Thursday, 24 July 2014

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.

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