A study of the holotype of Nothogaster paradoxa Lacordaire 1866 revealed that it consists of parts of two different insects glued together. The anterior part (head and thorax) belongs to Orphanobrentus curvirostris Chevrolat 1839 (Coleoptera, Brentidae) whilst the posterior part (abdomen without legs and genitalia) belongs to Figulus anthracinus Klug 1833 (Coleoptera, Lucanidae). According to the International Code of Zoological Nomenclature, the anterior part is considered herein as the holotype and the posterior part is excluded as extraneous. Consequently, Nothogaster Lacordaire 1866 becomes the senior objective synonym of Orphanobrentus Damoiseau 1962 new synonymy and Orphanobrentus curvirostris Chevrolat 1839 the senior subjective synonym of Nothogaster paradoxa Lacordaire 1866 new synonymy.
The following new combinations are also established: Nothogaster curvirostris (Chevrolat 1839); N. emarginata (Chevrolat 1839); N. laevicollis (J. Thomson 1858); N. picipes (Olivier 1807); N. punctatissima (Kleine 1920); and N. suturalis (Quentin 1966).