Molecular phylogeny and chromosomal evolution of endemic species of Sri Lankan Anacardiaceae.
Family Anacardiaceae comprises 70 genera and approximately 985 species distributed worldwide. Sri Lanka harbours 19 species in seven genera, among these 15 are endemics. This study focuses on regionally restricted endemics and native Anacardiaceae species, which have not been investigated before at molecular and cytological level. Nuclear rDNA ITS and plastid matK regions were sequenced for ten species, having nine endemics and one native, and incorporated into the existing sequence data for phylogenetic analyses. The topologies resulting from maximum parsimony, maximum likelihood and Bayesian inference are congruent. Family Anacardiaceae forms a monophyletic group having monophyletic subfamily Anacardioideae and paraphyletic subfamily Spondioideae. Tribes Anacardieae, Semecarpeae and Rhoeae form subclades within the major clade of Anacardioideae. All the endemic species occupy correct position in the molecular phylogeny as per the existing classification except for Campnosperma zeylanica, which shows a close relationship to members of the subfamily Spondioideae. The position of non-native species Trichoscypha acuminata also remains unclear. Chromosome counts and karyograms were constructed for five endemic species. The chromosome numbers incorporated in the tree range from 2n = 28-58. Species of tribe Rhoeae have the lowest chromosome number (2n = 24, 28, 30) while species of tribe Semecarpeae have the higher numbers (2n = 50, 52, 58). Chromosome numbers mapped on the phylogeny shows that dysploidy had played a role in the evolution of the species of the family Anacardiaceae in Sri Lanka.