The semionotid Lepidotes piauhyensis Roxo and Löfgren, 1936, is redescribed on the basis of original and new material obtained from the Pastos Bons Formation, ?Upper Jurassic–Lower Cretaceous of the Parnaíba Basin, in northeastern Brazil. The species is a hump-backed semionotid reaching about 480 mm standard length. It exhibits, among other characters: dermal bones of the skull roof and circumorbital series densely ornamented with tubercles, suborbitals disposed in a single row, moderately developed crushing dentition, a bony lamina on the ventral portion of the anterior ceratohyal, a complete dorsal scale row, and smooth ganoid scales of lepisosteoid type. The analysis of well preserved specimens allows the description of anatomical structures previously unknown for the species, particularly of the hyoid arch and suspensorium. Some of these structures are comparable to those of the Jurassic species Lepidotes gloriae Thies, 1989 (Cuba), Lepidotes elvensis (Blainville, 1818) (Europe), and Lepidotes lennieri Sauvage, 1893 (Europe).