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

Chromosome numbers were determined in 23 accessions representing 21 species hitherto belonging toChirita(Gesneriaceae), a genus that has recently been remodelled and split into five different genera:Damrongia,Henckelia,Liebigia,MicrochiritaandPrimulina. The previously monotypicPrimulina tabacumwas 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 genusChirita, were analysed in the light of the taxonomic revision of the genus and published phylogenetic data.Chiritawas 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,Henckeliawas found to be as equally heterogeneous as the erstwhileChirita,Microchiritaincluded only two chromosome numbers, 2n= 18 and 34, the three species ofDamrongiawere uniform with 2n= 18, while species belonging to the extendedPrimulinashowed 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 generaHenckelia,Microchiritaand, to a lesser degree,Primulina.