I shot the following Arctornis at bukit batok today. It has a discal spot, but the antenna,palps and frons are quite well hidden. I cant really decide if it has corrgated marks base on your comments, but i think its Arctornis riguata. I would like to hear your inputs.
This mating pair have wing fringes narrowly brownish and their legs seems to be faintly spotted, which is why i ID it as such, but i would like to hear your opinion on this observation