Rediscovery and conservation of Lithocarpus kostermansii Soepadmo (Fagaceae), an endemic and endangered tree species in Java, Indonesia

Lithocarpus kostermansii Soepadmo (Fagaceae) is an endemic tree confined to the western part of Java Island, Indonesia. The IUCN Red List classifies the species as Endangered (EN) based on the assessment conducted more than 20 years ago. The species is not known to be present in ex-situ collections. After more than 5 decades since the last herbarium specimen was collected in 1964, here we reported the rediscovery of L. kostermansii in Sawarna, Lebak Regency, Banten Province. The species identity was confirmed by comparing the herbarium and living specimens newly collected with the type specimen image and protologue description. This study contributes new information on the tree morphology through photos of living plants made in the field. It also updates the threats to its natural habitat and provides additional locality information for the species. To enhance the conservation of the species, we collected and cultivated saplings of the species and these are growing in Bogor Botanic Gardens as part of their ex-situ conservation collections. Based on our findings, we proposed a new IUCN Red List assessment for L. kostermansii of EN A2c, B1 + 2ab(i,ii) as it is considered to be facing a very high risk of extinction in the wild due to forest degradation and land conversion.