DEVELOPMENT OF THE ANTERIOR VERTEBRAE IN THE CYPRINIDAE AND THEIR SIGNIFICANCE IN THE PHYLOGENSIS

The anterior vertebrae of nine species cyprinid juveniles,including Carassius cuvier,Cirrhinus molitorella,Coreius sp.,Erythrcoulter sp.,Labeo lohita,Magalobrama terminalis,Pseudorasbora parva,Puntius gonionotus,Rhodeus sp.,and one species catostomid juveniles Myxocyprinus asiaticus have been studied.They are similar in structure to those in the juvenile of the characin,Brycon,but exhibit two ossification centers above the anterior vertebrae.The anterior center,which represents the second supraneural,forms a plate-like bone and the second one,which may be in connection with the third and fourth supraneural,becomes the webrian complex. In the early juvenile stage of cyprinids,a bony spine appears on the upper anterior margin of the second ossification center.Two types of weberian complex growth can be recognized based on different developmental patterns of the bony spine.In Tribe Leuciscini species,the front and posterior bony spine both exist in the juvenile and enlarge themselves into the main part of the weberian complex,but in Tribe Barbini species the bony spine are weakly developed and a dorsal ridge processes from the second ossification center expands in front and behind the bony spine,forming a thin plate structure,which is the main part of the weberian complex. In agreement with the weberian complex development,the second and third vertebrae are seperated in most juveniles of Tribe Leuciscini.On the other hand,the second and third vertebrae are invariably fused in all juveniles of Tribe Barbini,representing a more derived condition.These two features of juvenile cyprinids provide clearer information on phylogenesis than the features of the adults.