Somatic chromosomes of the nigorobuna (C.auratus grandoculis) obtained from Lake Biwa, two local varieties of the nagabuna (C.auratus buergeri) from Lake Suwa and the Hokkaido district, and two local varieties of the ginbuna (C.auratus langsdorfii) from the Okayama Prefecture and Lake Biwa were studied and compared.Chromosome preparations was performed by the same methods previously described (Kobayasi et al., 1970).
The results showed that the nigorobuna and nagabuna of Lake Suwa and the ginbuna of the Okayama Prefecture had the same diploid chromosome number of 100.Their karyotypes consisted of 10 pairs of metacentrics, 20 pairs of submetacentrics and 20 pairs of acrocentric elements.There was no morphological difference between the male and female karyotypes. On the other hand, 5 females of the nagabuna collected from the Hokkaido district and 4 females of the ginbuna (hiwara) from Lake Biwa had the chromosome number of 156, consisting of 17 pairs of metacentrics, 31 pairs of submetacentrics and 30 pairs of acrocentrics. The populations of the ginbuna and nagabuna in these regions consisted mostly or almost entirely of females.It was proved from these evidences that the nagabuna and ginbuna with triploid state occur not only in the Kanto district but also in the Hokkaido district and Lake Biwa.These triproid females might be arisen by gynogenesis, as has been reported in the ginbuna obtained from the KantO district by Kobayasi (1971) and Kobayasi and Ochi (1972). [Japan Women's University, Bunkyo-ku, Tokyo, 112, Japan (H.K.and H.O.);National Science Museum, Hyakunin-cho, Shinjuku-ku, Tokyo, 160, Japan (N.T.)]