The Plain Tiger, also known as the African Monarch, is a medium-sized (wingspan of 7–8 cm) butterfly widespread in Asia and Africa.
The male Plain Tiger is smaller than the female, but more brightly coloured.
There are three subspecies:
1. Danaus chrysippus chrysippus (Asia, Mediterranean region, northern tropical Africa);
2. Danaus chrysippus alcippus (Cape Verde Islands through tropical Africa to Yemen and Oman). This subspecies is browner with broader white forewing spots;
3. Danaus chrysippus orientis (Saint Helena, southern tropical Africa to South Africa, Madagascar, Comoros, Seychelles and Mascarenes. This subspecies has small white forewing spots.

This is the subspecies Danaus chrysippus orientis. 

Dr. David Lees from the Department of Zoology of the University of Cambridge, United Kingdom, helped me identify 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.

1st photo: Andasibe-Mantadia National Park, Madagascar, 15 January 2014
Other photos: Mananara Lodge area, Anjozorobe, Madagascar, 17 January 2014