Adelpha fessonia, the band-celled sister or Mexican sister, is a species of butterfly of the family Nymphalidae.

It is found in Panama north through Central America to Mexico.

It is a periodic resident in the lower Rio Grande Valley, Texas.

Larvae in Texas and northeastern Mexico feed on Celtis lindheimeri.

Adults feed on nectar from flowers such as Cordia, Croton, and Baccharis.