P. ewingii = dagger shaped marking (i.e. joined) P. dyscrita = not joined or dagger shaped. Or as Peter Marriott says in Moths of Victoria Pt.9 CD pages " (P. dyscrita) .. can be distinguished from the similar P. ewingii by the well separated reniform and obicular spots..." Good to re-read this saying 'well separated' as some moths have me wondering.
Well separated in this specimen, so have included a copy in https://lepidoptera.butterflyhouse.com.au/hade/dyscrita.html Hope you approve? Thanks, Don.