Loancorhynchus catrillancaigen. et sp. nov., a new swordfish (Xiphioidei, Blochiidae) from the Middle Eocene of central Chile

Abstract

This contribution describes the skull remains of a swordfish (Perciformes, Xiphioidei), recovered from Middle Eocene beds of central Chile. Comparison with known fossil and extant xiphioids reveals derived traits only present in the Neogene swordfishXiphias gladius(Xiphiidae, Xiphiinae), these being a elongated rostrum composed of premaxillaries and possible prenasals, a dorsoventrally high and slender hyomandibular-metapterygoid complex, and a rounded, convex operculum. Also, strong ridges and sulci are present in the dorsal part of the rostrum, a feature only present in the billfish generaAglyptorhynchusandXiphiorhynchus, and in the swordfish genusBlochius. In addition, the specimen also has villiform teeth in the rostrum and lower jaw, a feature previously documented only in the Paleocene genusHemingwaya. Such a unique combination of characters in the specimen allows classifying it as a new genus and species,Loancorhynchus catrillancai. Phylogenetic analyses obtainedXiphiorhynchusoutside the Xiphiidae, suggesting instead narrow relationships to the Paleocene-Eocene generaHemingwaya+Palaeorhynchus+Homorhynchus. Loancorhynchusis obtained as an intermediate form betweenXiphiasandBlochius.The specimen represents the first Paleogene swordfish described in the southeastern Pacific.