MORPHOLOGY
External characteristics
Male
Forewing length (mm): 42-60. Wingspan (mm): 78-104.
Forewings: Upperside black, with or without macular band of separate narrow white spots from outer margin in space 4 to 2/3 of costa, tiny white spot at margin in space 8; underside similar, but may have a pale violet submarginal spot in space 1a-b. Hindwings crenulate, with strong spatulate tail at end of vein 4; upperside black with large creamy to pale yellow central area consisting of spots in space 3 to 7, spots much longer than wide, except the uppermost one; underside similar, but the pale area may be extended to the inner margin by smaller violet spots and there may be violet markings in spaces 4, 5 and 7.
Female
Forewing length (mm): 47-67. Wingspan (mm):93-111.
Forewing as in male but always with the macular band, which may have a pale ochreous flush, and there may also be a pale ochreous whitish double spot at hind margin. Hindwing as in male, pale yellow patch more or less extended to inner margin.
Subspecies and variation
The species varies considerably over its large distribution area from N India to Taiwan and throughout Sundaland and 11 subspecies have been distinguished six of which occur in the Malesian area. The variation is in size (the smallest subspecies is ssp. nephelus from Java), the presence or absence of spots and the intensity of the colors.
Similar species
Unmistakable.
source: Jan Moonen, peronal communication 2020