This moth was observed at a cold, remote Silver Fir Forest, uninhabited place except by some government staffs looking after the Brown Trout Hatchery Centre nearby a stream which feeds a lake of about 3 km in circumference.
Looking at the antennae this is a Female. The photo of the Male is uploaded in the subsequent post.
WS: 54 mm
Variations of colour, shade, and distributions of spots, besides their body sizes - which of course could be due to their life stages - is simply mindboggling, and quite confusing (at least for me). Unless one is thoroughly experienced in dealing with this species this Beetle seems to be a huge challenge to ID.