April 2 - Huu Lien and first gomphids

April 2 was a nice spring day to look for the first gomphids of the season in Huu Lien Nature Reserve. As always, the first impression was of clearance progressing, but like last year end of March, Trigomphus kompieri was about at various locations. The first I bumped into was a female, but like last year, I could not catch it and did not get a picture! Trigomphus is genus of early gomphids. Paragomphus may actually be year round, although rare in the winter, I think they may be around. Anyway, there was a male about too, interacting with the Trigomphus. I also saw quite a few Paracercion melanotum and fully mature Gynacantha subinterrupta. Below a few photos.

The first male Trigomphus kompieri of the day, a little difficult to get a clear shot.

And the third. Somewhat easier. The second eluded the camera.

Paragomphus capricornis against a muddy stream background.

Paracercion melanotum male

And Gynacantha subinterrupta showing well

Trigomphus carus - a new species for Vietnam

Saturday April 4 it was an absolutely lovely day and I woke up very early for birdwatching in Pia Oac. When the sun became hot I went to a lower area on the mountain and checked also some streams and a small pool by the roadside. It was here around noon that I noticed a small gomphid perched on a blade of grass over the pool. I was taken aback by it. From a distance its pattern reminded me of Davidius species, but after a quick photo I was able to catch it and in hand quickly concluded it was a Trigomphus species. Only a few minutes after I had taken it another landed on exactly the same blade of grass. Because these are difficult and variable species and because it was a new species to Vietnam for sure, I took this male as well.

There are 14 known species of Trigomphus, although the true number may be smaller, with several synonyms in use. (The 14th is the new species from Vietnam I found last year, which will be described by Karube in an article to be published in May this year*). The particular thorax pattern, shape of appendages and of the genitalia all fit very well Trigomphus carus, a species only known from Fujian in China, as far as I can tell.

This species has the dorsum of the thorax marked by thin "7" shaped stripes and a small antehumeral spot. In fact as is often the case, this character is somewhat variable. One specimen has it, the other does not. Also there is some variation in the lateral thorax pattern. Shape of posterior hamulus is rather distinctive for T. carus and also the somewhat triangular outline of the anterior hamulus is indicative. The inferior appendages, interestingly, curve outward slightly, whereas in most species they curve inward. The match in appendages, anterior and posterior hamulus and penile organ, plus the close match in pattern of the thorax and size (one specimen has abdomen 37 and HM 30mm, the other 36 and HW 29mm), makes identification as Trigomphus carus possible.

* Described as Trigomphus kompieri in the May 2015 issue of Tombo

Trigomphus carus male as found, perched on a leaf 40cm above the water of a small pons

The same male, in hand. Note the anal triangle with 5 cells.

Both males scanned in dorsal view. Note the absence of the antehumeral spots in the top individual, which shows the sometimes limited use as an identification feature.

Both males in lateral view. The bottom individual with slightly less black on the sides of the thorax.

The face of Trigomphus carus, with all-black labrum.

Appendages in dorsal view. Note the lateral process at two-fifths.

Close-up of the right superior appendage in dorsal view.

Lateral view of the appendages. Left side and right side not exactly the same.

Inferior appendages in ventral view. Characteristically slightly curved outwards. The orange bit is poop.

The ventral view of the hamuli. Note the bulging swollen posterior hamuli adorned with a crest-like inward-facing hook.

And lateral view of the hamuli. Here the "hollowed out" triangular anterior hamulus is essential.

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.

Huu Lien Gomphid enigma*

*Adjusted after publication of the Tombo May 2015 issue, in which Haruki Karube published Trigomphus kompieri.

Yesterday, April 21, I visited Huu Lien Nature Reserve and ran into 4 Gomphid species. Nihonogomphus schorri, after all it is the type location, and Ictinogomphus pertinax will not raise eyebrows. A small gomphid of which I saw 4 individuals should. It appears to be a Trigomphus species, a genus not recorded from Vietnam, although it has been recorded with several species from southern China. It has appendages close to those of T. succumbens, but the thorax markings and facial markings are rather different. Especially the thick black line along the metapleural suture, the so-called third lateral stripe, is strange. If correct, this species awaits description. Please see the below photos and if you know what it is, tell me. (It was subsequently established that this is a new species of Trigomphus, described as T. kompieri (Karube, 2015)

Besides, I also saw another, large, Asiagomphus. I was able to take some photos, but these do not show the abdomen tip. I doubt anyone will have the audacity to identify it on basis of the photo, but I add it at the bottom nonetheless.

The very, for a Trigomphus, blackish male of T. kompieri.

At about 45 mm not a large insect, for a Gomphid

Appendages in ventral view

More striking, because of the white color of the superior appendages, in dorsal view

Close-up in lateral view, of course upside down. This is the right side. The superior appendages have a large ventral tooth at 2/5th and a serrated distal edge, inferiors smoothly curved.

The left side, lateral view, this one uppers up and lowers down.

The right superior appendages in dorsal close-up. Ventral tooth also visible as lateral tooth, but it is one and the same.

The other, large, enigmatic Asiagomphus. Note the narrow lateral yellow stripe.