Molecular phylogenetic and morphological analyses support recognition of a new species of Vincetoxicum (Apocynaceae, Asclepiadoideae) from eastern Thailand

An unknown Vincetoxicum species has recently been discovered in eastern Thailand. It is a twiner that resembles its morphology flexuosum s.l., variable taxon widely occurring from tropical Asia to Australia. Morphological examination showed despite similarities growth habit, leaf shape, gross appearance of inflorescence structure and flower colour, these two elements exhibit substantial differences both vegetative floral characters clearly distinguish one the other, particularly shape bud indumentum on corolla lobes. In addition, we also evaluated phylogenetic relationships based DNA sequence data for ITS, trnT-L, trnL trnL-F markers this new sp. with congeners (including, inter alia, sequences varieties recognized Thailand V. i.e. var. tenue). The analyses demonstrated not closely related taxa s.l. Instead, it was retrieved as sister clade containing African taxa, caffrum, lycioides fleckii. Therefore, integrated molecular phylogeny revealed be well-defined distinct well all other known congeners. morphological similarity between likely resulted convergence, leading various taxonomic complications. We here describe species, sangyojarniae, nov., provide detailed description, illustration photographs. Moreover, monophyletic actual circumscription, reconsideration suggested.