MORPHOLOGY

External characteristics

Male
Forewing length (mm): 52-57. Wingspan (mm): 90-100.
Forewings: Upperside dark brown to black, indistinct paler double stripes between the veins; underside similar, but internervular stripes conspicuous. Hindwings crenulate, no tail; upperside black, with or without indistinct ochreous submarginal lunules in spaces 2 and 3, or these lunules grown into bigger spots in spaces 1b-4, hollowed outwardly, and in space 1b with some indistinct red; underside black, dark red patch in space 8 on both sides of the precostal vein, which is outlined in black, irregular ochreous spot in spaces 1b to 4, becoming bluish in space 4, extended to or close to outer margin along veins 2-5 and enclosing round black spots in spaces 1b to 4, vaguely defined blue submarginal lunules in spaces 5 to 7.

Female
Forewing length (mm): 60-62. Wingspan (mm):95-100.
Forewing, upperside brown with dark brown to black veins and internervular stripes (i.e. the double pale internervular stripes of the male so much extended as now virtually being the ground color), dark brown to black in basal half of spaces 1a to 3, basal quarter of cell may be ochreous white; underside as upperside. Hindwing, upperside dark brown to black, large whitish patch in outer half of wing from space 1b to 5, enclosing dark brown elongated spots in spaces 1b to 4; underside similar, amy have some indistinct bluish dots in spaces 6 and 7, dark red patch in space 8 on both sides of precostal vein, which is outlined in black.

Subspecies and variation

The species is restricted to Sumatra and geographic variation has not been reported. Individual variation as described above.

Similar species

Nearly as dark as P. acheron, but not easily mistaken, as the two species do not occur in the same region.

_{source: Jan Moonen, peronal communication 2020}