With those straight spines seems to be "Neoplocaederus" pedestris (White, 1853), though the pronotal sculpture reminds of N. obesus (Gahan, 1890). I have got specimens of this latter species from Khon Kaen.
Concerning Plocaederus/Neoplocaederus, the genus Plocaederus should be restored as soon as possible as all authors previously considered.