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

Abstract

A cladistic analysis of interrelationships for 53 (of 58) pleuronectid (Order Pleuronectiformes) species was performed using 106 morphologial and osteological characters. The analysis resulted in a 50% majority-rule consensus tree of 128 equally parsimonious cladograms (heuristic search, 403 steps, ci = 0.33, ri = 0.79). 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 (sensu Chapleau and Keast, 1988) are monophyletic based on ten synapomorphies. In addition, five subfamilies were defined Hippoglossinae, Eopsettinae, Lyonsettinae, Hippoglossoidinae and Pleuronectinae. The largest subfamily, the Pleuronectinae, was further subdivided into four tribes. Psettichyini, Isopsettini, Microstomini and Pleuronectini. The interrelationships established within Pleuronectidae provide a strong foundation for a simplified yet phylogenetically informative taxonomic nomenclature. The genera Atherestes and Reinhardtius; Embassichthys, Errex, Glyptocephalus, Tanakius and Microstomus; Hypsopsetta and Pleuronichthys are regrouped in Reinhardtus; Microstomus and Pleuronichthys, respectively. To preserve the monophyletic status of Eopsetta, E. exilis was reassigned to the genus Lyopsetta (Lyopsettinae). The genus Pleuronectes (as defined by Sakamoto, 1984a) is polyphyletic. It now includes only five species: Pleuronectes glacialis, P. pinnifasciatus, P. platessa, P. putnami and P. quadrituberculatus. Other Pleuronectes species are reclassified in Isopsetta, Limanda, Parophrys, Platichthys, Psettichys, and Pseudopleuronectes. The monophyletic status of the genus Limanda (six species) is uncertain based on unresolved relationships between these species and other taxa in the tribe Pleuronectini.