Taxonomic revision of the Poecilopsettidae and phylogenetic analysis of the Rhombosoleidae and Pleuronectiformes (Acanthopterygii)

The family Poecilopsettidae (Pleuronectiformes) occurs in the Pacific, Indian and Atlantic oceans. A taxonomic revision of all 19 species considered valid up to now was completed. Type specimens and additional material known for all these valid species were examined and measured. One new species is described (Poecilopsetta dorsialta), two species are synonyms of previously described species: Nematops chui is a junior synonym of N. macrochirus and Poecilopsetta megalepis is a junior synonym of P. plinthus. There are now 18 valid species in the family: two in the genus Marleyella, three in the genus Nematops and 13 in the genus Poecilopsetta. The genera Nematops and Marleyella are monophyletic. However, the monophyly of the genus Poecilopsetta remains doubtful because of the absence of unique characters for all 13 species of the genus.; The family Rhombosoleidae (Pleuronectiformes) (sensu Norman, 1934) is a group of 19 species distributed in Southern Australia, New Zealand, in the Indo-Pacific Ocean off Western Australia and South America. A data matrix of 87 morphological characters was analysed using cladistic methodology to assess the monophyly of the Rhombosoleidae and to determine the interrelationships within this family. Achiropsettidae and Poecilopsettidae were used as outgroups. The results (16 equally parsimonious trees; 118 steps; CI = 0.669) found the family Rhombosoleidae to be monophyletic on the basis of eight apomorphies. The Rhombosoleidae was not monophyletic with the genera Azygopus, Oncopterus and Psammodiscus and they were removed from the family and added to a data matrix of of pleuronectiform families to assess their relationship within the order. Azygopus is placed in the Achiropsettidae. Psammodiscus and Oncopterus form a trichotomy with a large clade formed by Rhombosoleidae, Poecilopsettidae, Achiropsettidae, Samaridae, Achiridae, Soleidae and Cynoglossidae (6 equally parsimonious trees; 109 steps; CI = 0.477). The family Paralichthodidae (sensu Cooper and Chapleau, 1998a) is the sister-group of a large clade formed by the families exhibiting a bothoid type of caudal skeleton (Scophthalmidae, Bothidae, Paralichthyidae and Pleuronectidae) and by clade III (Psammodiscus, Oncopterus, Poecilopsettidae, Rhombosoleidae, Achiropsettidae, Samaridae, Achiridae, Soleidae and Cynoglossidae).