Loose ends

So, wah loose ends remain from the mid-summer road trip around northern Vietnam? In Pia Oac in early July I ran into a whole bunch of small gomphids one afternoon. The turned out to be Davidius. But which species? There has been some confusion about Davidius fruhstorferi, with various subspecies described and some split as separate species, or lumped again. Clearly, this species belongs in the fruhstorferi corner, but the thorax pattern is a little different, it is a little smaller and the appendages, although similar, are not excavated laterally and smaller than in the specimens I saw in early spring at Yen Bai. Now, it is possible that indeed this is subspecific variation, but I am not so sure. It would not surprise me if in fact this turns out to be a different Davidius. Nevertheless, for the time being it look as if it will go down in history as Davidius cf. fruhstorferi.

A tiny gomphid, and please note the nice black square mark laterally. But let's pretend it is Davidius fruhstorferi, a male

Then this is the female. And clearly the square mark is not a fluke. All individuals, including this female, displayed that characteristic, which I have not been able to find in any description of any subspecies.

In copula, working to produce many little gomphids

A female in dorsal view. Along a tiny stream in the forest it was quite common

What else do I still have to show from my odyssee? A yes, Leptogomphus elegans. Known from Ba Vi and from Pia Oac only in Vietnam and indeed, after seeing it in Ba Vi, I now ran into a single mail in Pia Oac.

A nice male Leptogomphus elegans. At this angle it is hard to tell, all Leptogomphids look the same, basically.

But like this is it very clear! Leptogomphids can reliably be identified on the basis of their appendages.

Still more? Yes, forgot to mention one of the few Libellulines that I took a picture of: Libellula melli. It flew at the Love Waterfall in Sa Pa middle of April and it was still there July 2. At least one male.

Male Libellula melli, nice species that reminds me of home, because it looks a lot like L. depressa.

Anything else? Yes, yet another gomphid. Phaenandrogomphus tonkinicus, found at the end of May for the first time in Xuan Son National Park, turned out to be a common species in medium sized rocky currents. I saw it many times in Bac Kan and Cao Bang provinces. Many females were seen ovipositing in Pia Oac.

This is what the female looks like, pattern much like the male

And Phaenandrogomphus tonkinicus male. Hovering for prolonged periods over the little sandy spits where the females would come to oviposit, but with terrible timing, as invariably he was there when they were not and vice versa.

And that, dear readers, concludes the report on damsels and dragons from the northern provinces in late June and early July.

Phaenandrogomphus tonkinicus

Saturday May 31 I was checking the streams of Xuan Son National Park. It was rather cloudy and around 4 pm it started to rain. As it cleared a bit, to my surprise several gomphids came out. With Lamelligomphus camelus a smaller gomphid appeared, that interacted with L. camelus actively. It had light-colored appendages and showed the same hovering behavior as L. camelus. I really wanted to know what it was, but hit the water with the net and gone it was. It became darker afterwards and nothing showed (apart from Macromia, on which later more). The next day I returned at the end of the afternoon. Nothing showed near the bridge, so I went into the forest. To my surprise when I returned quite late several gomphids were hovering over the water near the stone bridge. There stayed until it was almost dusk. Apart from Lamelligomphus, again there were several of these lovely little gomphids around. I was able to catch one this time, for inspection and later also saw a huge water spider carrying a female around. I fought the spider and came out victorious. Too late obviously for the female, but her body will serve science. There is some consolation in that, if not for her, then for me.

Checking literature it slowly became clear that this is Phaenandrogomphus tonkinensis. Described by Fraser in 1926, again by Lieftinck in 1969 and Wilson (2009). The latter clarified the conspecifity with P. chaoi. This is a very variable insect, as can already be seen from the photos below. No surprise that when describing species from a small sample, this could easily lead to mistakes. What for instance of P. yunnanensis? Be that as it may, I was happy with this beautiful addition.

Phaenandrogomphus tonkinicus, male. This one with extensive markings on the dorsum of the abdomen and a very thin humeral stripe.

Another male, less light on the dorsum (no central spot on S6), but thicker  humeral stripe connected to humeral spot

The unfortunate female, killed by spider and liberated by me

Another male in hand, note almost absent humeral stripe

Very typical constellation on S2

Fabulous appendages in lateral view

And in ventral view

And finally the strange lamina of the female in ventral view