Monday, 30 September 2013

Two Paracercion or Lilysquatter species*

To continue on the subject of Van Long Nature Reserve, there are two Paracercion species there that can commonly be observed on the water plants. There is another, more robust if similarly looking species around, Pseudagrion australasiae, but this entry is on Paracercion. The one species is Paracercion calamorum, which I have also seen in Cuc Phuong and Ba Be National Parks. Seemingly it is not a rare species. The other is Paracercion malayanum, which I have not seen elsewhere, but Sebastien also mentions its status is unclear in Viet Nam and has only seen it in...indeed, Van Long. The female is rather different and reminiscent of the bulkier Pseudagrion species.

*Subsequently, it became clear that the identity of this Paracercion is not as straightforward. For the time being it is better to treat it as P. cf. melanotum, although the female seems quite different in coloration. See later posts on this subject.

Paracercion cf. melanotum, male, doing what it does best, squatting on lilies

Another male in pretty much the same pose

Paracercion cf. melanotum, female

Another female
Paracercion calamorum, male, in a bush on the edge of the wetland

And another male, squatting on a lily

Paracercion calamorum, female

Another female on the shrubbery

Macrodiplax cora

While on the subject of Van Long Nature Reserve, there were a few other interesting species, one of which I only saw the female of. In fact, when I spotted it sitting on the tip of some maize plants I was puzzled a bit, as I could not place it and the thorax pattern reminded me of Sympetrum species. And of course it will be clear to the reader that there are no Sympetrum species in this part of Viet Nam. Later I was able to find the answer. It is none other than Macrodiplax cora, Cora's Pennant. It is interesting that, as can be seen in the photo, it has green eggs. This is another very wide spread species, that has even reached South Africa.

Macrodiplax cora, female, still far away and Sympetrum like

A lot closer, another female, note green eggs

Urothemis signata

When visiting the lowland marshes of Van Long Nature Reserve at the first weekend of September I had a chance to acquaint myself with some apparently common marshland species that until then I had not seen. One of these was robust and red Urothemis signata. I found the males in low numbers sitting on the tips of stalks in the water, and females nearby amongst the fields or in the top of the trees. There they could be identified easily on the basis of the wing markings, characterized by a dark dot in an amber field. It is a widely spread species, with several subspecies, occurring from China to Pakistan to Borneo. It is only fitting that it also occurs in Viet Nam.

Urothemis signata, male

Urothemis signata, female

Another female in hand, showing robust vulvar lamina and the wing markings

And this is what she looks like from underneath

Sunday, 29 September 2013

Noguchiphaea yoshikoae

In August I had seen several females of Noguchiphaea yoshikoae at Tam Dao, close to the resort. I saw only teneral females then, so here at least was a species that I might still bump into this late in the season. Indeed, I was happily surprised to see 1 or 2 males today and one female. One of the males was holding territory over a puddle by the side of the stream, whereas the female was seen inside the forest a little further removed from the stream. It is a very nice species.

Noguchiphaea yoshikoae, male

And Noguchiphaea yoshikoae, female, a harder shot up in the tree

Euphaea guerini vs. masoni

September 29 I went to Tam Dao. Like everywhere, the number of stream dragonflies has fallen drastically and it was hard work to find something. At last I located two dark Euphaea specimen. Now, I already did an entry on Euphaea, but it is in for some revision, I am afraid. The first specimen today was rather straightforward and in the hand showed extensive blueish shine to the underwing. This is also very visible in the photos taken with flash. The second was very brownish and I could not see any blue shine, nor is this visible on the photos I took, but in hand it showed the same blue luster to the underside of the hindwing. Nevertheless, I could have sworn...

So when I got home I had a look at the one specimen I had collected earlier this year. I also took the article by Van Tol and Rozendaal (1995) and compared. Now I was in for a shock. Although I had simplified matters before, focusing on the shine to the wing and the amount of translucent tip to the hindwing, in fact Van Tol & Rozendaal give a few straightforward structural differences between E. guerini and E. masoni. Guerini has a tuft of long hairs at the base of S9 and has ridges on the lateral corners of the vesicle. Well, none of the specimens in the photos has hairs on S9 and the specimen in my collection certainly does not, nor does is have the ridges on the vesicle. So, irrespective the blueish shine, it is E. masoni. That means that for the time being both the specimens from Tam Dao and those from Ba Be have to be registered as E. masoni. Next year I will study the Ba Be specimens in hand too.

The brown-looking specimen, Euphaea masoni, male

Different male, with flash clear blue shine

Ventro-lateral view of S2, showing smooth vesicle
Ventral view of vesicle, very smooth

S9 without a trace of hair

Saturday, 28 September 2013

Whispy things

If you look closely in grassy wet places, you cannot miss them, but if you do not look closely, you may well overlook them, the Whisps. Two species are especially common in Northern Vietnam (and in many other places): Agriocnemis pygmaea and A. femina. They also look a lot alike. A. pygmaea prefers grassy verges of streaming water, whereas A. femina is more commonly represented in wet, inundated grassland. But they can often be seen side by side. The best distinguishing feature are the long lower appendages of A. femina, and that species becomes whiter with pruinosity than A. pygmaea.

Very white Agriocnemis femina, male, showing long appendages

About as white as they get, Agriocnemis pygmaea, male, showing absence of long lower appendages

Another pruinose male A. femina

Less pruinose, but clearly long appendages, A. femina, male

Non-pruinose A. pygmaea, male
Non-pruinose A. femina, male

Female Agriocnemis femina
Same female in close-up, showing dark markings on prothorax

Acisoma panorpoides

The Grizzled Pintail is a common species, occurring from the Southern Tip of Africa all through Southern Asia up to Japan. But that is quite alright, as it is a little fun species. It likes muddy grassy swamps, where it lives the life of a little aggressor, devouring little insects, but also for instance damsels. While I was observing a male at Xuan Son I caught a glimpse of a Agriocnemis pygmaea from the corner of my eye. So did the Pintail.

Acisoma panorpoides, male

Eating the unfortunate Agriocnemis pygmaea male

Acisoma panorpoides, female

Ischnura carpentieri and Ischnura aurora

September is drawing to a close, but the weather was warm and sunny, so September 28 I decided to drive to Xuan Son National Park. I had no idea what it would be like, they have a website, but it did not seem to be maintained. Well, that was not the only thing that had not been maintained for a while. The gate was open and not a sole in sight (later there was) and near the office building, nobody and the buildings seemingly only partially in use. I drove on to the school building and other buildings (a small hospital and I guess lodging, the hospital not in use and the lodging used by Water Buffalo. On the other hand, a massive concrete road through the reserve and after walking the trail near the school over the hill, the next valley and hamlets were also being connected by a massive road that had been freshly cut through the forest. All not boding to well. I did not find bigger streams in the reserve while I was there, but I checked the rice fields and their borders. Many Crocothemis servilia, Diplacodes trivialis, Orthetrum sabina and O. pruinosum, but also Acisoma Panorpoides, and several damsels. My attention was caught by two different damsels with orange abdomen and blue tip, both seemingly forktails (Ischnura), one larger and one smaller. The larger one (of which I saw only two) was a member of the Ischnura rufostigma group. There is a lot of confusion about the four members of the group and I do not have the Asahina 1991 paper. That may be lucky, as apparently that only increased the confusion. But be that as it may, the dorsum of S8 is all blue and therefore I will categorize it for the time being as I. carpentieri. The other, smaller, species was more common and I saw it in several locations. This is Ischnura aurora, a pretty thing indeed.

Ischnura carpentieri, male (Or I. rufostigma, for the lumpers)

Ischnura aurora, male

A different male

Ischnura aurora, female

And another female

Thursday, 26 September 2013

Coeliccia ambigua

In the same paper in which Asahina described the two forms of Indocnemis orang, he also described a new species of Coeliccia, C. ambigua. In the blog of Sebastien Delonglee you can read a discussion on the ambiguity of the genus. Is it Coeliccia or Indocnemis? No need to repeat that discussion here. Suffice it to say that I ran into this lovely damselfly in August at Tay Thien, Tam Dao National Park, rather deep inside the forest at an altitude of about 300 m asl. It was a darkish day, and I failed to make proper photos, I am sorry. But for the time being, this will have to do, as I saw it only once.

Coeliccia ambigua, male

Appendages in lateral view

Indocnemis orang

Asahina (1997) describes two forms of Indocnemis orang. The first was originally described by Foerster in 1907 as Trichocnemis orang. The second form (forma kempi) was described by Laidlaw in 1917 as Indocnemis kempi. In 1985 Asahina lumped them, but in 1997 he writes "Now I am changing my previous idea (1985a), in which kempi (1917) was synonymized with orang (1907), though the former was recognized as a large-sized form of the latter." He then discusses I. orang based on specimens from Cuc Phuong and I. orang, forma kempi, based on specimens from Tam Dao. These belong to the same species, according to Asahina, based on the form of the penile organ.
Indeed, when I ran into a smaller version of I. orang in Cuc Phuong, with a different thorax pattern, I first thought it would be a different species from the I. orang I know from Ba Vi and Tam Dao. For the time being, let's go with Asahina's interpretation.

This is a spectacular species of forested streams, where males occupy territories on large wet rocks and boulders. Below some photos of both forms.

Indocnemis orang, male from Cuc Phuong. Note reduced thoracic stripes.

Indocnemis orang, f. kempi, from Tam Dao

I. orang, f. kempi from Tam Dao

And another male from Tam Dao

Female I. orang, f. kempi (presumably) from Tam Dao

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

Wednesday, 25 September 2013

Agriocnemis lacteola

One striking little whisp is Agriocnemis lacteola. Like its brothers A. femina and A. pygmaea (both very common) it is not a rare species, although not as common as these other little whispy things. Talk about small! At least the almost pure white A. lacteola adult male catches the eye when it flies slowly from grass stalk to grass stalk on its search for even smaller prey. The females are much harder to recognize as they shade from all pinkish to greenish and look rather different from the males. I found it at Ba Be National Park (a few) and very commonly at Van Long Nature Reserve.

Agriocnemis lacteola, male

Another male

The greenish female

And the pinkish immature female