Chikako Ikebe

Cytogenetic studies of Hynobiidae (Urodela). X Morphological variation of chromosome 10 in ten pond‐type Hynobius from Korea and Japan, with comments on phylogenetic relationships

We have studied karyotypes of ten pond‐type Hynobius collected from 51 localities: H. leechii from Korea, and H. tsuensis, H. dunni, H. nebulosus, H. abei, H. tokyoensis, H. takedai, H. lichenatus, H. nigrescens and H. retardatus from Japan. C‐banding analyses have been performed on the specimens from 38 out of the 51 localities. Among the karyological variations observed, chromosome 10 showed intra‐ and interspecific variations in many species, which we considered suitable for phylogenetic analysis. Our phylogenetic inferences concerning the morphological variation of chromosome 10 in ten pond‐type Hynobius are summarized as follows: 1) similarity in the morphology and the amount of heterochromatin of chromosome 10 in species found in close geographic proximity to each other indicates a close phylogenetic relationship; 2) species distributed in widely separated geographic areas and yet with similar amounts of heterochromatin on chromosome 10 have conserved this chromosomal pattern from a common ancestor; 3) the main evolutionary changes of chromosome 10 are decreases in the C‐positive region and transformation of the biarmed type of this chromosome to the uniarmed type by a pericentric inversion involving the C‐positive region.

Cytogenetic studies of Hynobiidae (Urodela). IX. Karyological characteristics ofHynobius abei Sato by means of R-and C-banding

Chromosomal characteristics of the salamander speciesHynobius abei, from Ohimya (Kyoto) were revealed by the techniques of R-and C-banding. The karyotype ofH. abei was characterized by the shortness of an R-negative (C-positive) band in the terminal region of the long arm of chromosome 2 and a band encompassing the whole short arm of chromosome 10. These two bands inH. abei were the shortest among those of the variousHynobius species that have been examined. Otherwise no differences could be detected betweenH. abei and seven other pond-type species ofHynobius (2n=56) in terms of the banding patterns of 18 specifically identifiable pairs of their chromosomes.

Cytogenetic studies of Hynobiidae (Urodela) XVI. Comparative C-banded karyotype analysis of Pseudohynobius flavomaculatus (Fei et ye), Ranodon shihi (Liu) and Batrachuperus pinchonii (David)

Initial analysis of Pseudohynobius flavomaculatus chromosomes determined the chromosome number of this species to be 2n = 52. A re-examination of Ranodon shihi chromosomes detected 2n = 66 chromosomes, in contrast with a previous finding of 2n = 64. The C-banding patterns of these two species and that ofBatrachuperus pinchonii were compared with each other. Regions of homoeology in the C-banding pattern among these three species represented 33.51–48.30% of the total length of their chromosomes. We also detected two types of chromosome rearrangement in hynobiid species based on the results of the present and previous cytogenetic studies.

Cytogenetic studies of Hynobiidae (Urodela). XIV. Analysis of the chromosome of a Chinese salamander, Batrachuperus pinchonii (David)

The chromosome number of a Chinese salamander, Batrachuperus pinchonii, was re-examined. Adults and embryonic specimens had a diploid number of 66, with 33 bivalents during meiosis, in contrast to previous reported results. Furthermore, when C-banding analysis was performed with embryos, chromosomes with banding patterns homoeologous to those of Salamandrella keyserlingii and Hynobius species were found. It appears, therefore, that Batrachuperus, Salamandrella and Hynobius might be derived from a common ancestral species in eastern Asia.

Chromosomes of Hynobius chinensis Günther and Hynobius amjiensis Gu from China, and Comparison with Those of 19 Other Hynobius Species

Abstract We report for the first time the chromosome numbers, karyotypes and C-banding patterns of Hynobius chinensis and Hynobius amjiensis from the middle-eastern region of mainland China. Both species had a diploid set of 56 chromosomes, with similar karyotypes. Among Hynobius species, the C-banding patterns of H. chinensis and H. amjiensis were the most similar to those of H. leechii from the northern region of South Korea. The chromosome number of H. chinensis and H. amjiensis was identical to that of 11 Hynobius species distributed throughout Korea and Japan. This identity indicates close phylogenetic relationships among the 13 species.

Cytogenetic studies of Hynobiidae (Urodela) XIX. Morphological variation of sex chromosomes pairing behavior of sex lampbrush chromosomes in Hynobius quelpaertensis (Mori) from Cheju Island, South Korea.

Using Giemsa staining, C-banding and Ag-NOR staining techniques, we analyzed chromosomes in adult male and female Hynobius quelpaertensis and in embryos of this species in egg sacs collected from eight localities of Cheju Island, South Korea. Chromosome pair 21 was consistently homomorphic in male specimens, while it was heteromorphic in female specimens, suggesting the occurrence of ZZ/ZW sex chromosome constitution in this species. The W chromosome, being much larger than the Z chromosome, was of three morphologically distinct types: WA, WB and WC. Lampbrush chromosomes examined in the oocytes of one female specimen having the WA chromosome showed that the short arm of the WA chromosome and the long arm of the Z chromosome paired closely and hence are genetically homologous. We also tried to analyze the structural relationship among the three types of W chromosomes based on their C-banding and Ag-NOR patterns.