Saving the image & zooming in shows the shape of the male brand is much as in T. besta
That & the strongly developed triangle orange patch at the base of space 2 is consistent with T. besta.

Compare.
https://singapore.biodiversity.onlin...doptera-000056


In contrast T. bambusae bambusae, the subpecies lightly to be found here have a narrow slightkly different brand& the base of space not solidly orange.
Typical T. bambusae bambusae from Assam.
https://c1.staticflickr.com/5/4017/4...698_z.jpg?zz=1


It is thus a small size T. besta.


TL Seow: Cheers.