Comparative osteology and intergeneric relationships of the tongue soles (Pisces; Pleuronectiformes; Cynoglossidae)

Abstract

This article contains the first detailed osteological study of several flatfish species belonging to the three currently recognized genera of tongue soles (Cynoglossidae). The resulting information was used to reassess, following the cladistics methodology, the monophyletic status of the family and to put forward a hypothesis of generic relationships. The polarity of the character states was determined by outgroup comparison using the Soleidae as the sister group of the Cynoglossidae and the Achiridae as the sister group of the soleid–cynoglossid lineage. An analysis of numerous characters corroborated the monophyletism of the Cynoglossidae. It was also found that the genus Symphurus (Symphurinae) is monophyletic and is the sister group of the monophyletic Cynoglossus–Parapaglusia (Cynoglossinae) lineage. Parapaglusia was shown to be monophyletic, but no evidence was found to corroborate a similar status for Cynoglossus. An examination of the osteology of more species belonging to the speciose genera Symphurus and Cynoglossus is needed to further test this hypothesis of relationships.