Monophyly and intrarelationships of the family Pleuronectidae (Pleuronectiformes), with a revised classification

A cladistic analysis of interrelationships for 53 (of 59) pleuronectid species was performed by using 106 morphological and osteological characters. The analysis resulted in 128 equally parsimonious cladograms (heuristic search, 403 steps, consistency index=0.33, retention index=0.79). A 50% majority-rule consensus cladogram indicated that only five of 47 resolved nodes were observed in less than 100% of the cladograms. These five nodes are restricted to interrelationships within one subfamily. The Pleuronectidae is monophyletic according to ten synapomorphies. In addition, five subfamilies were defined: Hippoglossinae, Eopsettinae, Lyopsettinae, Hippoglossoidinae, and Pleuronectinae. The largest subfamily, the Pleuronectinae, was further subdivided into four tribes: Psettichthyini, Isopsettini, Microstomini, and Pleuronectini. The interrelationships established within Pleuronectidae provide a strong foundation for a simplified yet phylogenetically informative taxonomic nomenclature at the genus-group level. The following genera are reclassified: Atherestes and Reinhardtius to Reinhardtius; Errex, Glyptocephalus, and Tanakius to Glyptocephalus; Embassichthys, and Microstomus to Microstomus; Hypsopsetta and Pleuronichthys to Pleuronichthys; and Kareius and Platichthy to Platichthys. To preserve the monophyletic status of Eopsetta, E. exilis was reassigned to the genus Lyopsetta (Lyopsettinae). The genus Pleuronectes was found to be polyphyletic. Monophyly of this genus is established by revising it to include only five species; Pleuronectes glacialis, P. pinnifasciatus, P. platessus, P. putnami, and P. quadrituberculatus. Other species, formerly placed in Pleuronectes, are now reclassified to Isopsetta, Limanda, Parophrys, Psettichthys, and Pseudopleuronectes. The monophyletic status of Limanda (six species) is uncertain because of unresolved relationships between these species and other taxa in the tribe Pleuronectini.