Thursday, 21 April 2016

Tramea basilaris - a true vagrant

Today I was hoping to quickly sneak off to the little pool where the last few days the Anax indicus had been hanging around, but it was cloudy all day. Just after lunch the sun seemed to start peeking through the clouds, so I made a dash for it. The pool is only 15 minutes from my place of work. But when I got there the sun was gone again and clouds ruled the sky. But at the side of the pool there was a large branch lying in the water and on one of the tips was a Tramea. It would be out of season for Trames virginia, but it did have rather large saddlebags. However, when I gave it a closer look the lack of an obviously protruding hamule and a hole in the saddlebag soon made it clear this was something else. Indeed, Tramea basilaris. This is an extraordinary species, originating in Africa individuals roam as far as Japan and South America. In Vietnam it is known as a vagrant. At least, that is what the IUCN website says. I had never seen it. So there you have it. At the small pool where a few days ago Anax indicus was discovered as a new species for Vietnam, today yet another rare long distance migrant. The winds have definitely shifted to summer patterns, blowing from the southwest.

Tramea basilaris, showing the genital lobe without a longer hamule.
From behind, showing the irregular saddlebags with paler "hole"

And another side view, showing the saddlebag pattern again.

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