@donhe I did collect this caterpillar and I have added two very poor photos of it taken on 27 Sept (it was very camera-shy). I fed it on some Clematis leptophylla, the only other Ranunculaceae in the area, and later on some Wahlenbergia. It wasn't clear when it stopped feeding, but on 1 November I found not a moth, but a parasitic wasp! I have made a separate sighting for that (sighting 4625468).