I've got a specimen closed to yours, coming too from Laos, (Hua Phan). I called it Pseudanaesthetis nigripennis Breuning, 1940. If somebody can help us ...
It seems to me the most logical thing. When I saw it for the first time, I though Anaesthetis but I had no time to check the correct ID. Differently form this genus, Pseudanaesthetis has a short lateral tooth at each side of the prothorax.