Bulletin of the Mizunami Fossil Museum

Bulletin of the Mizunami Fossil Museum No. 3

Comparative morphology of Cyprinid fishes, the Subfamily Xenocypridinae, with a comment to the systematic position of the fossil pharyngeal bones collected from the Miocene Mizunami group

Yoshio Tomoda

Published: 1976/12/25 　 Page: 157–162, pls. 37–42

Xenocypridinae, consisted of four genera and ten species, is a group of freshwater fishes endemic to the continental East Asia, Formosa and Heinan Islands.

This subfamily was, however, once the most flourished group of fishes at the Miocene lakes of Japan. The next appearance of this subfamily was recognized from the Pliocene lakes in China. These facts inevitably lead necessity of the further historical study of this subfamily to clear the East Asiatic geohistory. In this direction, osteological study of the recent forms should be the first task for the discrimination of the fossil specimens, however, such a work seems not to have come out until the present.

In the present paper the author gives the result of the gross morphological study of the four Chinese species each of which represents the existing genus respectively.

Morphological differences in the pharyngeals, their teeth and the number of tooth series between the recent genera were already rccognized by Chu (1935). Based on these differences, Chu proposed a model of evolutional direction in such a series: (Xenocypris, Plagiognathops)→Distoechodon→Acanthobrama  . A parallel trend is recognized in the number of gill rakers of these genera.

From the scrutiny of the feeding organs, however, a different interrelationship becomes possible between the recent genera. Moreover, fragmental knowledges obtained from the study of the fossil specimens suggest the existence of extinct genera, which were provided with characters of both Cultrinae and Xenocypridinae.