Tuesday, 25 August 2015

Periaeschna sp. (species novum?)

The Yen Bai area is a true treasure trove for Aeshnids in early summer. Several species of Planaeschna, of Periaeschna, of Petaliaeschna, of Cephalaeschna. Karuki Karube had alerted me to the occurrence of a large Periaeschna of which he had only seen teneral specimens. Well, June 30 was a very hot day and around midday quite a few Aeshnids were hanging in cool shaded places along one of my favorite streams. One specimen was flying around a bit between a few large boulders and I was ale to catch it. It appeared to be a Periaeschna, but it just seemed very bulky. Later at home the difference between this specimen and normal P. magdalena was striking. Even if I have not been able to catch a male yet, this must be the enigma large Periaeschna sp.  and a possible species novum. At 76mm this is a large insect!

This insect is almost identical to P. magdalena, but for its much larger size

And, as is visible here in lateral view, the yellow markings on the abdomen are much more prominent

Sunday, 23 August 2015

Somatochlora dido - another Sa Pa goodie

This weekend we went to Sa Pa to search specifically for a quite brilliant and seldom seen emerald, Somatochlora dido. This is an autumn species, seemingly flying from August to October. Sebastien Delonglee has some stunning photos of the species on his blog and clearly I wanted to see this species for myself. So we drove to the Love Waterfall area and arrived at 10.30 in the morning to see several males almost immediately. Just as well, for clouds started to build up before I got a few shots in and after that we had to wait quite a long time for a few short spells of sunshine, during which one male reappeared. I was able to make some quick in-flight shots before it took off again and it became cloudy once more. Hopefully I will have another and better opportunity later this autumn, but for now I am just happy that we saw it.

The species was described by Needham in 1930 from Sichuan. It has been recorded from a few scattered high-mountain locations in southern China. Wilson synonymised S. dido with S. taiwana from Taiwan, after finding that specimens from Guangxi were intermediate in the structure of the appendages. It is interesting to note that specimens from Taiwan seem to miss to first lateral stripe, which is so prominent in S. dido. Be that as it may, S. dido was recorded in 1995 by Asahina from the same general location as where Sebastien found it again in 2012 and 2013. To this we can now add my own 2015 records. So far the only site known from Vietnam, although it may be occurring in the forest around Fansipan. There are various bogs in there, although difficult to access because entry is restricted.

Somatochlora dido, male. Note the diffuse orange-yellow postclypeus and bright yellow labium, and the two yellow lateral stripes.

This species hovers about 1-1.50 m high over trickles in acidic swamp areas and flies amongst tree tops when hunting

Tuesday, 18 August 2015

Anotogaster klossi - the redder the better?

Although the IUCN site, based on 2010 knowledge, classified Anotogaster klossi as DD (data deficient), Karube in 2012 in his overview of Vietnamese Anotogaster species described and illustrated the male, thus filling a gap in our knowledge. The species had already been published for Pia Oac by Asahina in 1998 and Karube mentions specimens from Pia Oac from 1996 and 1997. Moreover, he published a specimen from Bach Ma in Central Vietnam. In a recent post I published a male from Yen Bai Province, but I have seen this species regularly at Pia Oac between late May and late August, with a maximum of 10 on June 17. And although I had seen males until that day, it was on June 17 that I saw quite a few females, which served to support the initial identification of the males. The female is remarkable, not just because it is one of the largest dragonflies I have seen (about 11.5 cm including the ovipositor), but also because she is unique amongst Anotogaster species in having a largely orange abdomen, which is very striking both in flight and perched.

This is her, the orange monster! So big that I had to stretch uncomfortably to be able to take her picture in hand. 11.6 cm, this beauty.

Posed, but still pretty pleasing
The same female as in the previous two pictures

This male however properly perched, not posed. Note the characteristic orange areas on the ventral side of the abdomen, merging with the yellow rings, and the yellow base to the mandible

Sunday, 16 August 2015

Nepogomphus walli - again

Last year I was bumped into several freshly emerged Nepogomphus walli specimens when checking the slopes on the south side of Pia Oac mountain on 23 June and again on 8 July. I was happy that this year I found an immature male to the northwest of the mountain, but also in Cao Bang Province, about 60km from the previous location, on June 18.

Nepogomphus walli, immature male, showing the typical white superior appendages with swollen base and black tips.

Nychogomphus flavicaudus - New for Vietnam

It always pays to wade into rivers towards dusk and look for gomphids in spring and early summer. There are many species that only appear close to dusk and either patrol or hover over the water. On June 17 I therefore waded into a river close to Cao Bang City and noticed several medium-sized gomphids hovering over the water. But the current was strong, so it took quite a while before I finally was able to net first one and then a second. In hand it was immediately obvious this was an exciting species, because of the shape and colour of the appendages.

Basically it was very similar to a species I had seen earlier at Cat Tien National Park, Nychogomphus duaricus. Although that is much further south, this species has also been recorded from Yunnan in China. But checking Chao it dawned on me that this was in fact Nychogomphus flavicaudus, a species thought to be endemic to Hainan.

Having said that, these species are extremely similar, so I will not be surprised if DNA-analysis would indicate they are in fact the same species, or subspecies. The most noticeable differences are 1) the antehumeral pattern (a humeral spot and a separated humeral line or series of small spots forming a broken humeral line in N. duaricus and only an antehumeral spot in N. flavicaudus) and the size (abdomen around 36mm and hindwing around 27mm in N. duaricus, abdomen around 40mm (total body length 54mm) and hindwing 33mm in N. flavicaudus). It must be noted that Asahina (1986) points out that specimens of N. duaricus from Malaysia also miss the antehumeral line. But if we follow current practice, then the specimens from Cao Bang must be considered N. flavicaudus.

This brings the number of Nychogomphus species in Vietnam to three. The other is N. lui (see Sebastien's site. I have not been lucky enough to bump into this species that inhabits large rivers and occurs in the suburbs of Hanoi).

Top 2 specimens are N. flavicaudus from Cao Bang. Bottom specimen is much smaller N. duaricus from Cat Tien. Shape of appendages is virtually the same between the two species. Tips of superiors are somewhat more flattened in N. flavicaudus specimens, but not to the same degree in both, so the consistency of this trait is questionable.
Male Nychogomphus flavicaudus. Note the antehumeral spot, but complete lack of antehumeral stripe.
Appendages in dorsal view
Appendages in lateral view
Facial pattern similar to N. duaricus, but extent of yellow patches somewhat reduced

Wednesday, 12 August 2015

Bayadera melanopteryx and female Bayadera serrata

On May 25 I bumped into Bayadera melanopteryx for the first time. This is quite an easy species to recognize, courtesy of its darkened wingtips. It is a species that is widely distributed in the southern half of China and known to extend into the north of Vietnam, for instance around Pia Oac in Cao Bang Province and also around Sa Pa. My first encounter was near Sa Pa, but I also saw it several times around Pia Oac. The latest date was June 28.

There are distinct populations of the species in China with consistent differences in the extent of the darkened areas in the wing, so it is possible this is a superspecies, but until that is proved it is best to treat all populations as B. melanopteryx. The Vietnamese specimens all have the apical half of the outer wing blackish.

I know have also found B. serrata in quite a few additional locations to the spot north of Pia Oac where I first saw it last year. Apart from several sites around Pia Oac, it was also rather common close to Tu Le in Yen Bai Province and to my surprise I also ran into a female in Xuan Son National Park. Another addition to the already extensive list of that place. Earliest record this year was May 23 and latest was June 30. Apparently not so rare as thought.

The very dark body of the male of Bayadera melanopteryx

Which becomes very easy to recognize once you see the wingtips. Bayadera hatvan has clearly darkened wingtips and Bayadera hyalina has slightly darkened tips, but never as extensive and clear-cut as in B. melanopteryx
The female of B. melanopteryx has similarly darkened wingtips, although not as dark brown as in the male. The thorax pattern recalls B. hyalina, but see the completely pale metepimeron.

In dorsal view the curved dorsal stripes are also very different

Here is the first of two photographed females of B. serrata. In patterning of the thorax very similar to the male. This one is from Pia Oac.
Whereas this one is the female from Xuan Son, found inside the forest not far from the main stream.

Sunday, 9 August 2015

Camacinia gigantea - finally!

Sebastien recorded Camacinia gigantea in a park in Hanoi in mid-April several years back, proving that the species occurs at least as a vagrant in northern Vietnam. It has also been recorded from the south, for instance from Cat Tien by Cuong. As this is one of the largest libellulids in the world and good looking too, I was eager to see it and kept my eyes open for it over 2 long years. When I could not find it in the north, I assumed it would be easier in the south, but during my visits to Cat Tien I could not find it there either. And likewise I never saw it in the Mekong Delta, although it reputedly occurs close to the sea and in mangrove areas. Clearly it is not common in Vietnam and at least in the north must be rare. It is after all a rather large and conspicuous species.

Today I visited Xuan Son National Park with the objective of finding Planaeschna species. Maybe as the result of the three weeks of cold and rain there were not that many dragonflies around and several species normally common were completely absent. But when I checked the little round shallow pond area that generally produces Orolestes selysi and Gynacantha species I got a thrill when I noticed two large red dragonflies fluttering over the now brim full pond. Two males of Camacinia gigantea! Somehow floating in the air at high altitude they must have noticed the shallow vegetated pond where for sure they normally do not occur. One male disappeared, but the other perched on twigs and emergents all day. That is, when it was not patrolling the pond in large circles, with bouts of rapid wing beats interspersed with short gliding moments. Its flight pattern not so different from that of Camacinia harterti, although that species stays inside the forest.

This species was a dream come true for me. There are several species that Sebastien recorded and that I have not seen yet, but this one especially has been bothering me.

First shot of the two males flying together. Actually they did not really seem to chase each other. In fact they seemed to ignore each other most of the time, even when both were patrolling

This one male Camacinia gigantea perched in the afternoon in the shade on emergent vegetation. Few leaves could support its weight when it grasped them, so it had a few preferred spots.
It is a magnificent species. The large hole in the right hind wing indicates it has travelled (I presume) 

The venation is magnificent. I did not try to count the number of cells in the anal loop, but there are many. The detail is mind-boggling.

Planaeschna cucphuongensis - luckily more widespread?

In 1998 Haruki Karube collected a male Planaeschna on June 2 from Cuc Phuong National Park, which he described in 1999 as Planaeschna cucphuongensis. The species appears rare at Cuc Phuong, but was also found by Ellenrieder et al. Yokoii has also recorded it in Lao, so it may be more widespread. Nevertheless, I was surprised to find it on May 11 in Pu Luong Nature Reserve, which is quite a bit higher in altitude than Cuc Phuong, although belonging to the same mountain range. Pu Luong lies west of Cuc Phuong. The location I found the species was about 60km west of central Cuc Phuong. First I caught a female and subsequently a teneral male. This male fit the description by Karube very well, albeit that it was very fresh. The female was mature, but a proper description of the female is lacking. I therefore wanted to verify the identity of these two specimens against specimens from Cuc Phuong. I had not been successful in locating the species in Cuc Phuong before, but on June 16 I went to the general location where it had been recorded by Ellenrieder et al. and I was lucky enough to find a female. This female is identical to the female from Pu Luong, supporting the identification of the teneral male. In view of the scarcity of the species at Cuc Phuong, this is a great to know. In stead of being a rare species restricted to the National Park, it ranges possibly wide both over an altitudinal range, as geographically all the way into Lao DPR.
The species is one of several (like P. guentherpetersi, P. tomokunii, and P. species novum from Xuan Son) that have a generally brown-orange face. It has limited dorsal markings on the abdomen. The female has the ventral half of S2 all yellow, and has extensive brown basal patches to both fore and hindwing.
Female Planaeschna cucphuongensis. Note extensive dark basal patches, large yellow ventral areas to S1-2 and base of S3. Also S4-7 with only mid-dorsal spots on the dorsum and none on S8-10, mirroring the pattern of the male.

Scan of dorsal view. Note lack of cross-veins in median space, indicating Planaeschna.

Face of the female from Cuc Phuong. Sort of uniform orange, although frons darker, especially towards dorsal side and labrum more yellow
The face of the Pu Luong female, too dark a photo, but even so it is obvious the pattern and colour are similar

The Pu Luong female, showing same characteristics as the female from Cuc Phuong, just somewhat fresher, as she is younger
Teneral male Planaeschna cucphuongensis. Photos taken in local hotel in the evening after allowing the specimen to dry. Sadly it could not take shape properly. Nevertheless patterning of abdomen, even if vague, can be seen. Mid-dorsal marks are the only markings on the dorsum of S4-7
Typical appendages in dorsal view, nicely rounded on inner edge in apical half. Identical to holotype description.

The face of the teneral male, indicating it will likely be darker on the frons (and postclypeus) when mature.

Ventral view against hotel bedding. Median space without cross-veins indicating Planaeschna. Anal loop 6-celled and triangle 3-4 celled in fore and hindwing (description of holotype 4-5 celled)

Tuesday, 4 August 2015

Another Devadatta - and easy to boot

9 and 10 May, it seems ages ago, I visited Ha Tinh Province with Toan, close to the border with Lao PDR. On both days I saw at a small trickle under dense forest cover a species I had hoped to find for a while now: Devadatta cyanocephala. Unlike the Devadatta ducatrix / kompieri doublet of the previous posting, this is a distinctive species. Not only has the male markings on the thorax, both male and female have the bluest faces imaginable.

Devadatta cyanocephala is known from Lao and several provinces in Vietnam, including Ha Tinh. As far as I know this is the furthest north is has been recorded until now. When I revisited the place in June I could not find any, so possibly  it is a spring species.

Male Devadatta cyanocephala. Like congeners darkened wingtips. But it has pale lines on the thorax over the sutures.

Under this angle the distinctive blue face becomes apparent

And right from the front it can no longer be ignored: this is a blue face. It makes it easy to separate this species from its cousins. Imaging being a small bug and being devoured by something so blue! What a way to go.
Here is a not so good shot in hand of the female. Note the broad stripe over the flank.

Her face is still blue, but not as blue blue as that of the male

Saturday, 1 August 2015

Devadatta ducatrix and D. kompieri - an appraisal

Until this year, the identification of Devadatta specimens in Vietnam seemed straightforward. There was one rather dull looking species called D. ducatrix and there was a slightly less dull species with a blue face called aptly D. cyanocephala. And because the situation was simple, I did not collect specimens of the dull species, which is a regular occurrence in hill and mountain forest in the north of Vietnam, where it inhabits shaded trickles.

This situation changed drastically after I last year explained the productive Yen Bai site to Toan and he visited it in the middle of May. He collected several Devadatta specimens and concluded that some represented an as yet undescribed taxon. This spring the new species was published in Zootaxa by Phan, Sasamoto and Hayashi. They did me the honor of naming the new species after me.

The differences between D. ducatrix and D. kompieri are slight and based on a comparison of very few specimens. But at the same time the complete set of differences should enable identification, although the authors stress that it is important to collaborate their findings with DNA analysis in the future, when the extent of the populations is more clear and more specimens are available.

Obviously I was keen to see this species carrying my name for myself and in the middle of May headed to Yen Bai Province. This year, I had decided, I would collect Devadatta specimens to compare. The first time I ran into the species was on May 14 still east of Nghia Lo on a mountain pass and almost 80km from Tu Le, where the species had been found by Toan. Later that day I also had them in that area. What is more, over the spring and early summer I noted the species regularly in Yen Bai, but also caught a male of what I concluded was D. kompieri near Lao Cai along the lower part of the road up to Sa Pa. In fact, I found few specimens of D. ducatrix this year, for instance in Thanh Hoa, Lang Son and Cao Bang Provinces.

I used a combination of characters from Phan et al. to identify the specimens, but also noted that some were not consistent. I caught for instance a specimen in which the number of cells between the first anal vein and the trailing edge of the hindwing (should be 2 in D. kompieri and 3 or more in D. ducatrix) was 2 in one wing and 4 in the other. Sadly it afterwards escaped when I tried to administer some moisture to it to keep it alive.

Today is a very rainy day in Vietnam and anyway, the season for Devadatta is over, so today I had a closer look at all specimens collected this season. I have 9 usable D. kompieri males, 1 D. ducatrix male and one female of both species (presumably), plus a scan of two presumed D. ducatrix males from Cao Bang.

Let's first summarize the differences described by Phan et al. for the two species. I paraphrase from the article, but slightly adjusted to exclude the references to D. yokoii.

(1) D. kompieri is smaller (Hw 31–34; abdomen including appendages 32–37) than the more robust D. ducatrix (Hw 33; abdomen including appendages 39 mm in our specimen, and each 40 and 43.3 mm in holotype (Lieftinck 1969)). (2) Wings of D. kompieri, compared with those of D. ducatrix, are proportionally shorter and have a less rounded apex and a narrower dark marking at tip. (3) The pterostigma is proportionally longer and narrower in D. kompieri than in D. ducatrix. (4) The venation of D. kompieri is less dense, especially in the space between first anal vein and posterior wing margin in the Hw, which consists of two cell rows at most, whereas there are two to three rows in D. ducatrix. (5) Superior appendages of D. kompieri are slimmer, while those of D. ducatrix are broader). 

The authors compared 4 specimens of the new D. kompieri with a single male D. devadatta also caught at Tu Le. Based on the extent of the dark marking at the tip of the wings and the shape of the pterostigma all my specimens from Yen Bai and the specimen from Lao Cai seem to be D. kompieri, whereas the one male from Thanh Hoa should on the basis of these characters be D. ducatrix, as should the two males I scanned from Cao Bang. If we look closer at the 9 D. kompieri specimens, length of abdomen (incl appendages) ranges from 36 to 41.5 mm (this is the specimen from Lao Cai, largest for Yen Bai is 41mm (2 specimens). This overlaps with both the one specimen identified by Phan as D. ducatrix and the size of one of the types from Lieftinck. My own D. ducatrix specimen has 38mm. Therefore it is questionable whether the size criterion is useful.

Hindwing length in my specimens ranged 32-38mm, again including the measurements of Phan's D. ducatrix specimen and also that of my own (34mm). This is logical, larger specimens will have larger wings generally. It illustrates that these measurements are of limited value to separate the species.

Relative hindwing length compared to abdomen length ranges 0.86 - 0.93 in D. kompieri (N=9) and 0.89 - 0.96 in D. devadatta (N=3). Although sample size is very limited, this may indicate that on average D. devadatta has slightly longer wings relatively. Nevertheless, given the overlap and small sample size, it remains to be seen whether in certain cases this may be of value.

In the pterostigma of the D. kompieri specimens (in 8 out of 9) the length of the pterostigma that is confluent with the costa is less than half that of the total length. In the D. ducatrix specimens it is slightly more than half. And the number of cells completely covered by the pterostigma is 4 in D. kompieri (one specimen 5), whereas in D. ducatrix it is 5 (one specimen 4). Therefore the shape and size of the pterostigmata in combination with the denser venation of D. ducatrix may be an indicator of specific identity.

However, the number of cell town between the first anal vein and the trailing edge of the hindwing appears to be of limited value and even varies within specimens between left and right. Sample size is limited, but number of cell rows (the maximum in the field) ranges 2-3 in D. kompieri (with only 2 specimens with maximum of 2 in both wings) and 3-4 in D. ducatrix (but one specimen with only 2 in one wing).

Last, I postulate that there is no consistent difference in the width of the apical part of the the superior appendages, whereas the inferiors are rather variable in outline in dorsal view. I consider the appendages of no value to support identification, but it must be stressed this is based on a single male D. ducatrix being no different from 9 males of D. kompieri.

In addition, although not given as an ID characteristic, the slightly amber colour of the wings in D. kompieri when mature also occurs in D. ducatrix when mature.

To summarize for the male specimens, apart from the size and shape of the apical spot on the wings, there is little to consistently support that this is a valid indicator of specific identity. Size is of no value, and shape and relative length of the wings either extremely limited or also of no value. It does seem that the density of wing venation may have some very limited usefulness, although D. ducatrix with only 2 cells between anal vein and trailing edge are to be expected, given that one of the 3 specimens examined has only 2 cells in one wing. The sample of D. kompieri does not contain any specimen with an abundance of 3 row cells or with 4 rows (although escaped presumed D. kompieri specimen had one wing with 4). In addition, the shape of the pterostigma also appears almost consistently to be different. Shape of the appendages appears not to be of value for identification.

When comparing the single females of both species (identified on the basis of extent of apical spot and association with males, although not in tandem) reveals that abdomen length of D. kompieri is 35.5mm compared to 32 for D. ducatrix. Hindwing is 34 in D. kompieri and 32.5 in D. ducatrix, thus supporting the conclusion that D. ducatrix is not consistently more robust than D. kompieri. Both specimens have 2 cells maximum between the first anal vein and the trailing edge, but D. kompieri has only 3 cells covered by the pterostigma against 4 in D. ducatrix, which is in line with the males. Whether this is consistent remains to be seen, given that the comparison is based on single females.

However, the cerci of the female D. kompieri are much shorter and more like an equilateral triangle than that of D. ducatrix. In D. kompieri to ovipositor extends beyond the tip of the cerci, in D. ducatrix this is reversed.

So, not all hope is lost. It is possible that D. kompieri and D. ducatrix are different, but clearly they are very similar species or subspecies. Differences in wing venation especially are of limited value when so slight as is the case here. Most differences appear clinal. Whether the differences are the product of peculiarities in geographical populations or truly represent separate species may require more research and, as the authors rightfully suggest, collaboration by DNA analysis. If it can be shown that the structural differences between the females hold up in larger samples this will support the case for two different species. 

Devadatta kompieri male from Lao Cai. The largest specimen and somewhat in between the two species as far as the shape of the apical spot in the fore wing goes. Number of cell rows and shape of pterostigma consistent with D. kompieri.
Same specimen from Lao Cai in lateral view
Male Devadatta kompieri from Yen Bai. Long pterostigma with few covered cells, two rows of cells in hindwing between first anal vein and trailing edge, limited apical spots.

Same male in lateral view

Rather typical Devadatta ducatrix male from Thanh Hoa. Note extensive apical spots, particularly in hindwing, more square pterostigma with 5 covered cells and 3-4 cell rows in hind wing between anal vein and trailing edge
Same male in lateral view

Two female Devadatta. Presumed D. ducatrix top and presumed D. kompieri bottom. Pointed face of latter due to opened mouth.
S8-10 of presumed female D. ducatrix. Note slender and long cerci
S8-10 of presumed female D. kompieri. Note shorter and stubby cerci.

Finally, two males of D. ducatrix from Cao Bang. Bottom male with limited extent of apical spots possibly result of very immature state, but specific identity not entirely sure (if we assume there are indeed two valid species). What is of interest here is that this specimen has 2 cell rows between first anal vein and trailing edge in right hindwing, but 3 in the left. In escaped presumed D. kompieri even more extreme difference observed of 2 in one wing and 4 in other.