NEW CHROMOSOME COUNTS IN OLD WORLD GESNERIACEAE: NUMBERS FOR SPECIES HITHERTO REGARDED AS CHIRITA, AND THEIR SYSTEMATIC AND EVOLUTIONARY SIGNIFICANCE

Abstract

Chromosome numbers were determined in 23 accessions representing 21 species hitherto belonging to Chirita (Gesneriaceae), a genus that has recently been remodelled and split into five different genera: Damrongia, Henckelia, Liebigia, Microchirita and Primulina. The previously monotypic Primulina tabacum was also investigated. Counts for 19 species were new, two were confirmatory and two gave different numbers from previously published counts. The results here, together with previously published cytological data for the erstwhile genus Chirita, were analysed in the light of the taxonomic revision of the genus and published phylogenetic data. Chirita was originally highly heterogeneous in chromosome numbers, including seven different somatic numbers, 2n = 8, 18, 20, 28, 32, 34 and 36. Among the five remodelled genera, Henckelia was found to be as equally heterogeneous as the erstwhile Chirita, Microchirita included only two chromosome numbers, 2n = 18 and 34, the three species of Damrongia were uniform with 2n = 18, while species belonging to the extended Primulina showed only one basic number, x = 18, with 15 samples being diploid, and one being tetraploid. In the light of recent phylogenetic studies, polyploid as well as dysploid changes appear to have shaped the genomes of the newly defined genera Henckelia, Microchirita and, to a lesser degree, Primulina.