Meristic and morphometric variations in fluvial Japanese charr between river systems and among tributaries of a river system

Meristic and morphometric characters of local populations of fluvial Japanese charr, Salvelinus leucomaenis, which have been isolated above dams and a waterfall, were compared between river systems (Naka and Tone rivers, central Japan) and among the tributaries of the Naka River (Ashinagasawa, Akasawa, Ushirosawa and Moto-okashirasawa streams). Between the river systems, there was a significant difference in the mean number of dorsal fin rays, pyloric caeca, white spots under the lateral line and the proportion of the diameter of the white spots to the diameter of the pupil, respectively. On the other hand, among the tributaries within a river system, a significant difference was occurred in the mean number of anal fin rays, pored scales on the lateral line, gill rakers, vertebrae, pyloric caeca, white spots under the lateral line, white spots on the surface of the gill covers and the proportion of the diameter of the white spots to the diameter of the pupil, respectively. A dendrogram based on data of the meristic and morphometric characters showed that the population of the Tone River was included within the variation detected among the tributary populations of the Naka River. Meristic and morphometric characters of Japanese charr varied not only between river systems but also among tributaries within a river system.