Monday, 2 June 2014

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



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