Articulation of the pelvic spine in acanthopterygian fishes,with notes on its phylogenetic implications

The pelvic spine articulation in 88 non-squamipinne acanthopterygian species belonging to 59 families and 8 orders was examined. For most acanthopterygians, the pelvic bone lacks a foramen for the attachment of the pelvic spine flanges and this structural condition is considered a primitive acanthopterygian state. Only in Caproidae, Leiognathidae, and Polynemidae among the examined species do the pelvic spine flanges fuse through a foramen in the pelvic bone and this articulation is considered most derived. In the remaining acanthopterygians examined, the pelvic spine flanges butt against each other through the pelvic foramen. However, these flanges do not fuse. This structure is considered an intermediate state. The possible phylogenetic implication of these articulating states regarding acanthopterygian phylogeny is discussed.