Anatomical description and taxonomy of † Luisiella feruglioi (Bordas), new combination, a freshwater teleost (Actinopterygii, Teleostei) from the Upper Jurassic of Patagonia

Abstract

The teleosts of the Late Jurassic Almada Fauna (Cañadón Calcáreo Formation) from Patagonia have been known for decades, but their taxonomic assignment has remained problematic. Two teleost species were thought to be represented in these lacustrine deposits: †Tharrhias feruglioi and †Luisiella inexcutata. In recent years, numerous complete and excellently preserved specimens have been collected, justifying revision of all available material. After a detailed anatomical study, we conclude that only one species of teleost is present in this fauna. †Tharrhias feruglioi and †L. inexcutata are synonyms and represent a single species, and due to the erroneous referral to the genus †Tharrhias, which designates a different fish, the new combination †Luisiella feruglioi is proposed. This study has revealed great morphological variability, which can be explained as intraspecific variability (ontogenetic and individual) as discussed herein. The overall morphology of †L. feruglioi resembles that of basal teleosts. In particular, †L. feruglioi is intriguingly similar to †Cavenderichthys talbragarensis from the continental Late Jurassic Talbragar Beds in Australia, owing to the presence of features not commonly found in known basal teleosts (hyomandibular bone with preopercular process, lower jaw with deep coronoid process and lacking a leptolepid notch in the dentary, and first uroneural anteriorly reaching the second preural centrum) and probably derived features such as a preopercular canal with few simple tubules. The resemblance between the Almada and Talbragar faunas has been recently proposed in reference to the coccolepidid species present in both Gondwanan faunas and is here discussed regarding the anatomical similarities shown by teleosts.