Observation on the Development of the Scutes in A Ten-Spined Stickleback, Musashi Tomiyo, Pungitius sp..

Abstract

The present report is one of the series of biological studies on the scutes of stickleback carried out by the author for six years from 1952 to 1968. The samples used are Musashi-tomiyo, Pungitius sp., collected in the suburbs of Kumagai, Saitama Prefecture, The results obtained are as follows:
1) In Musashi-tomiyo, it seems that the fifth (No. 5) scute appears first in the posterior region of the side of caudal peduncle. And then the other five or six scutes are formed in turn before and behind the fifth one. The arrangement of scutes shows the Semiloricata type.
2) The construction of scutes of Musashi-tomiyo: there appears no rhombic scute as seen in Pungitius sinensis, but rectangular scutes on the postero-tateral region of caudal peduncle. The main-axial ridges and lateral network ridges of scutes develop well, and the process progresses more steadily than that of Pungitius pungitius.
3) From these facts it may be concluded that this fish should not be identified as Pungitius pungitius, but as an independent species in genus Pungitius.