New description of Brachyichthys manselii (Egerton, 1872) comb. nov. (Neopterygii: Halecomorphi) from the Upper Jurassic of Kimmeridge, England

The osteology and the systematic position of Brachyichthys manselii comb. nov., a fossil fish first mentioned by Egerton in 1872 as Semionotus manselii from the marine Upper Jurassic (Kimmeridge Clay) of southern England, are studied in detail. New findings from the Etches Collection make it possible to provide the first description of a complete specimen of this taxon and to assign this taxon to the genus Brachyichthys. The characters of the skull, the general morphology, some features of the caudal fin, and the dentition clearly refer this fish to the order Ophiopsiformes within the Halecomorphi. The similarity of many characters of this taxon to Brachyichthys typicus, the type species of the genus Brachyichthys from the Upper Jurassic of Solnhofen, convinced us that both belong to the same genus. Brachyichthys manselii is mainly characterized by the following unique combination of morphological characters: 50–60 small teeth on the maxilla; praeoperculum in the dorsal half largely covered by suborbitals; 18 segmented dorsal fin rays; broad caudal fin with 28 principal caudal fin rays; ∼45 vertical scale rows; at least one lateral line ossicle between the caudal fin rays; and lateral line curving upwards into the dorsal lobe of the caudal fin.