Basal teleosts and the question of elopomorph monophyly. Morphological andmolecular approaches

The methodology used by previous authors to resolve the relationships of th e elopomorphan taxa is criticized. The morphological characters that have b een proposed to support the monophyly of the Elopomorpha are reviewed and i t is shown that most oi them are weak. A new hypothesis of relationships is proposed on the basis of nucleotidic sequences oi ribosomal RNA 185, 16S a nd 12S. In order to really test all the possible relationships, the monophy ly of the Elopomorpha was not considered a priori. The tree was rooted on A mia calva and Lepisosteus osseus and the ingroup taxa sampling was subseque ntly increased. The obtained topology shows that the Elopomorpha is a non-m onophyletic taxon. Elopiforms, anguilliforms, albuliforms and notacanthifor ms are considered here as four monophyletic, incertae sedis taxa among basa l teleosts. (C) 2001 Academie des sciences/Editions scientifiques et medica lies Elsevier SAS.