Correction of karyotype of diploid Beesia calthifolia and discovery of a tetraploid cytotype
YANG Qin Er (Laboratory of Systematic and Evolutionary Botany, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093)
In this paper, the chromosomes of Beesia calthifolia were re examined. In the 40 plant individuals of the population from Xinning County, Hunan Province, central China, one was found to be tetraploid with the karyotype formula of 2n=4x=32=16m+8sm+4st+4t, and the remaining were all found to be diploids with the karyotype formula of 2n=2x=16=8m+4sm+2st+2t. All the 10 individuals of the population from Cangshan Mountain, Dali City,Yunnan Province, southwestern China, were unexpectedly found to be tetraploids with the karyotype formula of 2n=4x=32=16m+8sm+4st+4t. Tetraploid cytotype was reported in this species for the first time. Based on the results and those previously reported, it is considered that there may exist some errors in the results of the karyotype analysis of this species previously reported by Shang(1985). He might have at least mistakenly recognized the centromere position of the fourth pair of chromosomes. This pair of chromosomes should have subterminal rather than median centromeres. Furthermore, the karyotypic differences of B. calthifolia and B. deltophylla were analyzed and the systematic position of the genus Beesia was discussed in detail.