Specimens of Mendosoma lineatum recovered from the stomach contents of rockhopper penguins (Eudyptes chrysocome) and snoek (Thyrsites atun) at Gough Island represent the first record of this species in the Atlantic Ocean. In view of similar descriptions in the literature, fishes of the genus Mendosoma from the Pacific and Indian oceans were compared with the specimens from Gough Island in order to re-evaluate the taxonomic status of the three nominal species, M. lineatum Guichenot, 1848, M. elongatum Kner, 1864 and M. allporti Johnston, 1881. All the specimens used in this study were found to belong to one species. Comments on the current knowledge of the biology of M. lineatum are given as well as remarks on two other species of this genus described by Guichenot, 1848.