Pupa puzzle

I've got moth books and caterpillar books, but need a pupa book! This empty pupal skin was underneath some Sycamore bark today. I did wonder if it could be the Regal Piercer, Pammene regiana, which is known to pupate in Sycamore bark. However, my pupa doesn't match other images of regiana.

I'm not expecting that this can be fully identified, but if anyone can narrow it down that would be very impressive. The hooks on the cremaster are also impressive!

Pupa from under bark

Close-up showing cremaster