Wednesday, 31 December 2014

Wrapping it up at Cat Tien

All in all it has been an amazing time at Cat Tien National Park again, bringing in plenty of new discoveries and showing what a treasure trove Vietnam really is, when it comes to Odonata. I saw about 270 in 2014 and there is definitely no end in sight, but most of my time is spent in the north. So these trips to the south are a rare treat and bring in loads of new experiences. For one, there is no real quiet season. Although in the north even now you can find dragons or damsels (just last week, on the 26th I had a female Megalestes micans in Sa Pa (yes, even at that height they hang on in the cold) that does not compare to the exciting hustle and bustle of the south. Here is a few more damsel pictures to wrap up adventures there.

Male of Argiocnemis rubescens, very common in November

And the immature female of Argiocnemis rubescens

Another species that was surprisingly common this time round was Onychargia atrocyana, here a male

But what was really a surprise was Rhinagrion hainanense. This is a male, although I also saw a female. Very similar R. yokoii has recently been shown to be a junior synonym of this species.

Diplacodes nebulosa - another mystery solved

Where is Diplacodes nebulosa? I asked myself that question often. I had seen it once on a trip to the Mekong Delta in wintertime. That was a work-related trip before we moved to Vietnam and I had never seen it since. Now the riddle was solved. Although the species has apparently been recorded in the north, it certainly has not been seen there by me. Now in Cat Tien I found it present in the dried out and grassy fishponds, where fresh specimens abounded. So, it can be very common in the south, but as a wintertime (dry-season) species. Adult males are grey with dark wingtips, which makes them easy to recognize. The female has a neat black-and-white pattern on the abdomen and thorax. Once known, also easy to recognize.

Female Diplacodes nebulosa with typical broad black dorsal stripe on abdomen and blackish thorax with light stripes.

An adult male, easy to recognize because of small size, blueish-grey colour and dark-brown wingtips.
Another male showing the distinctive wing pattern
And obelisking in the hot sun
Immature male showing the same abdominal pattern as the female, the same thorax pattern too, but the wing tips are already somewhat darkened.

Rhyothemis species from Cat Tien National Park

There are four species of Rhyothemis at Cat Tien, but R. triangularis was sadly absent and I therefore failed to get pictures of that lovely species once again. Other species were less common than they had been in July-August. I saw only a single R. plutonia.

Male Rhyothemis phyllis, a lovely species with reduced black-and-orange pattern on the inner wing.

R. plutonia is a fantastic species that looks pretty much black from a distance, but under close inspection reveals green and purple on the inner wings.
Finally, a female of R. phyllis. Possible to confuse with R. variegata, but black-and-yellow pattern much larger and extending far onto the outer wing on that species.

Neurothemis species at Cat Tien

In the north of Vietnam I bump into Neurothemis fulvia regularly. At Ba Be for instance it is really common. The other Neurothemis here is N. tullia, but I have here in the north only seen it at Van Long. Plus a lonely record of N. intermedia at Cuc Phuong of a single female. But at Cat Tien there are three common species. N. fulvia occurs all over the place. N. tullia is common especially at the fishponds. And Neurothemis fluctuans is a small red-winged species that I have not seen in the north, indeed I am not aware of any records in the north. During my visit in November I also saw a single female (again) of N. intermedia. Although apparently in Thailand for instance this can be a very common species, here I saw just a single specimen at a dried out former pond in open terrain. Maybe she had just sort of happened upon the place, a drifter. Below some shots of the Neurothemis species I took during the trip and a few shots of Brachythemis contaminata. That very common species is a possible pit-fall for female and immature N. fluctuans.

Let's begin with the male of Mrachythemis contaminata. The black middle line on the abdomen and the orange wing-pattern, darker near the middle, help identify. 
This is the female of B. contaminata. The blackish line along the dorsum of the abdomen is very obvious and absent in the Neurothemis species.
Female Neurothemis fluctuans. Note the dotted line close to the lateral carina and only a very thin line over the dorsal carina on the abdomen.

In dorsal view, the dotted line located just short of at the very edge of each segment.

Another female showing the typical dotted line on the abdomen. This specimen also with darkened wingtips.
The immature male showing the same, but somewhat more pronounced abdominal pattern and the wing pattern of the adult male in orange brown.
The mature male, with abdominal pattern obscured by dark reddish colour and now deep red wings, with the transparent tips to the hind wings extending along the posterior edge towards the middle.

In comparison, male N. fulvia, with transparent tips reduced to the apex of the wing only, not extending along the posterior edge.

Another male N. fulvia. The transparent apex starts halfway the pterostigma.

Female N. intermedia, with typical broad uninterrupted lateral line and dark humeral stripe

Female N. tullia, smallish species with dark brown and white wing pattern.

The male of which has extensive black on inner wings and whitish-grey outer wings.

Tuesday, 30 December 2014

Prodasineura coerulescens - another Prodasineura

One species that was on the Cat Tien list already, but that we just could not find, was Prodasineura coerulescens. On November 18 I decided that before we were going home I should at least give the Dong Nai river a closer look. Until that time we had largely ignored it. Yes, I know, silly. So, when a blue damselfly hovered just above the surface in typical Prodasineura fashion I knew that mystery was solved. Prodasineura coerulescens does occur at Cat Tien and it favors the rapid parts of the main river. It is a very nice damsel, as most Prodasineura in fact are. And a cool new species. It is known from both Thailand and southern Vietnam, apparently absent from Lao DPR and Cambodia, but maybe it is just awaiting discovery. I saw about 4 males. P. laidlawi is also known from Vietnam and similarly blue, but it has more extensive blue on S9 and a different pattern on the top of the head and the prothorax.

Prodasineura coerulescens, male, perched above the river

And another, hovering above the current

Heliaeschna uninervulata - Swarming at Cat Tien

On November 17 we were checking the road from the lodge to the fishponds in an open, disturbed, area, with some forest and shrub cover. Close to dusk, we were looking for Gynacantha. As luck would have it, a species appeared in good numbers, with several score dancing around. But not so lucky, they stayed quite high. Kameliya discovered a place where they were flying somewhat lower and I was able to net two females. In hand, they had very broad leaf-like appendages. But my mind was set on Gynacantha, so it did not occur to me this could be something else. It was only after Oleg Kosterin (thank you Oleg!) responded to a later email by me, that it dawned on me that this was a Heliaeschna. Venation in the wing made it clear it was H. uninervulata, a species that had been reported from Vietnam before (1953, Lieftinck), but otherwise apparently had gone unnoticed. It occurs widely over south-east Asia, so it probably occurs more commonly.

Heliaeschna uninervulata, female. In coloration and appearance rather Gynacantha-like. Note the single cross-vein in the median space.
Dorsal view of the frons
Facial pattern, rather simple
The distinctive leaf-shaped appendages

Sunday, 28 December 2014

Two more Lestidae from Cat Tien

During my little excursion to Cat Tien, I was able to finally find Orolestes octomaculatus. That was very welcome. James had found one in the lodge, but I had not been able to replicate that record and felt hopelessly left out. This time round I was more lucky. First we found a freshly emerged female in the flooded excavations on the way to the fishponds. Then I found a female smack in the middle of the forest, and finally several males at ponds close to the bird lake trail. It is an easy species to recognize. The female in hand by the 5-6 large teeth on the ovipositor and the male by the 8 spots on the wing.
The other Lestidae I ran into, was a female Lestes elatus, which I found at the fishponds. Luckily an easy species to recognize on account of its patterning. Also apparently common in all sorts of disturbed habitats. I found only one, but at least we know it is there. Hopefully also males next time.

Lestes elatus, a female photographed from some distance

The same female in hand. I am sorry about the prominent finger, but if you check the print, you can see it is me. The pattern on S8-9 is very typical.

Orolestes octomaculatus, not a good photo and with flash, but you can see the typical double-dot pattern on all wings.

Another male, again a little hasty when taking the picture

Female of Orolestes octomaculatus, note the rather different, plain, coloration of S8-9 when compared to female O. selysi (see that post)
Note the large teeth on the ovipositor (same female as in previous picture)

Tetrathemis irregularis hyalina - the second Tetrathemis

During our second survey of Cat Tien National Park in November we encountered a great many of the lovely little Tetrathemis irregularis hyalina. This species had already been reported from Cat Tien and it was one of very few species reported and not yet found in the first survey and by James Holden. In August I did see just a couple of Tetrathemis platyptera, or so I thought. That made me somewhat skeptical concerning the occurrence of T. irregularis hyalina, but both species do occur in the same habitat. So, it should not have come as a surprise when we saw them all over the place this time round. Clearly it is absent during the wet season. We saw them along moderate slow and muddy streams and at pond and puddles in the forest. There was also one at the fishponds, so it tolerates a high variety of habitat. Although I was pretty sure I saw amber in the wings of the few females I saw in August, conditions were terrible, in the rain. Checking the photos, it seems that the size of the abdominal markings is in favor of T. irregularis hyalina, as is the color of the eyes. I apologize and correct myself...

Although very similar to T. platyptera, T. irregularis hyalina has completely clear wing bases (with large amber basal spots in T. platyptera)
Another male, perched by a pond
The neat facial pattern with pale-yellow anteclypeus and postclypeus and sides of antefrons.
The female of T. irregularis hyalina, with only limited markings on the abdomen compared to female T. platyptera.

Tuesday, 23 December 2014

Another name change: Idionyx claudia, I guess she had to go

Keith Wilson already pointed out to me that Idionyx claudia does not have short antehumeral stripes and that he therefore could not believe that the species I found in Xuan Son late May was in fact this species. I failed to update the blog, also because I left some uncertainty in my entry as to the specific identity. But I have had already for a while a suspicion that it is a species described by Asahina in his work on Thai Odonata, Idionyx selysi. The citron yellow anteclypeus and labrum combined with the short yellow antehumerals, the brownish suffusion to the wings in addition to the amber basis, the simple vulvar lamina and the dent in the posterior edge of the second dark lateral stripe towards its dorsal end all point to this species, although the legs are possibly oddly dark and the anal loop has too many cells (but this is also the case for all female I. thailandica that I scanned in comparison with Asahina's description. So, I changed the entry and will look for the male when spring comes.

Bayadera revisited

About a week ago I met with Phan Quoc Toan, who is working on his thesis in Japan, but happened to be visiting. He has been doing quite a bit of work on the confusing group of Bayadera. I had lent him the few specimens I had and the bad news is that he pointed out several mistakes I had made in my enthusiasm and based on the little correct information there is. Toan has looked at many specimens from collections and it is clear I had to revise some of the blog entries on the genus. Bayadera nephelopennis from Tam Dao is not that species, but is in fact Bayadera bidentata. Coincidentally, Karube had already published that species for Tam Dao. The few Bayadera bidentata I had collected or photographed, from Yen Bai and Sapa, are in fact Bayadera hyalina. And the one fresh specimen from Lai Chau in April might in fact be Bayadera strigata. I am indebted to Toan for sorting this out and today will change the earlier entries. The good news for me is that although I lost one species, I gained two!

Copera number 3

On November 15 I was checking some ponds in the forest along the main road in Cat Tien National Park. A truly dark place it was, but with some small sunny patches where the sun peeked through the foliage. I noticed a Copera there with yellow legs, but only very little white on the abdomen tip. After I caught it, it became obvious it had very different appendages from C. marginipes or C. vittata. The latter species in the north of Vietnam also has yellowish legs, but here in the south the legs are truly very orange. So, obviously it was not C. vittata and it also was not C. marginipes. I knew of another species in South-East Asia, C. chantaburii, but was not aware of its occurrence in Vietnam. Checking the literature I learned two things: it indeed was C. chantaburii and that species is known from southern Vietnam. But to me it was new. Interestingly, it occurred side by side with both C. marginipes and C. vittata. Below photos were all taken along the same 4 metres or so of pool edge.

This is Copera chantaburii. Note is has appendages of approximate the same length both superior and inferior. S8-9 are completely dark dorsally. Nevertheless, with its yellow legs easily mistaken for C. marginipes.

Close up of the dorsal pattern of another male

And the interesting appendages, all equal in length

Copera marginipes has S9 all white and S8 extensively white on the posterior half. The superior appendages are very small, but the inferiors are very large.
And although in the north confusingly similar in colour, here C. vittata sports very orange, almost red legs. It has less white on the abdominal tip, with most of S9 white, but S8 black. The superior appendages reach to halfway of the inferiors.

Coeliccia sp becomes blue*

*This entry was adjusted early 2017. It is now clear that there are two closely related species in Vietnam and neighboring countries. The species is Cat Tien is not C. kazukoae, but a soon to be published different species.

My earlier visit to Cat Tien (see entry from August) had turned up quite a few Coeliccia sp., some of which looked pretty much mature and were still yellow and brown. I wondered if it might be a distinct species from C. megumi after all. Well, I was proved wrong during our November visit to Cat Tien. In the much drier forest I ran into quite a few adult males and a few females, now no longer dispersed in the forest, but hanging from the tips of leaves along small streams. And they were invariably blueish (apart from a fe immature ones inside the forest), but in hand had identical features. Here a few shots of the adult, which apparently takes quite a while to attain full colours.

Male of Coeliccia sp., note also the colour of the eyes.
And the female, a little whitish under the flash, a necessary evil in these dark places
A different male, note the longer greenish-blue line over the humeral suture in this individual.
Close-up of thorax pattern and eyes.
Close up of the appendages.