Tuesday, 19 June 2018

Burmagomphus magnus - expected in Vietnam

On June 4 Odonatours visited the area of Cao Bang during its tour of northern Vietnam. On this day James Holden joined us from his 'home' in Cat Tien. Together we checked a large stream not far away from the town. While we were pre-occupied with other Odes, James took a photo of what appeared to be an unknown Burmagomphus. Burmagomphus vermicularis and B. divaricatus both occur in the area, but this was clearly different. After a visit to Pia Oac on the 5th, we went back to the stream on the 6th and were lucky enough to relocate this wonderful gomphid. Upon capture the details of the appendages could be verified and the initial suspicion this might be B. intinctus seemed confirmed.
Burmagomphus intinctus is only known from several specimens collected from Fujian in China, which is truly not exactly around the corner. And indeed, further perusal of literature (thank you, James) showed it to be B. magnus, described in 2015 from Hekou district in Yunnan Province in China, which is just over the border from northern Vietnam. It was therefore to be expected.

The original photo by James Holden. What is that?!
Two days later, probably the same individual in hand.

The strong hook on the posterior hamule

And the rounded epiproct and somewhat sinuous superior appendages

Wednesday, 15 November 2017

Gomphidictinus tongi, a wonderful discovery from Vietnam

In May 2016 I observed, but could not catch, a large Gomphidia-like gomphid in pristine forest just south of Phong Nha - Ke Bang National Park in Quang Binh Province in Central Vietnam. I thought it might have been Gomphidictinus kompieri, because of its deep forest habitat. I visited several times later in the season, but it rained every time and so I did not see it again. But this year I visited in early June and was more lucky. Not only did I catch a male, I also found the species next to the botanical garden of the National Park. And it clearly was not G. kompieri. It was a new species for sure, judging from the shape of the appendages, coloration and wing venation.

Not long after I was contacted by Zootaxa regarding a manuscript for a new Gomphidictinus species from China by Haomiao Zhang and colleagues. And what a surprise when this turned out to be exactly the same species: Gomphidictinus tongi Zhang, Guan & Wang, 2017. This lead to an interesting debate regarding its genus. Although the species is currently included in Gomphidictinus, in the same manner as G. kompieri was included in it, on the basis of the spine on the vesica spermalis, differentiating between Gomphidia and Gomphidictinus is not straightforward, not on the basis of this spine, nor on the basis of for instance wing venation. An overhaul of the genera, including DNA-analysis, is needed to solve this, but for now this fabulous dragon is included in Gomphidictinus as the third member of that genus.

Some unidentified Gomphidia / Gomphidictinus reported from Tam Dao by Natalia von Ellenrieder likely also concern this species, which therefore may be more widespread in Vietnam, apart from ranging widely in China (now recorded from Guangxi and Hainan). Interestingly, the two male specimens from Vietnam in below pictures indicate some variability in the maculation of the abdomen.

Female of Gomphidictinus tongi. It has wide flaps to S8, although not so visible here

Typical male showing already striking yellow markings compared to the two other species in the genus.

Slightly overexposed, so not as yellow, second male, but note extensive marking of S6 compared to the first.

Tuesday, 25 July 2017

Saying good-bye, a last visit to Xuan Son National Park

After 4 years of oding in Vietnam, I will be leaving. This blog will continue, because there is still a lot to publish. I have just been too busy trying to clean up some remaining issues. There simply was not enough time to write entries. Articles are the priority and even there I am behind. Not sure how many species the tally is, after 4 years. Probably around 440 species, but many first need a formal description. And then there is so much out there still to discover.

This spring and summer has been awful for dragonflies. It has just been cloudy and rainy. Some of the puzzles I wanted to solve therefore remain unsolved for now. But at least Sunday 23 July was a good and sunny day, even if I got soaked in the morning. The upside: only one leech lodged on my stomach.

Xuan Son has been wonderful, although the forest is being opened up by road building. I hope that will not lead to further incursions. The trees still stand and the stream remain good. Not sure how many species I actually saw there, somewhere in the range of 125-135 species. With several new species described and several more on the way. So, with the promise of some sun, this is where I went for my very last outing.

And to my huge surprise I ran not into 1, not 2, but 3 species I had not recorded there before. The first was a male Orthetrum melania superbum, a subspecies of O. melania described, and also only recorded, from Yen Bai. A large and conspicuous dragonfly that apparently tolerates abysmal conditions (puddles with muddy, water buffalo dung infested, water), but is nevertheless hardly ever seen. A single male attended a small pond. Fantastic.

This remains one of the most beautiful Orthetrum species I have seen 

By the early afternoon I wanted a change of scenery and drove to a nearby hill in the forest and noticed a dragonfly seemingly ovipositing on the wet concrete road. I got out and caught it and was very surprised to see it was a male, so why was it dipping its body in the wetness of the concrete? And it was a Chlorogomphus, in fact it was C. auratus, which I had never recorded in the park before. I guess I focus too much on the one fantastic stream, but ignore trickles on other mountains.

What is splendid discovery, Chlorogomphus auratus

Further afield still I wanted t check the area on the other side of the central hamlet and stopped by a small stream. A tiny trail ran next to it and I went in to see what it had to offer. And bumped into a small, Coeliccia pyriformis-sized, Coeliccia with large pale blue dorsal markings, a little like larger C. uenoi, but more rounded, and much like the even larger species we are currently describing from Ba Be. Indeed, under the microscope it is clearly closely related to that species, with similar genital ligula, similar appendages (although details differ), but obviously different thorax pattern and abdomen pattern (apart from the total insect being smaller than the abdomen of the Ba Be species alone, which is very robust).

To make sure it was not just aberrant I searched high and low and eventually, in a rather different location, was able to locate a second male, which was exactly like the first. How wonderful, to wrap up Vietnam with a new species of Coeliccia (coincidentally the 9th species of the genus occurring in Xuan Son, amazing).

Wonderful Coeliccia spec. nov. 
Close up of the thorax

So, back to the Netherlands and time to write up in earnest!

Wednesday, 21 June 2017

Two new Stylogomphus species for science and for Vietnam

Today my paper on two new Stylogomphus species was published in Tombo. And with it two species I had found last year have received a name. The first I found along the Ho Chi Minh Highway just south of Phong Nha - Ke Bang National Park in May 2016 (and again this year) and also a little north of Khe Sanh. The other, a tiny species, I found perched in bright sunlight on a rock in a stream near Bao Loc in Lam Dong Province. Stylogomphus species are notoriously similar in their outward appearance, but have obviously different caudal appendages. That means that it is virtually impossible to separate them by observation or even photos, much like Leptogomphus species. Here are photos of both species.

Stylogomphus delicatus, a species with long and deeply cleft inferiors

Stylogomphus annamensis, a species with short and rounded inferiors

Saturday, 17 June 2017

Macrogomphus matsukii in Cat Tien

James Holden had been reporting Macrogomphus matsukii from Cat Tien NP for a while and I decided to pay him a visit to get to see it in May. Last year I had seen Macrogomphus hovering over a large river at dusk (a habit shared by many gomphids, and certainly M. guilinensis) in Quang Binh Province, but had failed to ascertain beyond reasonable doubt that it was this species. Photos by James from last year had us initially count whether it was M. borikhanensis or M. matsukii, because the lateral pattern on the thorax had only two clear stripes. Facial pattern is very much like M. matsukii though. There seems to be some doubt whether these two species may in fact be conspecific anyway. Just before I went to Cat Tien the rains picked up and the riverbed filled up quickly, so that circumstances had changes considerably when I got there on May 12. Indeed, we saw none, but on the 13th the waters had receded a little and the circumstances the species seems to favor (small trickles over the rocks by the side of the main stream) were restored. And towards dusk: there they were. 3 males hovering over the streams, for a short period joined by a Orientogomphus naninus. That distracted us and therefore I failed to get the stunning pictures I was hoping for. The different individuals had some variability in the extent of the middle lateral stripe, which was absent or represented by a small mark at the dorsal end. Otherwise they seemed perfect for M. matsukii.
This species was described from Thailand and reported also from Lao (IUCN website) and Cambodia (Kosterin, pers. comm.). Not surprising then it also turns up in Vietnam. Here is the best photo.

Male Macrogomphus matsukii, hovering at dusk over stream

Thursday, 15 June 2017

At long last another Lestes

Considering my world Odonata list, Lestes is one of the genera with the most recorded species and that is not surprising, giving the number of described species and the fact they occur around the globe. But irrespective of that, there are not that many species around in Vietnam, apparently. Only three I had been able to find. Lestes praemorsus is the common species, found from the very north to the very south, and Lestes elatus from the southern half of Vietnam. Lastly, I recorded pretty Lestes nodalis from Huu Lien Nature Reserve, to the north of Hanoi. And that was it. Until on May 12 this year I stopped by the road in Lam Dong province, to the northwest of Bao Loc, to check a grassy inundated area in the afternoon. I noticed many Lestes praemorsus, but it dawned on me that some appeared to be larger than others and these all had a reduced pale abdomen tip. This could not be a coincidence. I took photos and collected a few. In the evening I became disappointed. It seemed the appendages were the same, so maybe just variants? But when I returned home several days later and was able to check them under the microscope, it became clear there were in fact differences. Most striking were the differences between the inferior appendages of the species, in addition to the aforementioned differences in coloration. Two species appeared to have this combination of characters, Lestes dorothea Fraser, 1924 and Lestes praecellens Lieftinck, 1937. The former is quite large, a little larger according to the description than mine, which fit better the species described by Lieftinck from Java in size. However, the female I photographed has much more extensive thoracic markings than that species, in line with what is to be expected of L. dorothea. That species is recorded from India, Thailand and Malaysia. Based on the structural characteristics and patterning of the male and patterning of the female I think it is safe to conclude this is L. dorothea as well.
By the way, based on the likeness of the appendages of L. praecellens and L. dorothea one may ask whether these are truly different species. There thoracic markings are also rather similar, if it weren't for the female.

Lester dorothea male. Note the lack of pruinosity on S9.

Male and female of L. dorothea

The female, showing the extensive dark markings on the thorax, unlike L. praemorsus

Another male showing the limited pruinosity on the abdomen tip

A Lestes praemorsus male for comparison. Smaller and with pruinosity on S9.

Sunday, 23 April 2017

Not a Bao Loc specialty - Heliogomphus chaoi

Karate (2004) described Heliogomphus chaoi from Bao Loc in Lam Dong Province in the south of Vietnam. This species is very similar in appearance to Heliogomphus selysi, a species occurring in for instance Thailand. H. chaoi differs especially in the shape of the vulvar scales of the female and the lack of prominent spines on the occipital ridge. In stead it has two small horns behind the lateral ocelli. Karube also notes that the superior appendages have a venture-lateral projection at the midpoint, to separate the male from H. selysi. Indeed, Asahina did not mention this for H. selysi, but I would love to see the holotype to verify this.

Anyway, last year I found this species to be common near Bao Loc at the type locality in early June. But a few days later I bumped into another small Heliogomphus in Gia Lai Province. Outward it was a little different in coloration. Notably, the superior appendages were more extensively white and S7 had a distinct anterior pale yellow ring. With differences between Heliogomphus species often slight, I thought it might be a different species, but checking it under the microscope I cannot but conclude the appendages and vesica spermalis are identical. If so, the slightly different coloration is likely nothing but a geographical variation. I concluded that the Gia Lai specimen is also H. chaoi. That species is therefore much more widespread than previously thought.

Heliogomphus chaoi in Bao Loc. Note it only has on S7 a pale yellow line along the dorsal carina and a lateral basal spot.
Another male at the same location
And the appendages in dorsal view
Heliogomphus chaoi at Gia Lai. Note the small yellow dorsal spot on S8 and the large anterior yellow ring on S7. But structurally it is not different.
The appendages in dorsal view, the white more extensive