Chromosome numbers in Orchidantha (Lowiaceae) and their biogeographic and systematic implications

The somatic chromosome numbers of Orchidantha maxillarioides, O. insularis, O. chinensis var. chinensis, and O. chinensis var. longisepala were counted, of which O. insularis and both varieties of O. chinensis are reported for the first time. The chromosome numbers of O. maxillarioides and O. insularis are 2n = 18, apparently diploid, while that of O. chinensis is 2n = 54, and therefore hexaploid (x = 9). We discuss the biogeographic and systematic implications of the different chromosome numbers and ploidy in Orchidantha.