The female FW has an interrupted yellow line, it seems to be the key character to differentiate them.
Yes, that is correct, the second spot from the apex of the discal band is missing both in this female and in the underside of the first specimen ever seen, which was photographed in nature. Presumably this is a constant but small difference, not obvious dimorphism but a difference between the sexes.
It will be interesting to see the upperside of the female after it has been spread, as the hindwing is half covered by the forewings in the photo above.
It certainly is amazing that this butterfly has not been found before, as Fiji has been very well explored in general over a very long time, and it's not exactly a large place. Seemingly it only occurs deep inside the forest on the Natewa Peninsula, and is not found anywhere else. Apparently the Japanese who went looking for it tried to find it in similar habitat on the main part of the island not far away for a couple of days but found absolutely nothing. They only saw it on the peninsula.