Ceylon tiger  (Parantica taprobana)

Sri Lankan Insects (March 2004)
http://www.srilankaninsects.net/Butterflies/Danaidae/CeylonTiger/CeylonTiger.htm

Michael and Nancy van der Poorten in Gehan' s Guide to the Birds, Butterflies and Dragonflies of Sri Lanka by Gehan de Silva Wijeyeratne.
http://www.jetwingeco.com