MORPHOLOGY

External characteristics

Male
Forewing length (mm): 52-65. Wingspan (mm): 94-112.
Forewings: Upperside black, very slightly paler between the veins; underside black with veins of cell finely outlined in gray and double violet-grayish stripes between the veins. Hindwings crenulate with strong spatulate tail at end of vein 4; upperside black with large white or pale yellowish mark from front margin to vein 5 (rarely just crossing it) consisting of three spots (in spaces 5-7), the upper one the narrowest, less that half width the spot below it; underside same pale mark, but in addition there are submarginal red lunules, larger red spots in spaces 1b and 2, with some blue scales in the red and more or less enclosing a black 'eye'.

Female
Forewing length (mm): 58-69. Wingspan (mm):93-122.
Similar to male but on underside forewing pale outlining of veins of cell and double stripes between the veins more strongly developed.

Subspecies and variation

The variation in size and expression of the markings is largely geographical; eleven subspecies have been distinguished, seven of which occur in the Malesian region.

Similar species

The only species with which P. helenus could be confused in its distribution area are P. iswara and P. iswaroides. Both lack the red submarginal spots on the underside of the hindwing, except the ones at tornus.

_{source: Jan Moonen, peronal communication 2020}