Rediscovery and conservation of Garcinia klabang (Clusiaceae), a critically endangered tree last collected in 1857 and previously tagged as possibly extinct

Since 2006, the IUCN has introduced the “Possibly Extinct” tag within the Critically Endangered category (CR(PE)) to identify species that are likely extinct based on available evidence but still have a small chance of survival. Garcinia klabang Miq., a CR(PE) species from the Clusiaceae family, was last collected in 1857 from the Jebus area on Bangka Island, Indonesia. In 2020, the IUCN Red List listed the species as Critically Endangered with the “Possibly Extinct” tag, due to its limited geographic range and the significant threats it faces from forest conversion to agricultural land and oil palm plantations. In this study, we report the rediscovery of G. klabang 168 years after its last collection, in a new location approximately 40 km east of the type locality. A total of 190 G. klabang individuals were recorded at four locations, with most concentrated in Jebus and Riau Silip. Nearly half (44.2 %) being in a mature stage, with a diameter at breast height of up to 31.5 cm and a hight of up to 15 m. These individuals occur across a range of habitats, from heathland forests at low elevations to lowland forests at elevations exceeding 500 m, with slopes ranging from 0° to 35°. The habitats of the species were characterized by higher silt content soil, nutrient-poor and acidic. Based on our findings, G. klabang is still qualified for CR status under criteria CR C2a(i) with the tag “Possibly Extinct” has been removed. Additionally, we collected plant materials for ex-situ conservation in Cibodas Botanic Gardens. We also conducted species distribution modelling to map the suitable habitat for this species. This map can help guide future population surveys and aid in selecting appropriate sites for habitat protection and natural population enrichment programs.