Cytological Study of Begonia Sect. Diploclinium (Begoniaceae)

Previous chromosome information is restricted to 13 species in the Asian Begonia sect. Diploclinium. Here we present the first chromosome counts of three species, as well as confirmed their chromosome numbers of five species. Among three species investigated for the first time, the chromosome number of 2n= 18 and 2n= 32 are new counts in the section. Additionally, we provide the karyotypes of eight species for the first time. Among ca. 135 species in sect. Diploclinium, chromosome numbers of 16 species are available together with the present and previous reports. Among 16 species, they show diverse chromosome numbers with 2n= 18, 22, 24, 26, 30, 32, 36, 46, and 54. B. wenshanensis with 2n= 18 is the lowest chromosome number in the section and the third lowest chromosome number in Begonia. We suggest that B. coptidimontana with 2n= 32 is tetraploid origin with the basic chromosome number ofx= 8. We discussed the chromosome evolution in Begonia sect. Diploclinium.