Wednesday, 18 December 2013

Onychargia atrocyana

This weekend I was on a mission in the Mekong Delta. And I know that I said I would be back next year, but when visiting the a Fish Breeding Center (with Pantala flavescens and plenty of Brachythemis contaminata), I plucked a small blackish damsel from a bush near the entrance. A few quick and dirty shots with the iPad, and I released it again. It is a species that undoubtedly is common on spring and early summer, even in the north, but that I had as yet failed to see: Onychargia atrocyana. So, even if the photos are terrible, I would like to share this with you! (Until next year I can replace these with better pics).

Onychargia atrocyana, male

And the same male ventrally

Wednesday, 11 December 2013

Prodasineura autumnalis

Out of three Prodasineura species mentioned in Do & Dang, there is one that even based on the scarce available material for Vietnam is widespread and this is the rather drab Prodasineura autumnalis. I have seen it all over the place, along better quality and lesser quality small streams in or near hills, at least when there is some wood along them. You see a lot of females too and often tandems. They hover readily above the water or hang from the tips of snags and leaves. The males are blackish all over, but the females have a nice stripy pajama. This may well be the last entry for this year. Coming weekend I have to work and thereafter I will be elsewhere for a while. But mind you, in February this blog will be filled with new entries with a vengeance.

Prodasineura autumnalis, male

Prodasineura autumnalis, female, far away shot. As is so often the case, no good photos of the more common species.

Prodasineura autumnalis, immature male

Tuesday, 10 December 2013

Paracercion continued again

Rory Dow was kind enough to provide photos of Paracercion malayanum from Java deposited in the collection at Naturalis in Leiden (Netherlands). Below the posterior view, please compare that to those in the previous message on the subject, and also the lateral view. I include with it the lateral views of specimen from Huu Lien and Van Long published earlier, to avoid that the reader will have to scroll too much. Do you not agree that there is rather great likeness between the three?

"Paracercion malayanum" from Java

Likewise, from Java

P. melanotum from Huu Lien

P. "melanotum" from Van Long

Sunday, 8 December 2013

December 8, Xuan Son in the winter sun

This Sunday, I drove to Xuan Son, to see what has changed since I last visited. Like in Huu Lien, water level had dropped, but the good streams were still good. Here too about 30 species for the day, but numbers for most were down. Coeliccia sasamotoi was the exception, being very much in evidence all over the place. What is interesting is that several species recorded for Huu Lien in summer, but completely absent during all our visits this November / December were still commonly flying at Xuan Son. Aristocypha fenestrella and Matrona basilaris were easily found. Also Euphaea masoni, only seen during our first visit to Huu Lien a month ago and not since, was still about in small numbers. What makes them stay on here?

I bumped into the following species: Matrona basilaris, M. taoi, Vestalis gracilis, Neurobasis chinensis, Atrocalopteryx coomani, Vestalaria miao, Noguchiphaea yoshikoae, Heliocypha perforata, Aristocypha fenestrella, R. "arguta" (I took pictures of several in hand, with hardly any orange on S9-10 to quite a bit), Euphaea masoni, Agriocnemis femina, Ceriagrion auranticum, C. fallax, Pseudagrion pruinosum, Coeliccia onoi, C. scutellum, C. sasamotoi, Indocnemis orang, Copera marginipes, C. vittata (I must have overlooked it before), Boyeria karubei, Orthetrum sabina, O. pruinosum, O. glaucum, Diplacodes trivialis, Neurothemis fulvia, Palpopleura sexmaculata, Crocothemis servilia, Trithemis festiva, T. aurora.

Old male Euphaea masoni

Another male with hole in wing

Matrona basilaris, male, was still common

Matrona basilaris, female

Atrocalopteryx coomani, male

Matrona taoi, male, only one and damaged male around

Pretty Coeliccia sasamotoi, male

Ceriagrion fallax, male

One of several captured Rhinocypha cf. arguta, with at least some orange on S9-10.

Very nice male Copera vittata, overlooked previously?

7 december at Huu Lien

We visited Huu Lien on the 7th to find the female of the "Pseudagrion". It was not too warm and not too sunny, but it was a good day. Clearly numbers were dropping and we only saw about 30 species, but hey, it is December. No Atrocalopteryx species, but supercool Labrogomphus torvus was still around. Water levels had dropped and some places had dried up already.

Much nicer sitting like this, than in hand: Labrogomphus torvus, male

The same male, after it chased a butterfly and came back

Paracercion continued

We now have had several posts on (Para)cercion malayanum en P. melanotum. Originally I was under the assumption that the species at Van Long, with females similar to P. malayanum in Thailand, was P. malayanum. This is also how Sebastien published it on his blog. Subsequent comparison of the appendages with males from Huu Lien made it look conveniently different, if closely related. I then found a typical P. melanotum female at Huu Lien. Put this together, then we have a different species at Van Long, similar to P. malayanum. However, the two males I collected the other day in posterior view are rather different from my first specimen from Van Long and in fact are very similar to P. melanotum. What is more, Rory Dow was kind enough to send me photos of posterior view of P. malayanum from Java. It looks suspiciously similar (to both the new specimens from Van Long and to that of Huu Lien.
It makes one wonder whether P. malayanum and P. melanotum are truly different. The photos from Thailand show males with wider blue stripes on the thorax (antehumeral), otherwise look very similar. The side view of specimens from Huu Lien and Van Long again is almost the same and goes well with the Java specimen. The females are rather different, but I have a female from Van Long with in fact a set of antehumeral black lines not unlike P. melanotum. Anyway, until I have close-ups of the prothorax of the females at Van Long (next year), we do not know if they are structurally different or similar to P. melanotum. For the time being I will consider the Van Long species as P. cf melanotum and the Huu Lien one as P. melanotum. P. malayanum may or may not occur in Vietnam, but I have difficulty proving it.

Here is the Huu Lien posterior view once more. With it is the new Van Long posterior view. If Rory will give permission, maybe I can add the Java photos too.

Huu Lien P. melanotum

Van Long new specimen Paracercion sp.

Saturday, 7 December 2013

The female Paracercion ambiguum from Huu Lien*

*This post adjusted after publication of Paracercion ambiguum

This December 7 we went once more to Huu Lien, battling the traffic on "Highway" 1 and once again surviving. The objective was again to find the female of Paracercion ambiguum. The sun was only remotely present; it was rather misty and later on cloudy. We also got the distinct impression that numbers had dropped drastically. But I was in luck. I noticed a female damsel sitting on a stalk of grass emerging from the reservoir right by the grassy edge and was able to catch it. It was rather different from the females of P. microcephalum from last week. In fact, it had the sides of the thorax like the male, same pattern, but different colors. It was slightly larger than the male, with similar postocular spots, but the shoulder stripe was very Paracercion-esk. Close-up of the prothorax showed that it lacks the typical "horns" of Pseudagrion. So, is this not Pseudagrion after all, than what is it, as the male shows characteristics not really in line with Paracercion!

First some pictures of the female:

The female of Paracercion ambiguum, at last!

Close-up of the thorax. Note the same distinctive marking along the interpleural suture as in the male, the large postocular spots, but also the double light line along the humeral suture.

Now let's have a look at some other Pseudagrion prothorax and compare them with our specimen

Prothorax of female P. microcephalum, note the distinctive ridge and horns along the posterior edge.

In female P. rubriceps these are equally distinctive

Whereas in female P. spencei they are clearly visible, if not as large

But this distinctive Pseudagrion feature is missing from our species.

Here is an additional close-up of the ovipositor.

Thursday, 5 December 2013

Lyriothemis bivittata

Another species I still have to publish here is Lyriothemis bivittata. This is a very interesting dragonfly, because apparently it breeds in tree holes and also because although it has a wide distribution, it is said not to be recorded very often. It is known from Vietnam, but here also said to be uncommon. In fact, I have seen it in these few months here in Cuc Phuong, in Ba Be, in Ba Vi and in Tam Dao, so it really is not that rare, just never common. You see one here, one there, never several. And up to now I have just taken shabby pictures. I have seen it from May to August, but not after August 18. Next year I promise to take better pics. This is a striking libellulid, with bright orange-red abdomen and two big yellow spots on the side of the thorax. That goes for both males and females. Below are females.

Lyriothemis bivittata, female

Another female

Wednesday, 4 December 2013

Pseudagrion microcephalum females

Last weekend we spent several hours trying to catch the female of the new Pseudagrion species, but to no avail. Once my net got stuck on a thorny bush, once a female flew off, but two I caught after all but swimming after them. However, there were also males P. microcephalum in the area and the two females that I caught were not in tandem, not directly associated with P. species. And after studying them they are either very similar to female P. microcephalum, or they are in fact P. microcephalum. Right now I have no reason to believe they are anything else. I have one more weekend to go and the sun is out, so who knows, but for now, these are P. microcephalum. Very different from each other in coloration, the one brownish, the other bluish, but otherwise, the same.

Pseudagrion microcephalum female, blueish, mature?

The same female in close-up

Another female, brownish, immature?

The same in close-up

Monday, 2 December 2013

Aciagrion migratum - no Prodasineura after all

On December 1 in Huu Lien I noticed a thin damsel hovering over the stream like Prodasineura autumnalis tends to do. At first I therefore suggested it might be something similar, but Rory Dow pointed out it had to be a Coenagrionid (thanks Rory) related to Ischnura, on behalf of the spine on the sternum of S8. That pointed me to Aciagrion and then I remembered that Aciagrion migratum passes through the winter as imago, but only gets its blueish color in spring. How exciting, the second record for Vietnam, but undoubtedly it is just under recorded.

Aciagrion migratum, female winter type

The same female

And in hand 

Close-up of the ovipositor and S8, showing clearly the apical spine on the sternum

Paracercion melanotum - verified!

Today at Huu Lien was successful in that I was able to verify the presence of Paracercion melanotum, not malayanum. I could not catch any males, but luckily I found a female in the grass along the reservoir. Not only has it got the distinctive stripe pattern in the dorsum and along the humeral suture, it also has the distinctive square bite out of the posterior edge of the prothorax! Now, this species has been recorded by Asahina (as sexlineatum), but as this was in southern Vietnam, that makes you wonder about malayanum. Having studied malayanum op close in relation to this, it seems that that species surely belongs in Paracercion, but who am I… Anyway, this is a definite melanotum!

Paracercion melanotum, typical triple line on dorsum and along humeral suture and note that posterior edge!

Paracercion melanotum, female

Sunday, 1 December 2013

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

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 female. For the time being I put it in the books as P. 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. See below:

Planaeschna guentherpetersi, female

And scanned

Face in frontal view

For comparison, the female from Xuan Son

And in hand, female from Xuan Son