KARYOTYPES IN 6 SPECIES OF PUFFERFISHES GENUS TAKIFUGU (TETRAODONTIDAE, TETRAODONTIFORMES)

Chromosome studies were carried out on six species of genus Takifugu: T. niphobles, T. pardalis, T. poecilonotus, T. radiatus, T. rubripes, and T. xanthopterus, which are found commonly in coastal waters of northern Kyushu, Japan. Chromosome preparations were made from kidney tissues with conventional air-dry method. Chromosome numbers were determined as 2n=44 and new arm numbers were determined as 46 in all the species. Karyotype analyses indicated to have 4 m + 16 sm + 24 st or ac in T. niphobles, 6 m + 16 sm + 22 st or ac in T. pardalis, 12 m + 10 sm + 22 st or ac in T, poecilonotus, 8 m + 14 sm + 22 st or ac in T. radiatus and T. xanthopterus, and 10 m + 12 sm + 22 st or ac in T. rubripes. Fundamental number (FN) of five species were determined as 66 except T. niphobles which had 64 in FN. Therefore, it was estimated that the chromosome complements of these fishes were remarkably similar. So, the occurrence of the natural hybrids of this genus Takifugu might be related with similarity of their karyotypes.