云南高黎贡山白颌大角蟾的核型,C—带及Ag—NORs的研究

比较了云南高黎贡山地区的贡山独龙江和腾冲大蒿坪白颌大角蟾（Megophryslateralis）两个地理种群的核型、C-带和Ag-NORs结果表明，两个地理种群在核型和带型上都有差异两个地理种群的核型均为2n＝26，NF＝52染色体形态差异不明显，而次缢痕的位置完全不同，贡山独龙江标本的次缢痕位于No．2的长臂上近着丝点处，腾冲标本的次缢痕位于No．5的短臂上近着丝点的部位在腾冲标本中发现一雄性个体中有一条额外的染色体，可能是B染色体两地标本的C-带差异不太显著，贡山独龙江标本的C-带相对较为显著．贡山独龙江标本的Ag-NORs位于No．2长臂近着丝点处，与次缢痕的部位对应，两条同源染色体上大小有显著差异．腾冲标本的Ag-NORs位于No．5短臂上近着丝点处，与次缢痕的部位对应依据核型和带型的比较，对白颌大角蟾的分类和进化问题进行了讨论。

STUDY ON KARYOTYPE, C-BANDING AND Ag-NORS OF TWO GEOGRAPHIC POPULATIONS OF MEGOPHRYS LATERALIS FROM GAOLIGONSHAN, YUNNAN PROVINCE

Karyotype , C-banding and Ag-NORs of two populations of Megophrys lateralis from the Gaoligongshan Mountains in western Yunnan were examined and characterized. The results demonstrate that the karyotypes of Megophrys lateralis from Gongshan and Tengchong are composed of 2n = 26(NF = 52). Althoughkaryotypes of the two populations resemble each other in diploid number and most chromosome shapes, the differences in both conventional and banded karyotypes are found in the following respects: (1 ) Secondary constrictions of foe samples from Gongshan on long arms of pair No .2 adjacent to centromere, while those of karyotype of the samples from Tengchong were located on short arms of pair No .5; (2) An extra small chromosomewas found in a male from Tengchong, which is possibly a B-chromosome. This chromosome was not found in thesamples from Gongshan . (3) Ag-NORs of the samples from Tengchong are on long arms of pair No. 2, andthose of the samples from Gonshan are on Shorl arms of pair No. 5. (4) C-banding karyotype demonstrates thatthe samples from Gongshan have more developed heterochromatin than those from Tengchong. No heteromorphic chromosomes were found related to sex in the two geographic populations. The cytogenetic and taxonomic implications of the findings are discussed in this paper.