Two new Rhyothemis species from Phu Quoc

On April 12 to 15 we visited Phu Quoc Island to see a few of the dry season specialties. This year is exceptionally dry and the island suffers from break-neck speed development and ground water abuse, but I was able to locate many of the goodies that I hoped for, although not all. Amongst these were two Rhyothemis species that I had not recorded before. One of these is known to occur in the island and although numbers are low, I bumped into it at a handful of widely separated locations. This is the smallish and wonderful Rhyothemis obsolescens.

The other I did not recognize. At a pond in the forest on several days I observed a male Rhyothemis perched that looked a lot like R. plutonia, but the greenish iridescence on the wings seemed more extensive and the remarkable purple of that species was missing. The wings seemed to have a reddish ground colour and towards the tip the greenish colour was visible as dots too. I tried to catch it, but I could not. In the end it dawned on me that this is Rhyothemis aterrima. This species has been recorded in Vietnam before. Cuong & Hoa list a record by Asahina from Binh Duong Province from 1962. But I know of no other records. Supposedly it is not uncommon in for instance Malaysia, but it is difficult to find photos on the web, so maybe it is actually not that common. I am very happy with it.

This is the wonderful male of Rhyothemis obsolescens. The pale borders to the wings give them a sort of out of focus aspect.

From below the golden shine is missing, but the brown and paler areas form a beautiful pattern. It excels at holding its wings at different angles.

Although this specimen takes a more conservative pose.

This is the difficult Rhyothemis aterrima male. This photo is a little too dark and therefore it looks quite a bit like R. plutonia. But note the relative slender hinds wings, extensive green and lack of purple.

Much more apparent in this photo is the reddish ground colour of the wings and it can be clearly seen that the green on the outer wings forms distinct dots.

Flashback - trip to Cat Tien NP 6-9 February 2015

In early February we spent a few days in Cat Tien National Park. It was very dry. Not a drop of water in the forest - virtually. But the fishponds were still productive and the odd stream or trickle also provided some species, but everywhere in low numbers. Clearly middle of the dry season is not the best time for Odonata here. Consequently we did not find anything new for the park list. But some species were very present and one was Gynacantha basiguttata, of which we saw several along the road through the forest, now adults.

Another species that I had seen only once, and that previously eluded photographic capture, was Rhyothemis triangularis. I was able to take pictures of a freshly emerged specimen.

And lastly, one evening, as I was heading back to the lodge, I ran into a roost of Potamarcha congener. An exceptional spectacle!

Gynacantha basiguttata female, now fully mature. Note the dark smudges at the base of the wing along the subcosta.

The face of the same female

A little extra: male Agriocnemis nana. I saw only a few, but what a delight.

Roost of Potamarcha congener. How many in the photo? I count at least 50.

Fresh male Rhyothemis triangularis, the only one seen.

Rhyothemis species from Cat Tien National Park

There are four species of Rhyothemis at Cat Tien, but R. triangularis was sadly absent and I therefore failed to get pictures of that lovely species once again. Other species were less common than they had been in July-August. I saw only a single R. plutonia.

Male Rhyothemis phyllis, a lovely species with reduced black-and-orange pattern on the inner wing.

R. plutonia is a fantastic species that looks pretty much black from a distance, but under close inspection reveals green and purple on the inner wings.

Finally, a female of R. phyllis. Possible to confuse with R. variegata, but black-and-yellow pattern much larger and extending far onto the outer wing on that species.

Rhyothemis phyllis

During my week at Cat Tien in early August I saw 4 species of Rhyothemis. That is a treat for someone living in Northern Vietnam, where only R. variegata is regular. I did see R. plutonia in Huu Lien, but that is it. In Southern Vietnam both these species occur, but they are joined by R. phyllis, reasonably similar to R. variegata, and by R. triangularis. To my shame I saw the latter only once, at the fish ponds, fluttering between a couple of trees at the edge of a pond. When I had my camera out, it had disappeared, so not even a record shot. R. plutonia was common here too, as was R. phyllis, a species that could be seen anywhere, although not abundant. It is a nice larger species.

Male Rhyothemis phyllis, with clear basal markings to the inner wings, but remainder, apart from the apex, hyaline

Two supercool additions to my list from Huu Lien

Saturday May 24 I drove to Huu Lien Nature Reserve. In the heat one of my tires blew out while I was parked along the road, presumably. It was quite a thing to replace the tire in the blazing sun, but the day made up for all that.

I had discussed with Sebastien the lack of Rhyothemis species in northern Vietnam. We always only see R. variegata. Nice, but there are other species out there, maybe. Indeed, today I ran into one. And not just once, I saw at least 6 males and 1 female. Rhyothemis plutonia. A marvelous species. I only managed some far away shots, but happy to at least have a record of them.

Rhyothemis plutonium, male

The same male, different pose

The second species I ran into when it was so hot that hardly any dragonflies were out and about. Along the stream in the half open area that once was (not so long ago) solid forest I noticed a massive dragonfly sitting. I took some far away shots before catching it for a few in-hand photos. This was Megalogomphus sommeri. Giant hooktail, what is in a name….

An awesome gomphid, Megalogomphus sommeri, male.

Same male in hand, allowing some close-ups

Appendages in dorsal view

Appendages in ventral view

And finally in lateral view, awesome, giant hooktail

Interesting detail of S7, hairy, and apical portion of S6, hairy

Rhyothemis variegata

There are at least 4 species of Rhyothemis in Vietnam, but one is very common and widely spread and this is the one species I have so far encountered in the north of Vietnam. The sometimes very similar R. phyllis occurs for instance in the Mekong Delta, where indeed I have seen it. But alas, no pictures. Rhyothemis variegata on the other hand can be quite easily encountered, even close to Hanoi. It is especially common in the foothills and we saw many near Van Long, where below photos of males were taken early September. The female was caught at Tay Thien, Tam Dao National Park, late August. These endlessly fluttering beauties apparently are the reason that Sebastien Delonglee got into dragonflies. Well, there is something about them...

Rhyothemis variegata, male

And another male, with typically front and hind wings at different angles

Rhyothemis variegata, female