G. stigmatipennis (White, 1855) is the only Gnatholea recorded from the Philippines. G. subnuda Lacordaire, 1869 (from Borneo) looks similar. I have one of these from the Philippines, too.
At first that is what I thought this was but since I saw it, I have seen two others from the Philippines that look similar to the species that occurs in Vietnam. I will try and post a picture of it to see what you think.
I agree: it is not G. stigmatipennis, evidently. It rather seems G. subnuda Lacordaire, 1869, which you can find in the Web misidentified as G. eburifera.