Karyotype evolution and phylogenetic analyses in the genus C ardiospermum L . ( P aullinieae, S apindaceae)

C ardiospermum L . belongs to the P aullinieae tribe ( S apindaceae) and comprises 16 species. Of these, 12 species are present in S outh A merica and all occur in B razil. C ardiospermum shows the most variable chromosome number of the tribe. Phylogenetic relationships within the genus C ardiospermum , especially with other species of the tribe, are poorly understood. This research focuses on characterisation of the karyotypic features of C ardiospermum using conventional cytogenetic methods, CMA / DAPI chromosome banding and fluorescence in situ hybridisation ( FISH ). To elucidate the phylogeny of the genus, the nuclear markers ITS1 and ITS2 were sequenced and analysed using maximum parsimony and Bayesian inference. C ardiospermum shows important diversity in basic numbers, with x = 7, 9, 10, 11 and 12. All species studied have metacentric and submetacentric chromosomes, some species have subtelocentric chromosomes, while telocentric chromosomes are absent. The interphase nuclei differentiate the C ardiospermum species into two groups. The CMA 3 / DAPI chromosome banding revealed the presence of an AT ‐rich terminal region in C . corindum , C . grandiflorum and C . urvilleoides , whereas GC ‐rich regions were found in C . grandiflorum , C . halicacabum var. halicacabum , C . halicacabum var. microcarpum , C . heringeri and C . integerrimum . FISH revealed syntenic and non‐syntenic distribution of the 18‐5.8‐26 S and 5 S rDNA . The syntenic distribution always occurred in the short arms of the same chromosome in all of the species. The phylogenetic relationships reveal, in part, the taxonomic arrangement of the genus C ardiospermum .