Resolving the taxomony of “Tharrias” feruglioi, a Late Jurassic basal teleost (Actinopterygii) from Patagonia

SFERCO, E.

San Juan

Congreso; IV Congreso Latinoamericano de Paleontología de Vertebrados; 2011

Instituto y Museo de Ciencias Naturales, Facultad de Ciencias Exactas, Físicas y Naturales

The Late Jurassic basal teleost “Tharrias” feruglioi Bordas, 1942, is very well represented in the Cañadón Calcáreo Formation in central Chubut, Argentina by dozens of juveniles and adult specimens. The species has been erroneously assigned to Tharrias (the original publication included a misspelling of the name), a genus erected for Tharrhias araripes Jordan and Branner, 1908, a gonorynchiform from the Cretaceous Santana Formation of Brazil. “T”. feruglioi is certainly not a gonorynchiform because of the lack of: reduced parietal bones; a first neural arch especially enlarged, contacting the occipital margin with an extensive, tight joint, and epicentral bones (Wiley and Johnson, 2010). Besides, the proposition held by Bocchino (1978), that “T”. feruglioi should be placed in the genus Leptolepis, is also rejected here. Unlike Leptolepis (sensu Nybelin, 1974) “T”. feruglioi lacks a suborbital and a second supraorbital bones. Referral to the family Leptolepidae sensu stricto is here also denied as well. Recently, Arratia and Hikuroa (2010) proposed three uniquely derived characters that support this family: vertebrae with thin and smooth autocentra, autocentra and chordacentra not constricting the notochord, and lack of cavities for adipose tissue in the walls of the autocentra. In contrast, “T”. feruglioi has vertebrae with thick, sculptured autocentra that strongly constrict the notochord. In addition, Luisiella inexcutata Bocchino, 1967, the other teleostean taxon described for the Cañadón Calcáreo Formation, is considered here a junior synonym of “T”. feruglioi. Consequetly, “T”. feruglioi should be moved to the genus Luisiella as Luisiella feruglioi nov. comb. and, pending a comprehensive cladistics analysis, it should remain as Teleostei incertae sedis.