Cytotaxonomy of two species of genus chrysolaena h. robinson, 1988 (vernonieae, asteraceae) from northeast paraguay

Abstract

Chromosome counts and karyotypes of two species of Chrysolaena H. Robinson 1988 are presented inthis paper. Mitotic analysis revealed that both taxa have x=10, a basic chromosome number consideredcharacteristic of the genus. The chromosome number and the karyotype of C. cristobaliana are reportedfor the first time, as well as a new cytotype and the karyotype of C. sceptrum. Chrysolaena cristobalianashowed heptaploid cytotype with 2n=7x=70 and a karyotype composed of 46 m + 24 sm chromosomes.On the other hand, C. sceptrum presented tetraploid cytotype with 2n=4x=40 and a karyotype with 30 m+ 10 sm chromosomes. Accessory chromosomes were observed in cells of both species. The chromosomeanalysis showed that these species differ in the chromosome number and the total chromosome length,although they showed similar chromosome morphology and asymmetry indexes. The results support theuse of chromosome data in taxonomic treatments of the American members of the tribe Vernonieae.