Abstract/Summary

Korthalsia is a genus of palms endemic to Malesian region and known for the several species that have close associations with ants. In this study, 101 new sequences were generated to add 18 Korthalsia species from Malaysia, Singapore, Myanmar and Vietnam to an existing but unpublished data set for calamoid palms. Three nuclear (prk, rpb2, and ITS) and three chloroplast (rps16, trnD-trnT and ndhF) markers were sampled and Bayesian Inference and Maximum Likelihood methods of tree reconstruction used. The new phylogeny of the calamoids was largely congruent with the published studies, though the taxon sampling was more thorough. Each of the three tribes of the Calamoideae appeared to be monophyletic. The Eugeissoneae was consistently resolved as sister to Calameae and Lepidocaryeae, and better resolved, better supported topologies below the tribal level were identified. Korthalsia is monophyletic, and novel hypotheses of species level relationships in Korthalsia were put forward. These hypotheses of species level relationships in Korthalsia served as a framework for the better understanding of the evolution of ocrea. The morphological and developmental study of ocrea in genus Korthalsia included detailed study using Light and Scanning Electron Microscopy for seven samples of 28 species of Korthalsia, in order to provide understanding of ocrea morphological traits. The new phylogenetic hypothesis allowed homology of ocrea types to be tested. Ancestral reconstructions revealed that the inflated ocreas are not homologous; based on these reconstructions, it is suggested that ocreas that provide domatia for ants evolved more than once. Despite their non-homology, ocreas are remarkably uniform developmentally. New time calibrated trees estimated the divergence time for the Korthalsia crown node to be 19.89 MYR and ocrea to appear 17.06 MYR consistent with the published estimates for other groups. A taxonomic treatment of the ant Korthalsia species was based on material gathered from four herbaria and during the two field trips. Ten species were recognised in the treatment. Descriptions, keys and distribution maps to all species are presented.