Tuesday, 9 February 2016

Exciting new Gynacantha species for Vietnam (or the world?)

Middle December last year James Holden contacted me to report a spectacular Gynacantha species from Cat Tien National Park. Apparently it was quite common at a certain stream, where it could be observed in good numbers during the day time, flying across the stream. Photos showed a very interesting species indeed. The massive epiproct are only matched in southeast Asia by those of G. khasiaca, a rare Indian species that has almost never been observed, although there is a recent record from Bangladesh. The appendages depicted in Fraser (1936) are very similar, although there are in fact, if one looks closely, also differences. This may be due to the drawing, but maybe the differences are real. What is more, G. khasiaca has a grass-green thorax with spectacular dark stripes over the sutures, quite different from most species. The specimens from Cat Tien are a more dull olive green and lack these bold stripes. There are other differences, but in fact there are more similarities, whether in relation to the amber markings at the wing bases or the exact match in size. It will go to far to discuss all here, but suffices it to say that the species from Cat Tien is in the very least a different subspecies and possibly, and that would be truly amazing, a new species of Gynacantha, closely related to, but sufficiently different from, G. khasiaca. Currently we are trying to verify the exact details of the specimens used by Fraser and deposited in the British Museum. Below photos taken in December, of relatively fresh specimens, by James, and of last weekend, of old specimens, by myself. More details will follow when the time is right!

Scan of old male, very dark. Note dark amber wing bases and long epiproct.
Old male in lateral view, showing olive-green thorax and blueish pattern on S2. Eyes blue, not green as in Fraser's description

A fresher male in December, courtesy of James Holden. Note again the dark wing bases, the long appendages and epiproct and yellow frons with blackish T-spot.

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