[A new karyotype of Drosophila albomicans]

In the paper, we present a new karyotype of D. albomicans found in the populations from Southeast China. Short chromosome IV of D. albomicans has been reported in Thailand populations while long type was discovered in Taiwan populations. However, we found that long and short chromosome IV coexisting in the same somatic cells. The individuals which contained the "hybrid" cells were collected from Shanghai, Fuzhou, Xiamen and Shenzhen, China. Moreover, the three karyotypes could be detected in each population mentioned above in other words, the populations showed a pattern of karyotype polymorphism. Furthermore, our observation disclosed that the new karyotype was unstable. Its frequency decreased with increasing breeding generation. Since the geographic locations of these populations just lies between the regions of double long and double short type's populations, this new karyotype seems a intermediate transitional type during the variance process of D. albomicans.