@TimL : hope you have her in protective custody to lay some eggs you could rear to get a male ? Could you get a leg to BOLD to get DNA to classify it ?
The available photos of female Pterolocera show much smaller vestigial wings than this specimen has. Looking at the flightless females in the various families in https://lepidoptera.butterflyhouse.com.au/faqs/flightless.html I see no matches there, so I wonder if this one of the two unillustrated families there : Hepialidae and Zygaenidae. This specimen is perhaps too big for Zygaenidae, so I suggest Hepialidae.
Possibly a female Pterolocera but I've found very few images to compare it with eg.: https://bie.ala.org.a/species/https://biodiversity.org.au/afd/taxa/b98fc741-0a0c-425e-84c0-1a43df0bba2c#gallery
