Just around the corner - Lao PDR

On February 21 I had to go to Luang Prabang in Lao PDR for a meeting. In between reading papers for the meeting I popped into the woods close to the hotel. It was smack in the dry season, but I managed to find two species that I had not seen before, not in Vietnam and not anywhere else. The first was pretty Coeliccia dydima. This species might be confused with the similar C. cyanomelas. C. dydima is a common species in Thailand and Lao PDR, but has not been found yet in Vietnam. And maybe that is because it does not occur there. But I will keep on looking. It was nice to get some experience with it in neighboring Lao. I saw at least 10.
The other species was Aciagrion pallidum. This species  has been reported also from Vietnam, although I have not been able to find it yet, so likely it is localized and/or rare in there. It appears to be a dry season species, when it hides in dry forest and waits for the rains. The rufous abdomen is a good character. I saw only the one male.
Lastly, I also saw few Coeliccia poungyi poungyi, always a nice species to bump into. Here are a few record shots.

Here is the male of Coeliccia dydima. Note the limited extent of the blue on the abdomen tip and the large anterior dorsal markings on the thorax (in comparison to C. cyanomelas)

Here is the female. The pattern on S9 is a good feature.

And an immature male (note the color of the eyes). It is very yellow, not blue, and the dorsal markings on the form a pair of somewhat immature C. onoi like spots, not yet separated into two sets of two (meaning 4 separated spots in total). 

How about this? Beautiful, but inconspicuous, male Aciagrion pallidum.

Finally, Coeliccia poungyi poungyi, a female. Note the solid yellow abdomen tip.

And the exquisite male!

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.

A few hours in Vientiane, Laos and a new species for the Laotian list.

This Thursday I had a few hours to spare in Vientiane and took a cab to the outskirts of the town. Thank God the surroundings are not close to being as polluted as around Hanoi and I was able to find 38 species in a short time. Vientiane is about as far south as Ha Tinh in Vietnam, which is about the southern edge of my general research area (northern Vietnam). But its species are quite different, much more southern. There was a lot of overlap with the commoner species in Cat Tien National Park, for instance. I was happy to catch a Epophthalmia frontalis male. Yokoi & Souphanthong actually list 31 Macromiidae, 28 of them Macromia. Which is rather astounding. But anyway, I was happy with my frontalis. And I was able to take pictures of male Lestes elatus and female Ceriagrion cerinorubellum. I had seen both these species in Cat Tien, but had not seen these sexes. Below a few pictures. And another very common species in some inundated and apparently deserted rice fields was an Aciagrion. I had to go back to Ris (1911) and Fraser (1933) to find out what may be the differences between Aciagrion occidentale and A. borneese. The appendages look rather similar and the A. borneese I had from Da Nang had been eaten by vermin. But in the end the description of Fraser pointing out that S8 is blue with a black triangle on it in A. occidentale, whereas A. borneese has a broad dorsal black stripe over the whole segment, provided the clue. Photos from India confirm the pattern on A. occidentale, and I therefore conclude that the specimens I saw were A. borneese, on the premise that the pattern is consistent over the complete range of these species. Interestlingly Yokoi & Souphanthong do not list either of these species for Laos. A. borneese is a very common species in Thailand and that country is of course right opposite the river at Vientiane.

Let's start with the addition to the Laotian list, Aciagrion borneese. Note dorsally black S8 and S10, whereas S9 is marked by a thin blackish dorsal line.

Another male with the distinctive pattern

Female Ceriagrion cerinorubellum. Possible to confuse with C. auranticum because of the green eyes and orange-brown cranium. However, S3-7 are blackish above and blue-green laterally, not orange, and S9 misses the clear darker marking.

Lestes elatus female

And the male, which I had failed to find in Cat Tien.

And finally a fine male Epophthalmia frontalis

Aciagrion borneense - another cool little damsel

Wednesday September 10 I was for work in the city of Danang, visiting some communities on the outskirts. While traversing some former rice fields now covered in grass and puddles I noticed a small and slender blue damsel. A little later I saw several more, interacting in little territorial disputes amongst themselves and with Agriocnemis femina. I could catch one with my fingers and put it in an empty water bottle. In the evening, back at home in Hanoi, I could take some photos and identify it as Aciagrion borneese, a very common and widespread species, that has been recorded before in Vietnam, according to the IUCN information, but apparently recorded only rarely, although given the fact it is common and widely distributed from Indonesia to Thailand and Cambodia in disturbed habitats, it may be also widespread in the south of Vietnam. It is a distinctive species because of the reduced blue on S8 and S10, with blue dorsum to S9. The appendages are a close match with the drawings in Ris (1911), although slightly larger (abdomen 22 mm against 19 mm in the description).

Caught in a trap: Male Aciagrion borneense inside its plastic cage

The scanned insect

Close-up of the thorax and head

Dorsal view of S8-10 and appendages

The same in lateral view

Aciagrion approximans - no end to my problems*

*Adjusted on April 16, 2016, after communication with Oleg Kosterin. A. approximans has now been redescribed and takes precedence over A. tillyardi.

When checking for the umpteenth time the small pond next to the lodge in Cat Tien I noticed a small coenagrionid in the grass, freshly emerged. Although small and fresh damsels will not likely survive capture, it was clear this was something I had not seen before, so I decided to catch it and stick it under a glass in my room to harden. I am sort of glad I did, for when later checking the details, it became clear this was a small Aciagrion species with a concave posterior margin to the superior appendages. Sort of glad, as this is where the problems begin. As can be seen from the photos on Asia-Dragonfly and the discussion on the website of Dennis for Thailand, there are several species that are being claimed as A. tillyardi, the species that would be the species of choice for this little fellow. There are only a few Aciagrion with forked superior appendages. The larger A. migratum occurs in Vietnam too. Now, there is a purplish Aciagrion that occurs in Thailand, for instance, with elongate postocular spots connected by a bar across the occiput, so the complete feature is like one elongate bar across the dorsum of the head. And there is a blue species with rounder postocular spots. The appendages are apparently similar. Th original description of A. tillyardi in Laidlaw (1919) does not mention any purple tones, and nor does he mention blue for that matter. He speaks of narrow gray-blue ante-humeral bands (sic) and gray-olive sides. He does state that the head has "a linear gray-blue post-ocular mark on either side, joined by a fine transverse line of the same colour across the occiput." Not purple, but also no rounded postocular spots. He also states that segment 9-10 are gray-blue and S10 black, obviously a mistake. I assume he means that 8-9 are gray-blue. One wonders whether this description fits any of the species claimed to be A. tillyardi. Luckily, my specimen is teneral and therefore neither blue nor purple, but it does have elongate postocular markings. For the time being I claim this as A. tillyardi. It certainly is not any of the other species in the area.

The fresh tiny male Aciagrion approximans

Dorsal view of appendages

Dorso-lateral view of appendages

Dorsal view of head, showing elongate postocular markings, blacking prothorax (but blue frontal lobe) and blueish antehumerals, but note this is a very fresh specimen.

And we wait for some courageous researcher willing to dive into this genus and sort things out. I also hope to collect mature specimens later this year. Like the genus Heteragrion in South-America and so many other examples, it might be better to just discard all old descriptions based on a few specimens, now long turned into dust, where these descriptions do not provide enough detail or decent drawings. Sorry for the scientists of yore, who clearly did what they could under the circumstances and based on what was seen as proper scientific work. Sadly, it does not stand the test of time. Sacrilege! Yes, but sometimes it may be necessary to throw of the shackles of past inadequacies.

A few other Coenagrionids

In the same general area I encountered Paracercion v-nigrum several other interesting damselflies could be seen. Amongst these Aciagrion migratum, a species I had seen once at Tay Thien in Tam Dao and once in Huu Lien. In the same fields along the TL212 in southern Cao Bang Province this species could be seen in small numbers.

Aciagrion migratum, male, a beautiful slender damsel with forked superior appendage

The female of Aciagrion migratum

 Another species found in the same field was Paracercion melanotum. In fact, the blue line in the black humeral stripe is almost too prominent for this species, suggesting P. sexlienatum. However, shape of postocular spots, color of the eyes and apparent shape of the appendages point towards P. melanotum. After its presence was verified for Huu Lien and it likely also occurs in Van Long Nature Reserve, this is a third location, showing this species occurs over a wide area.

Male Paracercion melanotum

Finally, a species that always truly amazes, because the color of the male is so unbelievable plastic blue. Ceriagrion azureum, a large Ceriagrion, occurs sometimes in rice fields. The place where we had seen them last year in Ba Be National Park had been destroyed, so I was very happy to see this beautiful species in several places, both in northern Bac Kan Province, as at the same site where P. v-nigrum, P. melanotum and A. migratum were present in Cao Bang Province. Here around 10 individuals could be seen.

Copula of Ceriagrion azureum

The same copula

A different male. This is truly a stunning creature.

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

Aciagrion migratum

On August 24 we were checking a stream just outside Tam Dao National Park near Tay Thien. A blueish damsel caught the attention of Kameliya and she called me over. It was something different and still vaguely familiar. A slender damsel with rather longish abdomen. Checking it at home it had to be an Aciagrion species. That was a surprise, as I did not know these occurred in Viet Nam, although in retrospect, it was not that strange, as they are known from neighboring countries like Thailand and China. Oleg Kosterin was kind enough to give his views on it and then I knew why it had looked familiar: I knew it from Japan. It was Aciagrion migratum. Basically the bifid superior appendages indicate closely related A. tillyardi or A. migratum, but the shape of the postocular markings (more of a stripe in migratum and more two spots with a thin line between in tillyardi (thanks Oleg!) helps clinch the ID. Up to now I have only seen it once.

Aciagrion migratum, male

The same male, slightly different photo

Close-up of postocular markings

Showing the bifid appendages