A redescription of Omiodon cabassii Bassani 1888, a putative chlorophthalmoid fish (Teleostei: Aulopiformes) from the lower Eocene of northeastern Italy

Omiodon cabassii Bassani, 1888 is a poorly known teleost originally described in the late nineteenth century based on a single articulated specimen recovered from Eocene deposits of the Friuli-Venezia Giulia region (northeastern Italy). Despite its marine paleoenvironmental context, the specimen was initially assigned to Characi- formes by Francesco Bassani and later referred to the Myctophidae. Owing to the out- dated nature of the original anatomical description and the problematic taxonomic placement of the species, we conducted a comprehensive re-examination of the type specimen long-considered lost together with a stratigraphic reassessment based on micropaleontological analysis of the enclosing matrix of the fossil. New anatomical evi- dence supports assignment of this taxon to Aulopiformes, and we tentatively interpret it as a member of Chlorophthalmoidei. However, the poor preservation of the specimen precludes a more precise determination of its phylogenetic position within Chloroph- thalmoidei. Notwithstanding these limitations, Omiodon cabassii represents the oldest possible fossil record of this clade