Larval vs. Adult Pharyngeal Dentition in Some Japanese Cyprinid Fishes

Abstract

The development of the pharyngeal dentition was examined in 13 species of five subfamilies of the family Cyprinidae. A previously described difference between the larval and adult dentition in Gnathopogon caemlescens was observed in 11 species of Gobioinae, Cyprininae, Leuciscinae, and Danioinae, but was not seen in two species of Acheilognathinae. The adult dentition is usually complete by the later larval or juvenile period. In the adult dentition, the functioning teeth are generally shed at each position, when the replacement tooth has been ankylosed to the bone, or when the germ of that tooth has grown sufficiently. In the larval dentition, however, the replacement tooth is ankylosed medial to the functioning tooth, so the older functioning tooth is retained after ankylosis of the replacement tooth. That is why the dentigerous surface of the bone grows rapidly during the larval period. Each tooth row represents a single replacement wave. The distribution and pattern of the central teeth are exactly the same in all types of the larval dentition. However, those of the anterior teeth vary between and within different species. The larval dentition develops into the major row of the adult dentition through tooth replacements. The number of tooth families in the larval dentition is completely consistent with the tooth number of the major row in the adult dentition. Therefore, the number of major row teeth owes its variation to that in the appearance pattern of the anterior teeth.