A new genus and species of percomorph fish, Pietschellus aenigmaticus gen. et sp. nov., is described from the Eocene (Ypresian) micritic limestone of the Monte Postale site of the Monte Bolca locality, northern Italy. This new percomorph taxon is based on a single well-preserved nearly complete specimen that exhibits a unique combination of features. A detailed comparative analysis indicates that Pietschellus possibly was a benthic fish which shares several character states with certain lophiiform, callionymoid, trachinoid, blennioid, pterygocephalid, cottoid and scorpaenoid taxa. Most of these shared character states, however, are reductive and seem to be related to the convergent benthic lifestyle and/or to the relative elongation of the body, being the product of parallel or convergent evolution. Therefore, the present evidence does not favour any sister-group relationship and, as a consequence, Pietschellus is placed as incertae sedis within the percomorph fishes. Copyright © 2010 John Wiley & Sons, Ltd.