu Lien specimen is P. melanotum, whereas the Van Long specimen likely is (Para)Cercion malayanum.

Anyway, this is why today I drove to Van Long, to see if I could obtain a few more specimen of "malayanum". This proved difficult, as there was really not a lot going on at Van Long, even if the weather was pretty good, sunny, 22 degrees. Hardly a damsel or dragon was moving. It is strange how different the mountains in the north are compared to the Red River Deltaic area. I did see a few things of interest though, and I did collect two more males. Hopefully there will be success at Huu Lien too, tomorrow.*

* Note that I found the female of P. melanotum in Huu Lien (see the post on that subject), but I also took photos of the posterior view of the appendages of the Van Long new specimens after this post, that throw a different light on the subject. See the post: "Paracercion continued."

Here is a photo of a male perched on a floating leaf.

Paracercion cf. melanotum (explained in post "Paracercion continued"), male 

Polycanthagyna erythromelas

I am reaching the end of species that I have not published on the blog yet, but there are a few more to go. One is Polycanthagyna erythromelas, an aeshnid that is not rare, seemingly, but I have not seen it often. In fact I had only a few females flying by through the months, for instance at Tay Thien, Tam Dao National Park and once a male hanging in a tree over a small pond in a rocky stream on a hill side in Ba Be National Park in early August. I could take a few distant shots before it dropped of its perch and darted off to new and unknown adventures. This is it:

Polycanthagyna erythromelas, male

Potamarcha congener

One common dragonfly I have not yet discussed is Potamarcha congener. This is an interesting widespread species of which for once the females are very often encountered. This is because they have the habit of perching on wires in the open. Males you hardly ever see on wires. Come to think of it, I do not recall such instance, but that seems odd. Anyway, males you see at ponds, where they perch over the water on twigs, or nearby in fields on bushes. The male is a larger, paler version in some ways of Trithemis festiva, whereas the female has an interesting thoracic pattern of 4 pale lines. It also has the flanges on S8 of Orthetrum females. I have seen P. congener all over northern Vietnam and also in the Mekong Delta, although it is nowhere abundant.

Potamarcha congener, female, for once not perched on a wire (involuntarily)

Potamarcha congener, male

Another male, more pruinose on the abdomen

The Huu Lien list, until now

After last weekend and this Saturday, an update on the list for Huu Lien National Park. Sebastien mentioned his sightings also on his blog. It is good to compare our sightings with the list published for visits in June by Cuong & Toan. There are some striking differences. Marked with * not on Cuong et al. My list for now is 50 species long, but we are just scratching the surface, that much is clear and it is late November, after all.

Atrocalopteryx atrocyana, *Atrocalopterix sp. n., Neurabasis chinensis, Vestalaria miao, Vestalis gracilis, Libellago lineata, Rhinocypha biforata, R. perforata, R. cf. drusilla group ("huai"), Euphaea masoni, Ischnura senegalensis, Agriocnemis femina, A. pygmaea, *Ceriagrion auranticum, *C. nipponicum, *Mortonagrion aborense, *Paracercion melanotum, *P. calamorum, *Pseudagrion microcephalum, *P. rubriceps, P. pruinosum, *Pseudagrion sp. n., Coeliccia sp. n., Copera ciliata, C. marginipes, C. vittata, Prodasineura autumnalis, *Anax guttatus, Gynacantha saltatrix, *G. subinterrupta, *Ictinogomphus pertinax, *Labrogomphus torvus, Paragomphus capricornis, Crocothemis servilia, Orthetrum sabina, O. pruinosum, O. glaucum, Pantala flavescens, Trithemis aurora, T. festiva, *T. pallidinervis, Brachythemis contaminata, Diplacodes trivialis, *Neurothemis fulvia, Onychothemis testacea, Palpopleura sexmaculata, *Potamarcha congener, *Rodothemis rufa, Rhyothemis variagata, *Tramea virginia, Zygonix iris.

That is a whopping 18 different species in my list.