An account of <i>Korthalsia</i> (Arecaceae) rattans and their uses in Thailand

Four species of <i>Korthalsia</i> are found in Thailand: <i>K. flagellaris</i>, <i>K. laciniosa</i>, <i>K. rigida</i>, and <i>K. scortechinii</i>. We present the comparative vegetative morphology, a key to the species, distribution, ecology, preliminary conservation assessments, utilization, and specimens examined. <i>Korthalsia flagellaris</i> is lectotypified here in a second-step. Three Thai <i>Korthalsia</i> species are confined to the peninsular region: <i>K. flagellaris</i>, <i>K. scortechinii</i> and <i>K. rigida</i>. The first, <i>K. flagellaris</i>, is known only from Narathiwat province and is restricted to peat swamp forests. The second, <i>K. scortechinii</i>, is myrmecophilous and found only in Narathiwat in lowland tropical evergreen rainforests. The third, <i>K. rigida</i> has a wider distribution and is known from Ranong, Trang and Narathiwat provinces in lowland tropical evergreen rainforests. Lastly, <i>Korthalsia laciniosa</i> is the most widespread species of the genus in both the south-eastern and peninsular regions of Thailand in lowland tropical evergreen rainforests. All Thai <i>Korthalsia</i> species are currently assessed as Least Concern (LC) under the IUCN conservation status. In Thailand, <i>Korthalsia</i> is used for traditional tools, furniture components, and fishery equipment. Its stems are valued in local crafts, while the young shoots are occasionally consumed as food.