MORPHOLOGY
External characteristics
Male
Forewing length (mm): 70-95. Wingspan (mm): 86-104.
Forewings: Upperside forewing blackish brown, broadly whitish or yellowish along the veins, giving a striped appearance, basal area solid dark, running through middle of cell and reaching hind margin before middle; underside forewing similar. Hindwings Upperside hindwing blackish brown with a vague or clear yellow(ish) or creamish band from hind margin to front margin and very vague large submarginal spots; basal area dark brown, outer margin running from middle of front margin to middle of inner margin in an almost straight line; underside hindwing as upperside but yellow band and submarginal spots much clearer than on upperside, latter either yellow or red.
Female
Forewing length (mm): 59-64. Wingspan (mm):96-105.
Larger than male, but further similar.
Subspecies and variation
Based on variation in extent, intensity and tinge of the wing markings four subspecies have been distinguished.
Similar species
Easily recognizable by the creamisch pale band on the hindwing that runs from hind margin to front margin and the almost straight inner edge of this band.
source: Jan Moonen, peronal communication 2020