Melligomphus sp. nov. ?

On July 23, as is known by now, I found myself in Ba Be National Park, happily checking a stream with gomphids left and right. There were several Lamelligomphus camels, or so I thought, hovering above the stream, a bit like some Phyllocycla species do in Rio de Janeiro, but that is another story. I caught one specimen and made some record shots in hand. Now, working on the photos, I had another look and lo' and behold, it did not look like Lamelligomphus at all, so I checked it against another specimen I collected in Tay Thien, and lo' and behold indeed, it was different. What is more, that species was a Lamelligomphus, but not L. camelus either. The plot thickens...
The Ba Be specimen was Melligomphus ardens, or was it? As can be seen on the photos S8 does not have a pair of humps, it only has a tuft of hairs centrally on the dorsum of the segment. And now we come to think of it, the metepisternum should have a stripe, but it is reduced to just two tiny yellow elongated spots. This could be individual variation. Wilson & Xu 2009 also give an elongated 5th cel in the anal triangle, absent in this specimen and there seem other differences in the appendages too. Enough to raise an eyebrow! Better go back next year.

As a postscript, the other Melligomphus species all seem to have the antehumeral stripes separated from the collar, unlike M. ardens. Chao does not give the 5th cell in the triangle.

Melligomphus sp. nov. , male

The appendages, but note the dorsum of S8, a tuft of hair, but no humps!

Another view of the last segments