Pseudonacaduba aethiops, the Dark Line Blue or Dark African Line Blue, is a butterfly in the Lycaenidae family. It is found in Nigeria (east and the Cross River loop), Cameroon, Equatorial Guinea, Gabon, northern Angola, the Democratic Republic of Congo, Uganda, western Kenya, western Tanzania and Zambia. The habitat consists of forests. Adult males visit damp patches to drink. The larvae feed on Mundulea species.