MORPHOLOGY
External characteristics
Male
Forewing length (mm): 52-58. Wingspan (mm): 73-81.
Forewings: Upperside dark gray/black, complete band of median spots from hind margin to near apex, lower spots large, but all separate, no other spots; underside similar, but ground color rather paler, may have a violet flush Hindwings Crenulate, tail at end of vein 4; upperside outer third to half dark grayish, not sharply defined, basal third to half yellowish to pale violet-gray, no spots; underside ground color as underside forewing, no spots, but an indistinct pale area under middle of costa that may extend to middle of wing.
Female
Similar to male.
Subspecies and variation
Strong variation in the width of the median spots on the forewing and the extension of pale areas on the hindwing; 14 subspecies are recognized, eight of which are found in the Malaysian area.
Similar species
The only species that comes rather close is G. empedovana, which has a brown ground color and lacks the conspicuous median spots in spaces 1a and 1b on the forewing.
source: Jan Moonen, peronal communication 2020