The eastern Pacific black ghost shark, Hydrolagus melanophasma is reported from deep waters off Chile and is described from specimens collected off Valdivia at depths of 1150 to 1720 m. This species is distinguished from all other members of the genus by its large, curved dorsal fin spine, which extends beyond the dorsal fin apex; a second dorsal fin of uniform height along the caudal peduncle; large pectoral fins extending beyond the pelvic fin insertion; and a uniform black color of the body. Catch records of this species in Chile suggest a discontinuous distribution along the continental slope of the eastern Pacific Ocean, restricted to the Middle America and Atacama trenches. These observations elevate the number of chimaeroid fishes inhabiting Chile to five species.