Mynes geoffroyi, Nymphalidae. I believe this is a female based on slight differences in the underside markings.

This is the first time I've seen this species in my garden.
I planted the nymph's caterpillar food plant several months ago. Coincidence?
The butterfly showed no obvious interest in the food plant, landing about 8 m away and remaining there for about 20 minutes.
I checked the food plant afterward for the distinctive batches of eggs of the butterfly, and found none.