Developent of the larval and juvenile pharyngeal dentition in Myxocyprinus asiaticus and its systematic significance

Most species of the family Catostomidae are distrivuted in North America and so far only one species Myxocyprinus asiaticus has been reported in China. There is a necessity of studying the development of pharyngeal dentition of larval and juvenile in M. asiaticus as a research of the special subject.At the earliest stage of pharyngeal dentition in larval, catostomids and cyprinids are similar both in their external features and arrangments. Thereafter, they develop into two different ontogenetic type.In catostomids, it is more special that four rows of teeth coexist similtaneously, but among them only one row of functional teeth in the process of development is ankylosed at the pharyngeal bone. Mary plesiomorphies it has, such as the shape of whole pharyngeal teeth is similar to the ceratobranchials of the foour front gill arches and the ankylosed teeth preserve the original form of gill rakers etc. It is concluded, that the catostomids is more primitive in phylogeny of suborder Cyprinoidei.