Chromosome numbers can be helpful in understanding the taxonomy and phylogenetic patterns within plant groups. Primulina sensu lato (s. l.), a genus that has recently been redefined and expanded to include all species of Chiritopsis, two of Wentsaiboea and all of section Gibbosaccus of Chirita, has not been well documented cytologically. In the present study we determined the chromosome numbers of fourteen species, three varieties and seven undescribed taxa of Primulina s. l. using conventional rapid squash techniques. In addition, three species of its closest ally, Petrocodon sensu lato (s. l.), were also investigated cytologically. With the exception of Primulina tabacum, all counts are new. A high stability of chromosome number, 2n=36, based on x=18, was recorded in Primulina s. l. Chromosomes were relatively small in size, with mostly metacentrics and submetacentrics predominating. Although slight variation in chromosome size occurs among taxa, the overall homogeneity of chromosome morphology and pattern of basic chromosome number conforms with the results of molecular phylogenetic studies, which strongly support the monophyly of Primulina s. l., and also recent taxonomic treatment. Interestingly, the possession of the same chromosome numbers together with similar chromosome morphology, indicates that Primulina s. l. and Petrocodon s. l. are closely related, which is consistent with the molecular phylogeny of these genera.
New Chromosome Counts and Their Taxonomic Implications in Primulina sensu lato (Gesneriaceae)
Publication: Plant Diversity and Resources