Anatomical revision of the Australian teleosts Cavenderichthys talbragarensis and Waldmanichthys koonwarri impacting on previous phylogenetic interpretations of teleostean relationships

Abstract

Bean, L. B. & Arratia, G., 4 October 2019. Anatomical revision of the Australian teleosts Cavenderichthys talbragarensis and Waldmanichthys koonwarri impacting on previous phylogenetic interpretations of teleostean relationships. Alcheringa 44, 121–159. ISSN 0311-5518. Australia has two important sites for Mesozoic fishes. The Talbragar Fossil Fish Bed in New South Wales is a Tithonian freshwater lake deposit containing the iconic form Cavenderichthys talbragarensis, first described in 1895. The Koonwarra Fossil Bed in Victoria is an Albian freshwater lake deposit containing Waldmanichthys koonwarri, first described in 1971. Following the tradition of the time, both species were first ascribed to the historic genus Leptolepis. In 2015, these two species were placed into a newly erected family, Luisiellidae, with the Oxfordian–Tithonian fish Luisiella feruglioi from the Cañadón Calcáreo Formation in Chubut, Argentinian Patagonia. This new family was interpreted as a stem teleost group, closer to Leptolepis coryphaenoides than to the crown-group Teleostei, a contrary hypothesis to previous interpretations that placed Cavenderichthys as a teleost incertae sedis in the crown Teleostei. This paper re-examines the morphological characters of the Australian taxa, including 46 previously undescribed specimens of W. koonwarri, from Museum Victoria. Some of the new characters include the special configuration of the jaws and the position of the quadrate-mandibular articulation; the special vertebral pattern at the level of the abdominal/caudal regions; a stegural-like uroneural in the caudal skeleton; and the structure of the scales. Finding the new characters in Waldmanichthys called for reappraisals of the morphology of Cavenderichthys and Luisiella. In the case of Cavenderichthys, 34 specimens were re-examined, but for specimens of Luisiella, a conservative approach was followed, based on its last morphological description as well as photographs taken more recently. The systematic position of the three Gondwanan taxa was re-evaluated using a pre-existing data matrix including 240 characters and 56 taxa. The new results give a very different scenario, with the three taxa now included in the crown-group Teleostei. The family Luisiellidae is restricted to its type species L. feruglioi. The two Australian fish genera cluster together with the Late Jurassic European genera Leptolepides and Orthogonikleithrus and are now ascribed to the family Orthogonikleithridae. The new results suggest that the three Gondwanan genera are stem taxa to the Osteoglossocephala (osteoglosomorphs plus more advanced teleosts), and their combination of morphological characters has a major effect on the interpretation of basal euteleosts, questioning some previous interpretations, as for instance, the homology of the stegural as an euteleostean character. Lynne B. Bean* [lynne.bean@anu.edu.au], Research School of Earth Sciences, Australian National University, Acton 2001, Australia; Gloria Arratia [garratia@ku.edu], Department of Ecology and Evolutionary Biology and Biodiversity Institute, University of Kansas, Dyche Hall, Lawrence, KS 66045, USA.