A few more goodies from Xuan Son

October 26, in Xuan Son, I had, besides the Calopterygids and Planaeschnids, several other interesting dragonflies. Rhinagrion hainanense is always a great find. Regular at Xuan Son from early spring until autumn, but a wonderful insect. I was also surprised to see a female Merogomphus pavici ovipositing. I had no idea this species flies this late in the year. And two males Lamelligomphus formosanus were another surprise. Of course some Lamelligomphus fly relatively late in the year, but I had not seen L. formosans this late. Boyeria karubei was common, but it is a fine species and a specialty of the park. I also took a few photos of Coeliccia. No less than 6 species were present: C. scutellum, C. pyriformis, C. cyanomelas, C. uenoi, C. sasamotoi and C. poungyi.

Old male Lamelligomphus formosanus, its venter covered in mites.

Pretty Rhinagrion hainanense, male

Female Boyeria karubei

Female Merogomphus pavici, resting after release

Merogomphus pavici, female face

Closer in-hand view. Note the massive hind legs and the spines on it.

Coeliccia poungyi, one of about 12 males

Male Coeliccia sasamotoi

Anisogomphus tamdaoensis - range expansion

Anisogomphus tamdaoensis was described by Karube (as Merogomphus tamdaoensis) from Tam Dao in 2001. We have found it since in Hoa Binh province and in Cao Bang Province. Today (August 16) I caught two females on Mt Mau Son in Lang Son Province. Clearly this species occurs over a wide range in Vietnam. Although these are females, I find no differences with several other females of A. tamdaoensis in my possession.

Both females, the older one on top, scanned under a kitchen plate, explaining the patterns around them.

The younger of the two, identical to the specimens of A. tamdaoensis, although some have yellowish wing bases.

A more aged female, the other found today

Merogomphus, Anisogomphus and Euthygomphus* **

*Updated on June 1, 2016 after publication of Anisogomphus neptunus
**Updates on December 15, 2016 after publication of the genus Euthygomphus Kosterin, 2016


There is one species of Merogomphus known from Vietnam. Merogomphus pavici is a large species, with distinctive appendages and markings. Euthygomphus parvus is a small southern species recorded from southern Vietnam that formerly was also included in Merogomphus. Then there is Anisogomphus tamdaoensis, described from Tam Dao, but at least also present at Ba Vi NP and in Hoa Binh Province and also originally included in Merogomphus.

During our travels at the end of June and beginning of July we observed Merogomphus pavici in Phu Tho Province (Xuan Son NP), in northern Bac Kan Province and in southern Cao Bang Province. This comes as no surprise, it is a widespread species.

Merogomphus pavici, male, from Bac Kan Province. Long legs indeed.

Another species we encountered was Anisogomphus tamdaoensis. A male was observed in Hoa Binh Province at Cuu Thac - Tu Son and what is very likely the female of this species was caught freshly emerged in Pia Oac Nature Reserve. It is safe to conclude that this species is much more widely spread than the rather restricted range of Tam Dao and Ba Vi.

Male Anisogomphus tamdaoensis from Hoa Binh Province, June 27

And its distinctive appendages in dorsal view

Female of presumably Anisogomphus tamdaoensis from Pia Oac, June 23.

However, now things get a little more complicated. In northern Bac Kan Province (and on June 28 also in Lang Son Province) we encountered several smallish male gomphids that at first glance seemed Euthygomphus parvus. Even at a second glance they did. It was only at a much later stage (today) that I realized they were in fact something else, namely Euthygomphus koxingai, a species known from southern China of which its occurrence in northern Vietnam is not at all surprising. It is uncannily close in outward appearance to E. parvus, which has a different penile organ. Also, in that species the antehumeral stripes are confluent with the collar. The appendages appear identical (see for instance the entry on E. parvus in the blog of Dennis Farrell). In his table of Anisogomphus Zhao (1990) uses the all black labrum of A. koxingai to distinguish it from other species, but as Wilson has pointed out, mainland China A. koxingai has in fact transverse yellow marks on the labrum (at the time of publication of their articles this species was still included in Anisogomphus).

Euthygomphus koxingai, male, late June Bac Kan Province

Another male Euthygomphus koxingai in the field

Appendages in dorsal view

In lateral view

And in ventral view

And finally, in Pia Oac I observed many Anisogomphus females that came to drop balls of eggs, almost always at the very same location and sometimes several females at the same time. They all came to a little sandy shallow area right under a rock, would drop eggs, fly up to perch on a nearby fern and produce another egg-ball to fly down and dip it and so on. These all shared extensive yellow both dorsally and laterally on the abdomen. They also had rather long vulvar lamina. I noticed photos on the web of seemingly identical female Anisogomphus from Thailand. Wilson (2005) mentions an Anisogomphus sp female from Guangxi that may also be closely related. For now, I can only treat this as Anisogomphus sp, unless anyone recognizes the species or until we can find a male. Strangely, although at least 20 females came to oviposit over the days I was in Pia Oac, no male was ever seen.

Female Anisogomphus neptunus in hand, Pia Oac Nature Reserve, early July

Another female preparing egg ball, this time not on a fern, but perched on a rock.

Close-up of abdomen, showing the extensive amount of yellow, both dorsally and laterally

Close-up of vulvar lamina

Anisogomphus tamdaoensis

Karube described a new species of Merogomphus from Tam Dao in 2001. Specimens were collected between May and early August. Subsequently the species was also found at Ba Vi. See also the blog entry on the blog of Sebastien Delonglee. Recently it was transferred to Anisogomphus. I was lucky enough to see a male on August 11 and a female on August 18, the male near Tam Dao Resort and the female along the stream at Tay Thien, also in Tam Dao National Park. The male and female both are reminiscent of the Leptogomphus species that are around (at least Leptogomphus perforatus, but seemingly more than one species is involved) and quite common, but the dorsal stripes are touching the collar, whereas in the Leptogomphus species they are not attached. Also, of course the male appendages are different and the appendages of the female or blackish, whereas they are whitish in the female Leptogomphus species. Also, the labrum of A. tamdaoensis is black, but it has two yellow spots in L. perforatus. Lastly, A. tamdaoensis has yellowish suffusion on the bases to the wings.

Anisogomphus tamdaoensis, male, eluding capture

The female, not so clever

Two other cool Gomphids on July 23

The gomphids of Ba Be encountered on the 23rd of July have been the topic of the recent posts and we have not come to the end of them! The same stream that produced Gomphidia kruegeri and Melligomphus sp. also had the following two Gomphidae.

The first is a common species, not particularly restricted to the prettiest streams. I also encountered it amongst the rice fields near Cuc Phuong, emerging from a ditch, and near Tam Dao. But it is a marvelous creature, this Paragomphus capricornis. The females have similar thorax pattern and the large abdominal rings.

Paragomphus capricornis, male

The other species is somewhat reminiscent of the North American Spiderlegs, because of its extremely long hind legs. This is the only time I saw it, so I do not know how common it is, but it is a widely spread species in Southeast Asia and called Merogomphus paviei.

Talk about disproportional legs! Merogomphus paviei, male

Close-up of thorax and head

Ventral view of appendages