Drepananthus khaosoi sp. nov. (Annonaceae) from southern Thailand, with molecular phylogenetic reconstructions

Drepananthus khaosoi sp. nov., a new species from southern Thailand is described and illustrated. It is morphologically most similar to D. ridleyi, especially in the very narrow and elongated petals, but differs in leaf blade size, leaf base, monocarp shape and appearance, monocarp width, length of monocarp stipe, pericarp thickness and seed arrangement. Molecular phylogenetic analyses using chloroplast DNA regions (matK and rbcL exons; trnL intron; atpB-rbcL, psbA-trnH and trnL-trnF intergenic spacers) and including 18 Drepananthus species confirm the monophyly of Drepananthus, but the relationships within the genus are largely unresolved, including a failure to elucidate a sister group of D. khaosoi. The conservation status of the new species is provisionally assessed as Critically Endangered.