MORPHOLOGY

External characteristics

Male
Forewing length (mm): 45-52. Wingspan (mm): 80-88.
Forewings: Upperside dark brown to black with small pale blue submarginal spots, with or without a large white spot over end of cell and adjacent region, with or without bluish sheen over much of the wing, sometimes paler in internervular areas; underside plain pale to dark brown with complete series of small white submarginal spots, sometimes some white median spots and a white patch in upper half of cell. Hindwings smooth or very slightly crenulate, with or without tiny submarginal spots, may have whitish area in space 1b and cell, which may extend to third of wing; underside plain pale to dark brown with complete series of small white submarginal spots, may have some white median spots and a large white patch from vein 1 to vein 7, crossed by dark veins.

Female Wingspan (mm):up to 93.
Slightly larger, upperside whitish submarginal spots absent to all present, whitish median spots absent to more or less expressed, sometimes extended to fill most of internervular spaces, whitish spot in cell near upper end present or absent, sometimes bluish sheen over apical half of wing; underside as male. Hindwing very slightly crenulate to smooth outline; upperside dark brown, spotless or, usually more or less arrow-like submarginal spots may be whitish in cell and internervular spaces; underside as male.

Subspecies and variation

Very much variation as outlined above. Part of the variation is geographical; seven subspecies have been recognized, six of which occur in the Malesian region. Most extreme are the subspecies from Nias, ssp. niasicus, of which the female can be spotless dark brown on the upperside and the male-like female form of the subspecies of Sumatra and W Malaysia, ssp. aenigma, with large white areas on forewing and hindwing and without bluish sheen on the forewing, while other females of the same subspecies do have a bluish sheen and no large white area, just whitish between the veins.

Similar species

_{source: Jan Moonen, peronal communication 2020}