Sunday, 5 June 2016

Nychogomphus lui, a Hanoi specialty

In 2011 Sebastien Delonglee already published photos of several enigmatic gomphid species that occur in the Hanoi region. Eventually one of these could be identified. It was Nychogomphus lui, described by Zhou, Zhou and Lu in 2005.

Apparently this species inhabits large slow rivers and the Red River is perfect for it. But it is a bit like Gomphus flavipes in Europe, another inhabitant of large rivers. That species too is best found by looking for exuviae of freshly emerged specimens. Nychogomphus lui emerges at the end of May and in early June. Sebastien has seen them for instance from a window perched in a tree! But how to reliably find them? In other years I could not. But this spring we discussed the area along the Red River where the Anax indicus appeared. It had some open forest areas close to the river. Might this be a good place?

Sebastien recently texted me to say he had seen a female. Soon after he found two more, on different days, all fresh. So today I went to the area, sweating it out (37 degrees in the shade). And found Nychogomphus lui, both a male and a female, perched in the shade close to the ground. Both were fresh. So this is the way to find them! Maybe they visit the river at dusk when mature, as other species of Nychogomphus do. Or maybe they mate elsewhere and the males do not return. We hope to find out.

For now this is the only place in Vietnam where the species has been found, but it may be more widespread. Generally we avoid the large rivers of Vietnam when we look for Odes, so it may be overlooked.

The female as I first found it, perched on a leaf. The color of the eyes shows she is very young, as is also evidenced by the shine of the wings.
She has amber wing bases. The wind was bothering her, so after this shot she took off

But when I turned around there was this wonderful fresh male! He had appeared while I was taking pictures of the female. Note the waved inferiors and black tipped superiors.

The same male in dorsal view