Asiagomphus mayhem - Vietnam is the place to be

August 2018 I finally was able to publish the results of 4 years of chasing Asiagomphus species in Vietnam. The paper that appeared in Zootaxa that year provided information on 8 species from this diverse genus. Asiagomphus acco is one of the easy species to recognize and had been recorded from Vietnam before. It is widespread and I published it on the blog long ago. Another species that is, at least in hand, easy to recognize is Asiagomphus reinhardti, which had only recently been described from neighboring Cambodia. The male has highly distinctive appendages, quite different from all other species in SE Asia. I found it both in Lam Dong Province and in Gia Lai Province. Here is an example in hand.

Male Asiagomphus reinhardti, caught May 17, 2016, near Bao Loc

As pointed out elsewhere in the blog, the most widespread species of Asiagomphus in northern Vietnam is probably A. auricolor. The original description by Fraser was based on a female and it had been hard to match it with its female. In my paper I give a first description of the male and provide further information on the female. Photos of this species are included already on this blog in past entries.

In neighboring Thailand Asiagomphus xanthenatus occurs and I was able to verify the occurrence of this species in central Vietnam, where I one lucky day ran into three males. Here is a photo of one of these.

Asiagomphus xanthenatus male, May 15, 2016 from Quang Nam Province.

Near Da Lat in Lam Dong Province, not that far actually from where I collected A. reinhardti (Bao Loc), I found a new species to science, Asiagomphus kosterini, which I reported already in this blog. 

That leaves us with 3 more species. One of these is a species with longitudinal stripes on the abdomen, different from all other species in Vietnam, although this pattern occurs on many of the northern species. This is Asiagomphus pacificus, which I found in Cao Bang Province and Bac Kan Province in the north. I reported this species already previously within this blog.

Which leaves us with two tricky species that I also already showed on the blog. Both turned out to be new to science and both are rather similar to some of the other species shown in this entry. These are Asiagomphus superciliaris and Asiagomphus monticola. Here are examples of both.

Male Asiagomphus monticola, Yen Bai Province, June 1, 2014

Asiagomphus monticola male, Xuan Son NP, May 31, 2014

And finally Asiagomphus superciliaris, Huu Lien Nature Reserve, May 24, 2014

Comparing the photos of these last three species, all similar to A. auricolor too, may leave the casual observer somewhat bewildered. Indeed, these species are rather difficult, if not impossible, to identify in the field without in-hand inspection. The details of the caudal appendages and secondary genitalia provide good clues. If you carry a copy of my Zootaxa paper, which provides these clues, you should be able to identify them and release them again.

A new species of Asiagomphus*

*Updated January 1, 2020 based on the publication in 2018 in Zootaxa of my study of the genus Asiagomphus in Vietnam, which included the description of this species as Asiagomphus kosterini.

April 17 I was checking streams near Tuyen Lam Lake at Da Lat. It started as a sunny day and around 9.30 I spotted the first gomphid, perching in the middle of the stream on a stone. It was immediately obvious from the extensive yellow on the terminal segments that this was something I had not seen before. It took some effort, but eventually I was lucky enough to be able to net it. In hand my suspicions that it was an Asiagomphus species were confirmed. A very interesting species, with extremely extensive yellow markings and widely expanded S7-9. Patterning was otherwise in line with Asiagomphus and the appendages were also typical of the genus. But it is not any of the other 4 species (at least) I have seen in Vietnam and it is not any of the known species from South-East Asia either. A wonderful species and new to science! It was rather common at the stream, with at least 10 different males observed and a few females seen ovipositing.

I eventually published this species as Asiagomphus kosterini, one of a total of eight species of Asiagomphus I could confirm in Vietnam.

Asiagomphus kosterini. Note the extensive yellow markings on S7-9. A beautiful and striking species.

A male in dorsal view, showing the massive club

And in lateral view

The appendages and terminal segments in dorsal view

Asiagomphus pacificus - finally (a lot of) males

*This entry was updated June 25, 2018. New insights into the differences between A. hainanensis and A. pacificus now lead to the conclusion these are A. pacificus.

May 19 I was checking a river close to Cao Bang city when I ran into at least 10 males of Asiagomphus pacificus. This species I discovered new for Vietnam last year at Bac Kan at a site that has since been destroyed. What is more, I only found one single female, leaving room for discussion. But these males are very obvious and also show that this is certainly a species that is more widespread in northern Vietnam.

There are at least 4 species of Asiagomphus in Vietnam, but the problem is species of this genus are very similar, both in outward appearance and in appendages. The easiest is arguably Asiagomphus acco, with its dorsal tooth on the superior appendages. Asiagomphus sp. novum is also relatively simple, with the epiproct V-shaped, see the entries. Asiagomphus auricolor is apparently rather variable. I also consider it a candidate for what currently is identified as A. xanthenatus in Laos. A. auricolor has sometimes two and sometimes three lateral stripes and the female more or less yellow on S1-2. A. pacificus has longitudinal stripes on the dorsum of the abdomen, quite different from the rings of the other three. It also often has a spot on S8, which really helps the ID.

Asiagomphus pacificus, finally a male. Note the oval lateral spot on S8. The humeral stripe can be much clearer.

The same male at a different angle. Note the longitudinal markings along the dorsum of the abdomen, all the way up to S7.

Another shot of the same male

A different male, without the oval spot on S8 and with more extensive humeral stripe.

First visit to Huu Lien in 2015 - Trigomphus* **

*This entry was adjusted slightly after publication of the description of Trigomphus kompieri Karube, 2015
**And again after publication of Paracercion ambiguum Kompier & Yu, 2016

Sunday March 22 was supposed to become a sunny day. Sadly, the weather forecast is not very reliable in Vietnam, but after a very cloudy morning I did have some weak sunshine in the afternoon, just enough for things to become a little more active. Last year in April I had found a new species of Trigomphus in Huu Lien, but by then it was already scarce, as Trigomphus is an early genus (season-wise). I wanted to take some better photos of it, so for the first real dragonfly trip in northern Vietnam of the season I headed for Huu Lien. In the morning I saw two males and a female, but they did not linger. When the sun came out in the afternoon they showed better, but sadly no female anymore. This Trigomphus species is the most southerly (apparently) of the genus and with the broad dark line of the flanks quite exceptional. A lovely gomphid. It has recently been described by Haruki Karube as T. kompieri.

I was able to see 31 species over the day, not bad, given that the weather was not good and it is only March. Highlights included 5 freshly emerged Asiagomphus, likely A. auricolor, 3 Epophthalmia elegans, Anax guttatus, and Paracercion ambiguum.

Beautiful Trigomphus kompieri, male

Another male perched by the side of the stream

Same male as in the previous photo, perched this time on a snag 

A common species, but handsome, Trithemis aurora, female

Copula of Pseudagrion microcephalum, one of three Pseudagrion species observed today

Already subject of the blog on many occasions, yet another photo of the pretty Paracercion ambiguum.

One of five freshly emerged Asiagomphus, likely auricolor.

Asiagomphus pacificus - new for Vietnam

*updated 25 June, 2018. See the other entry on this species.

I have been looking carefully at Asiagomphus species this year, after it became clear there are more species here than just beautiful Asiagomphus acco. In spring in Huu Lien I was able to collect two unknown species, one of which I now believe is the long missing, but in fact common, Asiagomphus auricolor. Asiagomphus species B likely is an as yet undescribed species. What these species share with A. acco and related A. xanthenatus is that they do not have the longitudinal arrow markings on the dorsum of the abdominal segments, but rather have transverse bands marking the borders between the segments. In A. acco these are much reduced in the male, but present in the female.

When on June 24 I caught a female Asiagomphus along an otherwise also very productive stream in northern Bac Kan Province, it was immediately clear to me that this was one of the Chinese species and not any of the species I had seen in Vietnam so far, because of exactly these longitudinal markings on the abdomen. The shape of the occipital ridge and the lateral markings on S2-4 helped clinch the ID as Asiagomphus pacificus, an addition to the Vietnamese list, but a species widespread in neighboring China.

To my shame and regret, I did not take proper photos of the dorsal view of the abdomen in the field, nor back at the room we stayed in at Ba Be National Park. Therefore the dorsal pattern is difficult to see in the accompanying photos taken of the preserved specimen.

Asiagomphus pacificus, female, Bac Kan Province, June 24. Note the lack of transverse bands on the abdomen (apart from S7, the pattern of lateral spots on S3 (two), the humeral spot and largely yellow metepisternum.

Detail of S2-3

Longitudinal markings on the dorsum of abdominal segments

Facial pattern and shape of occipital ridge

Asiagomphus auricolor - saved from oblivion*

*Updated January 1, 2020. In August 2018 I published a study in Zootaxa of all known Asiagomphus species from Vietnam. In it, I also offer the first official description of A. auricolor and describe several very similar species. I maintain the below entry as I first wrote it, but would like to suggest to readers interested in Asiagomphus species in Vietnam to peruse the paper, which provides the best and comprehensive overview of the genus in Vietnam to date (if I may so say, which, of course, I may).

Do & Dang mention only two species of Asiagomphus for Vietnam. One is a regularly encountered species in northern Vietnam, Asiagomphus acco, and the other is known from only one female specimen described by Fraser in 1926 as A. auricolor. The genus itself has at least 23 species, quite a few of which occur in neighboring countries. It therefore came as no surprise when in the spring of 2014 we found two species of Asiagomphus in Huu Lien (see the blog entries both here and in Sebastien's blog). We called them Asiagomphus sp. A and Asiagomphus sp. B. A few females were collected, but they did not seem to fit the description of A. auricolor. As spring turned into summer, species A was found "all over the place", that is, I myself encountered it in Yen Bai Province, in Cao Bang Province, in Lang Son Province, in Phu Tho Province and in Bac Kan Province and Sebasien also ran into it at various locations. Although the males are rather variable, with a more or less prominent humeral spot and with extensively marked yellow metepisternum to completely unmarked black, structurally they are all identical. The females are characterized by two horns or varying size over the lateral ocelli and another horn in the middle of the occipital ridge.
What species A and B and species like A. xanthenatus (from Thailand) and A. acco from Vietnam have in common is that the abdomen has transverse bands on most segments. This is completely different in the species from mainland China, from Hainan and Taiwan or from Japan, which invariably have longitudinal markings on the dorsum of the abdomen. This trait is also visible on that other species recorded in the region, A. auricolor.
Something else intriguing is the amount of yellow on S1-2. This is very extensive in A. acco, rather prominent in A. xanthenatus and also very extensive in the description of A. auricolor. In species A at least there is a lot of variability, with some females, as we will see, with almost entirely yellow S1-2. But I am getting ahead of myself. For now, suffice it to say there are several species in northern Vietnam characterized by transverse yellow bands on the dorsum of the abdomen: Asiagomphus acco, Asiagomphus auricolor, Asiagomphus sp. A and Asiagomphus sp. B. Moreover, at least A. acco and Asiagomphus sp. A are widespread and common. This latter fact is rather surprising. Somehow this species has eluded the sampling of visiting entomologists, even if it is widespread and common.

Let's turn to the enigmatic A. auricolor. Fraser (1926) describes it as follows:
"Gomphus auricolor sp. nov., (Fig. 4, a). Female. Abdomen 45mm. Hindwing 40mm. Head glossy black, the bases of the mandibles and a broad transverse stripe over the upper surface of frons bright citron yellow. Prothorax black with an anterior collar, a geminate spot on dorsum and a large spot on each side bright citron yellow. Thorax black marked with bright citron yellow as follows: - a short, broadly interrupted mesothoracic collar, a broad, parallel, antehumeral strips broadly confluent with  the collar below. Laterally entirely yellow save for two narrow black lines, one traversing the spiracle, the other on the posterolateral suture, confluent below and cutting off a spot of yellow at lower border of thorax. Legs entirely black; hind femora with a row of gradually lengthening, closely set, short spines. This femur extends to middle of segment 2. Abdomen black marked with yellow as follows: - segments 1 and 2 almost entirely yellow, segment 1 has only a small sub dorsal tuft of short black hairs on each side. whilst 2 has a small semilunar, middorsal apical black spot, segment 3 with only a fine linear later-basal yellow stripe, 4 with a tiny basal point, 5 to 7 with large bass-lateral bright citron yellow spots nearly confluent over the dorsum, 8 unmarked, 9 with its apical half yellow, 10 unmarked. Anal appendages pale, small, conical. Vulvar scale not visible. Wings hyaline; a basal subcostal nervure in the right forewing of one specimen only: 5 rows of postanal cells; pterostigma pale brown, over 5-6 cells, braced; nodal index 15-18/14-11 | 17-15/12-14; remainder of venation typical for Gomphus."

The few females caught for species A did not have all yellow S1-2, as described for A. auricolor. They also did not have the yellow spot on the dorsum of the head Asahina described for A. xanthenatus females. However, as it turns out, the females are also variable, just like the males. On June 26 we found a nearly dead (due to age) female specimen with almost completely yellow S1-2. Almost simultaneously Sebastien published photos on his blog of another female, likewise with almost completely yellow S1-2. Both shared the three horns also seen in less extensively yellow females associated with Asiagomphus sp. A males. It occurred to me that this all made sense. It would be rather strange that there is a common Asiagomphus species all over northern Vietnam, but that Fraser would describe a different species that just so happens to be a one off and never to be seen again different species. Checking the specifics of this old female against the description, it seems to close a match to ignore.
Its abdomen measures 47mm and the hindwing 40mm. It has an all black face, with unmarked labrum, but with pale bases to the mandibles and with traverse line over the top of the frons. The prothorax is marked as described for A. auricolor, but this matches with many species, just as the thoracic markings (no humeral spot or stripe, extensively yellow on metepisternum). But the markings on the abdomen are an exact match with the description. S1-2 are yellow but for a patch of black hairs sub dorsally on either side of S1 and S2 has apically a black semi-lunar mark. Likewise, the markings of S3-10 match. The wing formula is close enough (15-18/17-12 | 19-16/13-16). There are also some differences. The vulvar scale, although small, is visible, the spines on the legs seems not as densely spaced as the description seems to suggest and the appendages are blackish, not pale. Nevertheless, Asiagomphus species with such extensive yellow S1-2 (shared only with A. acco) are rare and it is rather unlikely that this is not A. auricolor. The differences can be explained away due to the small sample size of the description (one or very few (Fraser speaks of the right forewing of one specimen only, as if there were several. Another female collected near the first had less extensive yellow on S1-2, but more on S3 and also had pale appendages).

If these specimens can be recognized as A. auricolor, then so should the less clearly marked yellow specimens and of course all the males. The females can then be recognized by the combination of thoracic and abdominal markings combined with a small horn on the occipital ridge and in most cases two prominent additional horns over the lateral ocelli. The males can be recognized by the shape of the hamule and inferior appendage in ventral view (wide U-shape) in combination with all black labrum. Nevertheless structurally they seem very close to A. xanthenatus as illustrated by Asahina and future research may well point out that xanthenatus and auricolor are closely related or even co-specific.

One of several males caught close to the Asiagomphus auricolor female. This male has particularly extensive yellow on S1-2, an intermediate amount of yellow on the metepisternum, and humeral spots.

Two males caught together with the Asiagomphus auricolor female. They have the typical traverse abdominal markings and structural characteristics of Asiagomphus sp. A. Bottom right is the Asiagomphus auricolor female.

Normal female of Asiagomphus sp. A, aka Asiagomphus auricolor. Seperable from A. acco by the humeral spot, small amount of yellow on metepisternum, black dorsum to S1-2 and larger traverse markings on abdomen.

The specimen that links Asiagomphus sp. A to Asiagomphus auricolor. Note the massive amount of yellow on S1-2, with only a tuft of black hair subdorsally on S1 and small black semilunar marking at the posterior margin dorsally. Note extensive yellow on metepisternum to separate from A. acco, but lacking humeral spot, dark appendages, both indications of the variability in the appearance of the females. This female is identical in the markings of thorax and abdomen as the female from Xuan Son featured in Sebastien's blog (see http://vietodonata.blogspot.com/2014/06/some-nice-stuff-not-far-from-hanoi.html)

But all females share a small horn on the occipital ridge and variable horns over the lateral ocelli.

Some Asiagomphus specimens from Xuan Son and Yen Bai*

*This entry was adjusted on January 1, 2020, following the publication of my paper in Zootaxa in 2018 on the now eight species of Asiagomphus known from Vietnam. The original entry treated the specimens illustrated as variants of A. auricolor. This was erroneous. They have now been published as a new species: A. monticola.

This posting shows variations of Asiagomphus monticola. Please see my article in Zootaxa for a full description of this species and its diagnostic characters. It is very similar to A. auricolor, A. superciliaris and A. xanthenatus, which are all also known from Vietnam.

Asiagomphus monticola from Xuan Son

Close-up of thorax and head

Facial pattern

Asiagomphus monticola from Yen Bai, different pattern, same structural characteristics

Scan of two specimens from Xuan Son

Same for Yen Bai specimen

Xuan Son specimen appendages ventral view

Xuan Son specimen dorsal view

Yen Bai specimen ventral view

Yen Bai specimen dorsal view

Asiagomphus acco - a great species

Asiagomphus xanthenatus acco was described as a subspecies of A. xanthenatus by Asahina, but the rather different appendages prompted its elevation to specific status (Do Manh Cuong, and see also Karube). I saw it once last year, in Ba Be, towards the end of July. I was very happy to renew my acquaintance with it, when on May 18 I did not see one, not two, but many at about 300m asl in Tay Thien (Tam Dao). Here a few shots.

The male of Asiagomphus acco, with extensive yellow S1-2 and black S3-8.

Dorsal view of appendages

And lateral, note the tooth halfway on the venter of the superior appendage

And in ventral view

Asiagomphus, two different new species?*

*This entry was adjusted on January 1, 2020. In August 2018 I published an article on Asiagomphus species in Vietnam in Zootaxa. By then I had verified 8 species of Asiagomphus in Vietnam, several of which were new to science and others were not previously recorded from the country. I did not want to change the 'historic' entry below that reflects my first ramblings when confronted with specimens of this tricky genus in Vietnam, so I left it as it is, but added the proper scientific names for the species involved between block-marks. (These are Asiagomphus auricolor and A. superciliaris.)

I already posted on an Asiagomphus species occurring at Huu Lien Nature Reserve. Until now I only had a female in hand. Useful, because the horn on the occiput immediately helped to eliminate most possible species. It was however pretty much impossible to say more on the specific identity.

On May 1 I went again to Huu Lien with the objective of catching the male. I saw a great many (15+), but this is a wary and large insect and I was clumsy too, so it took a while before I finally was able to catch one.

Later that morning I ran into another Asiagomphus male, perched on a stone in the stream, something the other Asiagomphus had not done, always sitting on leaves and branches over the water or hovering and patrolling above the stream. It seemed smaller and darker. And luckily this one specimen was not as difficult, to I was not that clumsy, or both. Anyway, I was able to catch it.

With this, trouble only started. It is clearly another species, but which one? Interestingly, both males share the pattern on the abdomen with transverse yellow lines at the sutures between the segments, and do not have longitudinal lines. The also lack a antehumeral stripe, and the second male even a spot. This is a pattern shared with A. xanthenatus acco [= Asiagomphus acco], which otherwise of course is very different, with a ventral tooth to the upper appendages and largely yellow S1-2. For now, I am at a loss. There seems to be no direct hit with any of the known species in the larger region. The occipital pattern of the female rules out most species for species 1 and species 2 is so dark, it is also different from any others. Of course, most species display quite a bit of geographical variation, or in the details of the appendages. This does not make things easier, but my hope is that scholars with experience of many of the Chinese species may be able to say something on the subject. My gut feeling however is that these are both undescribed species.

Possible species in the area include A. auricolor (Fraser 1926, only one female known, I do not have the description, but it is apparently from "Tonkin")*, A. hainanensis, A. pacificus, A. pacatus, A. perlaetus, A. septimus, A. takashii, A. giza, A. xanthenatus acco and A. x. xanthenatus. I have no match. Suggestions are very welcome.

Measurements:
Species 1 TL 63mm, Abdomen (+app) 47mm, HW 39mm
Species 2 TL 57mm, Abdomen (+app) 41mm, HW 33mm

* I received a copy of Fraser courtesy of Matti Hamalainen. The synthorax pattern of the female in the description is reminiscent of species 1, but lacks the antehumeral spot. The measurements are also off (abdomen length 45mm, mine 50mm). It has all yellow S1-2. Therefore species 1 is not A. auricolor [subsequently I could establish that it is].

To fresh up our memory, the female of Asiagomphus species 1 [=A. auricolor], with two horns over the lateral ocelli and one on the occipital ridge

The vulvar lamina of the female Asiagomphus species 1 [=A. auricolor]

Asiagomphus species 1 [=A. auricolor], with antehumeral spot, large posterior hamulus, second lateral stripe, lots of yellow on S1-2

Asiagomphus species 2 [=A. superciliaris], no antehumeral spot, no second lateral stripe, small posterior hamule, S1-2 dark dorsally

Here the two species scanned in dorsal view. Species 1 [=auricolor] is on the top left.

Species 1 [=auricolor] appendages in dorsal view

Species 2 [=superciliaris] appendages in dorsal view

Species 1 [=auricolor] secondary genitalia, note especially posterior hamule

Species 2 [=superciliaris] secondary genitalia, much smaller posterior hamule with inconspicuous hook

Species 1 [=auricolor] appendages in ventral view, very widely separated inferiors in broad basin like U-shape

Very different inferior appendages, shallowly cut in V-shape [=superciliaris]

Species 1 with stump superior appendages [=auricolor]

Species 2 with sharp point to superiors [=superciliaris]

Species 1 [=auricolor], black labrum. Note the flat area between the two bumps behind the ocelli

Species 2 [=superciliaris], black labrum. Note the gentle V-shape between the two bumps behind the ocelli and the hump on the occiput

The problem with penises. They all look alike. Species 1 [=auricolor], distal segment

Species 2 [=superciliaris], distal segment