Karyotypes of Whytockia (Gesneriaceae)

The karyotypes of the genus Whytockia was investigated in order to reveal its systematic position in the tribe Klugieae and the evolution of karyotypes within this genus. The chromosome numbers are 2n＝18 with their length over 2.0 µm in all the investigated species of Whytockia, which represents the most primitive characteristics in the tribe Klugieae. This paper suggests that x＝9 be the primitive basic number of chromosomes in the Klugieae. The morphology of the resting nuclei in Whytockia belongs to the complex chromocenter type. The chromosomes at mitotic prophase are classified into the gradient type. The evolution of karyotypes in Whytockia is toward increase of the chromosomes with submedian centromeres and especially those with subterminal centromeres. The karyotype of the variety W. tsiangiana (Hand.-Mazz.)A. Weber var. wilsonii A. Weber is distinctly different from that of W. tsiangiana var. tsiangiana, which conforms well with the gross morphology. This paper suggests that this variety be separated from W. tsiangiana as an independent species with affinity to W. bijieensis.