Thursday, 23 July 2015

Nesoxenia lineata - new for Vietnam

July 23 I received a message from James Holden. He is currently surveying Odonata in Cat Tien National Park. He alerted me to a small Lathrecista asiatica-like dragonfly that was not just smaller, but had very different venation. Could I help?

When I checked my earlier post on Lathrecista, I noticed to my excitement and shame that I had included there a photo of exactly the same species James had now found, caught by me on August 5 last year.

Superficially the two species are very similar, but the venation is very different. The smaller species (James measured 27mm total length) has two rows of cells between the cubital space and the wing margin in the hind wing. It has a free triangle in the hind wing, but in the fore wing the triangle is 2-celled and the sub triangle 3-celled. There are two bridge cross veins in both wings. And amazingly, there is no anal loop in the hind wing. These characters fit very well Nesoxenia lineata, but that species has distinctive thoracic markings. I have found no pictures with the extensive pruinosity of both mine and James' specimen. And N. lineata is apparently somewhat larger.

Rory Dow commented that the venation indeed points to N. lineata. He also mentioned that he would not be surprised if the heavy pruinosity is either the result of age or of geographical variation. And that the size is close enough, given the likely small sample on which the size of the species is probably based in the literature.

Yesterday I received another photo from James, this time of a female. This female too seems lightly pruinose, but the underlying pattern of the thorax is clearly visible and fits N. lineata like a glove.

N. lineata has been recorded in Thailand, but has never been recorded from Vietnam. But judging from both my own and James' observations, it is regular at Cat Tien. Because both our males and the female display heavier pruinosity than usual, this may be a peculiarity of the Cat Tien population.

The possible Nesoxenia caught by James. Note the venation characters. Red extends onto S9. 

This is Lahtrecista asiatica. Much larger, distinct anal loop, 4 rows of cells between cubital space and wing margin in hind wing, only 1 bridge cross vein
My specimen of last year August, showing obscured thoracic pattern.

Blow-up of hamule, strongly hooked
Photo by James, including his hand, of female N. lineata, showing the typical thoracic pattern of the species

Tuesday, 21 July 2015

Anisogomphus maacki - new for Vietnam

June 18 I noticed a rocky stream next to the road that runs just north of Pia Oac and connects Cao Bang to Ha Giang. I decided to climb down to it and give it a go. After a short while surveying I noticed a gomphid perched on the rocks in the stream that first reminded me of Stylurus, because of the wide expansion of S8-9 and the markings on it. But in hand I noticed the typical Anisogomphus spines on the femora. A bit at a loss I checked Chao and found out that it was just that. Anisogomphus maacki, a species that years ago I had also seen in Japan.

This is noteworthy, its occurrence in Vietnam, because its occurrence in the south of China, although reported, has been questioned. The species has a wide distribution, ranging from Nepal to Japan, but generally is believed to be a more northern type of gomphid.

That is why it was an even larger surprise that I ran into it again on June 23 just below Sa Pa in Lao Cai. Which means that it cannot be that rare and must be rather widespread. Here too I found it at a rocky stream in relatively open terrain. At least 7 males were present.

There are several Anisogomphus species in Vietnam. Besides the relatively uncommon Anisogomphus koxingai that also includes Anisogomphus tamdaoensis, which was placed in the wrong, but closely related genus Merogomphus originally, but now placed in Anisogomphus. In fact, it would not surprise me if it would turn out to be a junior synonym of Anisogomphus pinratani from Thailand. The two species are very similar, to say the least. Anisogomphus tamdaoensis is a widespread and common species. And then there is the Anisogomphus sp. novum that I first saw at Pia Oac. As a matter of fact I saw a female at the same place as where I first saw Anisogomphus maacki. That location is actually not that far from where I saw this unknown species first (about 40-50km).

Male Anisogomphus maacki, with widely expanded S7-9 and big yellow markings, although quite reduced on S9.

Another shot of the same individual from Cao Bang
Close-up of the thorax and head of a different specimen

S7-10 and appendages in dorsal view. This specimen even less yellow on S9

Face of the same second specimen from Cao Bang

One of the males from Lao Cai. Note the large spines on the distal part of the femur of the last pair of legs.

S7-10 and appendages in dorsal view, this specimen clearly with more yellow on S9

Scan of the Lao Cai specimen

Saturday, 18 July 2015

Philoganga revisited - the case for several species

*Text slightly adjusted on August 19, 2019. The reference to P. robusta being sometimes pruinose may be mistaken, it could just as well be P. vetusta. The species incertae in fact is P. montana and has been recorded also in 2018 in Cao Bang (male and female).

I already posted in the past on Philoganga. At the time I discussed the occurrence of whiter specimens presumably P. robusta, if we consider that the colour pattern of the specimens is a reliable indicator of specific identity.

This spring I noticed in early May that Philoganga were quite common on Mau Son mountain in Lang Son Province. The thing was that they were consistently pale bluish-green on the abdomen and none where orange. This triggered me in collecting more Philoganga this year for comparison. Although sample size is still small, it supports the impression in the field from larger numbers of specimens that Mau Son specimens were larger and more robust on average than P. vetusta.

The issue is complicated, because older males seem to sometimes develop pruinosity that makes them appear whitish. This has not been established amongst the population of P. robusta of Mau Son. There is also some variability in size of specimens, especially, it would seem, in P. vestusta.

Wilson & Reels (2001) reviewed the literature on Chinese records of Philoganga. There is no need to repeat here their excellent overview of mistakes and inconsistencies in the records of these very similar species. What they did conclude was that some characteristics mentioned in the literature to separate the species were clearly erroneous. The number of cells in between the wing margin and 1A is such a character. Indeed, I could find no consistent difference between what I consider P. vetusta and P. robusta in this character.

Wilson & Reels do suggest that the presence or absence of an antehumeral stripe could be of help. I found that the antehumeral may be somewhat more prominent in P. robusta, but that it can also be prominent in P. vetusta. Prominence seems to be related to age, with older specimens becoming darker on the dorsum of the synthorax with reduced or faded antehumeral.

The number of antenodal cross veins has also been mentioned as possible identification character. This was already pointed out by Wilson & Reels as invalid. Indeed, I counted 12-14 antenodals in definite P. vetusta (N=4) and 13-15 in P. robusta (N=3). Likewise postnodals range from 30-31 in P. vetusta to 29-34 in P. robusta. I have found no differences either for the few females I collected, but it is hard to draw conclusions, as the specific identity is difficult to prove, although one was caught in tandem with P. vetusta male and thus presumably that species

Wilson & Reels mentions that abdomen size of specimens from Hainan for P. robusta was 61.0 mm. My specimens are slightly smaller, 56-58.5 mm. They are however clearly larger than the bright orange typical P. vetusta that I was able to collect, which ranged from 51-54mm. I plotted the sizes in a graph replicated below.

Chart 1. Four definite P. vetusta from Xuan Son and two definite P. robusta from Mau Son are plotted by size (abdomen incl appendages versus hind wing length). Red crosses refer to two pruinose specimens, both from Xuan Son. The largest appears by colour to be P. robusta, the other could be either. Green squares refer to one teneral specimen from Tam Dao, possibly P. robusta, and one to Philoganga species incertae, see main text. Thus although non-pruinose whitish specimens appear to be constantly larger than orange specimens (but beware of sample size) there is a small area of overlap.

It thus seems that the hypothesis that P. robusta can be identified by colour alone from P. vetusta is supported by the measurements of the specimens involved. Nevertheless more specimens are needed and from different areas to substantiate this. After all, local populations may be genetically homogeneous, which may influence the size distribution.

In the graph a single Philoganga species incertae is represented by one of the green squares. This specimen was caught in Cao Bang Province close to Cao Bang city on May 20. From its size it seemed to fit P. vetusta. However, the dorsum of S1-4 is black, not even whitish. It has a cream bar over the cranium of the head, which is absent in either P. vetusta and P. robusta when mature, although this may be an indication that the present specimen is still immature. In fact at first I dismissed it as just that, an immature P. vetusta. However, as can be seen from the pictures below, it has two strange characteristics in its wing I have not seen in any other Philoganga. The most striking is that vein 1A seems to run on further than in other species, where it curves back to the wing margin. Therefore even at the wing margin there is only one row of cells between 1A and CuP, whereas in P. robusta and P. vetusta there is a whole field of easily 10 cells. Furthermore the quadrangle is much more square than the elongated quadrangles of either P. robusta and P. vetusta. These aspects indicate the possibility of this being in fact an unknown species of Philoganga.

Two males Philoganga robusta from Mau Son and what is presumably a female of the same species. Note the blueish-green colour of S1-4, although the smallest specimen also has a hint of orange.
The same three specimens in lateral view. They are not pruinose, but the males lack orange on the thorax or first abdominal segments.
Three typical P. vetusta males from Xuan Son, displaying bright orange abdomen and varying degrees of clarity of the antehumeral stripe. The top right specimen is similar in size, but has pruinosity covering the first few abdominal segments and sides of thorax. It is difficult to say whether this is vetusta or a small robusta.
Typical P. vetusta male caught in tandem with female. Pattern of dorsum of S9 of female is different from possible female P. robusta. However, this female is the larger of the two, 72mm total body length against 67mm for the Mau Son female.
The same specimens in lateral view, the male displaying bright orange both on the thorax and on the first abdominal segments.
Aged specimens from Xuan Son. Top male P. vetusta showing that aged individuals at least not always covered in pruinosity. Below very large aged specimen with pruinosity on the thorax, but very dull abdomen, tentatively identified as P. robusta on combination of size and lack of bright orange.

Philoganga species incertae. Note the wing pattern with absence of a field between 1A and CuP,  which is very different from the wing pattern of specimens illustrated above. Note also bar over cranium.

Hind wing detail of Philoganga vetusta, showing 10 cells between location where 1A reaches the wing margin and location where CuP reaches wing margin and field at widest location 3 cells wide. 
Hind wing detail of Philoganga species incertae, displaying three cells only between 1A and CuP, and field, if you can call it that, 1 cell wide. Apologies for the legend (A1 versus 1A)

Tuesday, 14 July 2015

Two additional Leptogomphus species

On May 16 I caught a female Leptogomphus in the Tu Le area in Yen Bai Province. On close inspection of the occipital ridge it revealed to smaller lateral horns, protruding backwards, and two central horns bend forward. I was a little baffled and consulted Haruki Karube, who was quick to point out that this was indeed Leptogomphus uenoi, described by Asahina in 1996 and of which the IUCN website says there is doubt it is a valid species, as it was based on a single female. Karube has put that straight, by describing both the male and female this year. The male looks surprisingly like L. perforatus, so it is easy to overlook it, even in the hand. But the female is, at least in hand, distinctive enough. I was happy to find it, of course. It may be widespread, as is indicated by the original specimen being from Sa Pa, the specimens of Karube being from Bach Ma National Park, and my own being from Yen Bai.

On June 17 I caught another female for close inspection on Pia Oac Mountain in Cao Bang Province. This female has two very prominent central horns on the occipital ridge that are both pointing forward and have very thick bases, that touch one another. It misses the backward pointing lateral spikes. I have not been able to match this female with any known species. It may well belong to an as yet undescribed species. Anybody any ideas?

Leptogomphus uenoi, female. Yes, it is a Leptogomphus and yes, other than that it is difficult to tell what species unless you check the occipital ridge.
But if we do so, we see this. 4 horns, to pointing towards the back and to pointed forward in true bull fashion, typical of L. uenoi.
Here at another angle, showing the bull horns
So what it this? It looks exactly the same as the L. uenoi female, although in fact the larger horns are already visible here in lateral view. It is Leptogomphus species incertae.
This is what they look like in frontal view: two thick-set adjoining horns
And here at a different angle you can again see their thick shape, not spike-like, as in many other species, but a water-drop shape. Leptogomphus species incertae.

Monday, 13 July 2015

An additional Coeliccia species from Sa Pa

I am running very much behind with my discoveries of this spring. On May 18 I was checking some small streams in the Love Waterfall area above Sa Pa and one of the species I hoped for was Coeliccia hoanglienensis, described in 2007 by Cuong from the same area. For Vietnam this is still the only location and I do not think it had been recorded after Cuong's record of 2005 of 2 males. But then again, who is looking. By now it has also been recorded from Lao DPR by Yokoi, so it may be more widespread, if thin on the ground. It is a lovely species. I saw just one male over a tiny stream, where it was perched on some grasses.

Another interesting Coeliccia that we now know to be more widespread is Coeliccia mingxiensis. I already mentioned seeing it in Xuan Son in April, but early May I also encountered several males and females on mount Mau Son in Lang Son Province. This too is clearly more widespread, but it also seems to fly only in spring.

With C. hoanglienensis I know have 14 species of Coeliccia in Vietnam. There are several known that I have not seen, like C. doisuthepensis and C. yamasakii, just to indicate the wonderful variety of this genus.

The dark male of Coeliccia hoanglienensis, with blue flanks and mint-green dorsal stripes. Note that it does not have a tail-light.

Close-up of the dorsal pattern of the thorax

The female of Coeliccia mingxiensis at Mau Son mountain on May 3. Note the grey-and-brown eyes and the distinct bands on the last segments.

The male at the same location

Sunday, 12 July 2015

Mature Rhinocypha chaoi and a female Macromia septima

July 12 I went to Mau Son in Lang Son Province, another long drive. And at Mau Son followed the grueling walk down to the stream in the valley, followed by the climb back up. It was warm and it was not pleasant. I also received several bee stings (thank you, bees).

But I found what I came for, Rhinocypha chaoi. One of the prettiest damsels I have seen (and I have seen many). In May I had an immature male, but really wanted to see the adult. In the end I saw 5 males and a female.

While searching for them I noticed a smallish Macromia that flew a few round over the stream and then went up into a tree, where it hung from a leaf. I could just catch it and I was thrilled to see it was M. urania. But then I noticed the face was reddish, and thus it was M. septima! Only the second time I see this species and the second female. The males must be out there!

Male Rhinocypha chaoi. This species is so beautiful, it is unreal.

In dorsal view the abdomen is particularly striking. When it flies about you see azure specks dance over the water surface.
The female up in a tree having a snack.
Female Macromia septima. Note the amber wing-patches and the antehumeral surrounded by red (see also below) 
Note the reddish lower half of the dorsal side of the thorax and the reddish face

Oviposting Bayadera species!

Saturday July 11 I was checking a stream near Nam Bung in Yen Bai Province. Yes, we know that now from the previous posts. But here I want to relate a special spectacle. In the morning I saw a great many Bayadera. Previously I had seen 3 species along this stream: B. hatvan, B. serrata, and B. hyalina. Of these B. hatvan was by far the commonest. This time I did not see B. serrata, but I saw many copula of the other two species. They could be seen ovipositing here and there in floating logs. But in the canyon there was a large tree that had been cut and toppled down into the stream, where it remained standing up. However, it stood in the middle of a water spray from a waterfall, making it soaking wet. There were a great many (several score) tandems ovipositing on it. Interestingly, the tandems formed single species clusters for some reason undoubtedly instinctively clear to them, but not to me.
Three tandems of Bayadera hatvan out of a great many more. It was not easy keeping my camera sort of dry.

A single tandem of B. hatvan. I lined the camera up with the trunk, but in reality they were almost vertical.

Two tandems of B. hyalina, braving the wetness. They were 20cm lower than the Bayadera hatvan tandems.

Adjusted angle of the same tandems of Bayadera hyalina.

Two interesting female gomphids from the Nam Bung area.

Saturday July 11 I caught a small female gomphid near Nam Bung. I had never seen it before and studying it in hand revealed a very neat "horn" on the occipital ridge. Now, female gomphids very often have horns on their heads, but the shape of this one, like the tail of a diving whale ("fluking") is extra-ordinary. This pointed me to the genus Sinogomphus. This is, at least for me, really exciting. Last year in early May I had caught Sinogomphus leptocercus in the same general area, but thereafter the species remained elusive, in spite of several searches. I have no description of the female of this species, so I have to exercise some caution here. Nevertheless it is not very likely at all that there is another Sinogomphus species in the area (there are no Sinogomphus species known from Vietnam). So this should be the female of S. leptocercus!

Another female I caught is Leptogomphus divaricatus. This is not at all a rare species, being probably the commonest species in the north of the genus after L. perforatus. But I have not often seen the female and failed so far to take pictures of its distinctive divaricate horns. Glad to put that right!

First the female of Leptogomphus divaricatus, typical as Leptogomphids go.

But they can often be told apart by the horns on the occipital ridge. L. divaricatus has two that bend outward in opposite directions.

But look at this! Is this remarkable or what? Female Sinogomphus leptocercus. As if mommy bound her baby's hair together into a little palm tree.

Dorsal pattern fits several Sinogomphus species and of course also S. leptocercus.

The whole specimen in lateral view. The lateral pattern of the thorax is a little different from the male (see that entry), but otherwise patterning is similar.

Trip to Nam Bung (Yen Bai) - a superb surprise and a second Anotogaster*

*Adjusted on June 1, 2016. This subspecies now published as Orthetrum melania superbum.

July 11 I drove all the way to Nam Bung along the QL32 (in Yen Bai Province) in search of an enigma large Periaeschna species, of which I caught a female two weeks back. But I failed to see it again. I spent the beautiful day along a stream that runs through forest and a canyon, the same place where I had seen the Periaeschna.

The trail through the forest had some puddles and it was here that I spotted a large pale-blue Orthetrum with pale appendages, a dark face, and a black dorsum to the thorax with very prominent and clear antehumeral stripes. The wingtips had a darker crescent and the wing bases had a prominent blue-and-black basal patch. I was pretty convinced that by now the genus Orthetrum was not going to present surprises, but here I was faced with what was obvious a new species for Vietnam.

I collected a single male of the 4 males present at the puddles. It is very weird. These puddles were dirty, with buffalo crap and mud, nothing special. If you consider this, why on earth would this species be rare? Also interesting, Orthetrum triangulare was omnipresent (it is a very common species in this area), and also all around, but not at these few puddles. Clearly it can not compete with this species (in fact the abdomen of O. triangulare is 30mm, but of the present species 37mm, so it is much larger).

From the shape of the appendages, the coloration (face, wing base and tip, abdomen, thorax (but not the dorsum) I can only conclude this is Orthetrum melania. This species was long considered to be a subspecies of O. triangulare, although that is no longer the case and the co-exist in the south of China. Indeed, structurally the caudal appendages and sex apparatus look similar unless you look carefully. Originally this species was thought to be restricted to Japan, but it is now known to have a much larger range. O. melania has also been found in Guangdong, Guangxi and Yunnan. Therefore it is maybe not surprising it also occurs in Vietnam.

There are however a few aspects that indicate that this may be an (unknown) subspecies. The specimen is right at the top of the range for Japanese specimens, with abdomen 37mm. The median space in the hindwing is clear, but integral part of the basal patch in the Japanese specimens. The basal patch is also smaller, not covering the base of the anal loop. But most prominently, the dorsum of the thorax has no pruinosity. It is solid black with clearly demarcated antehumeral stripes that are not pruinose, but truly blue in color. These antehumerals are surprising, because they are absent in the true O. melania, which has a unicolored pale dorsum as immature, that gets covered in pruinosity like the rest of the thorax. Most Japanese specimens have all black appendages, but some have paler tips of varying extent. As can be seen in the photos of the Yen Bai specimens there is some variety there too, from all pale to pale in the apical halve. Nevertheless, the overlap in characteristics makes it unlikely this is a completely different species. I am curious to hear what specimens in the south of China look like. If they are the same as in Japan the present specimens are even more remarkable. I have not been able to find any similar species on the web.

Another surprise was Anotogaster klossi. I have seen A. gigantica in the same general area, but A. klossi only at Pia Oac. Interestingly, it passed over the same track and puddles where I found O. melania.

Let's get this out of the way. Anotogaster klossi, with characteristic reddish colour on abdomen, yellow mandible bases and long superior appendages in which no obvious tooth visible halfway. 

To start the argument: scan of Orthetrum triangulare (top) and O. melania (bottom). The size difference is obvious.
The first male O. melania I noticed. This specimen has completely pale appendages.
The same male in dorsal view. 

The same male in hand. The dark face clearly visible. But what is especially eye-catching is the dorsal pattern. Although the lateral grey is a powdery substance that is easily scratched, the antehumeral stripes (or maybe dorsal stripes is better) are not the result of powder. They contrast very strongly with the solid black remainder.

Note the lack of colour in the median space

Another male, with mostly black appendages with only pale apices.

Appendages in ventral view
In dorsal view
And in lateral view
The hamulus and lamina in lateral view