Junonia rhadama, sometimes also called the Brilliant Blue, is a butterfly found on Madagascar, Mauritius, Rodrigues, Réunion, the Comoros, and the Seychelles.
This is a female.

Dr. David Lees from the Department of Zoology of the University of Cambridge, United Kingdom, has help me identifying this butterfly.
David Lees has extensive field research experience in Madagascar and is considered the authority on Madagascar butterflies.
I was very fortunate to meet him in Madagascar in January 2014 at the time I was visiting.

Mananara Lodge area, Anjozorobe, Madagascar, 18 January 2014