India, Oct. 31 -- In upper Siang district of Arunachal Pradesh, at the edge of a forest, stood a tree that may already have disappeared. A botanist collected its specimens only once, from a single hillside, and in 2019 described it as Castanopsis pathakii, a member of the oak family. No researcher has returned to look for it since. No conservation plan has been initiated, and even six years later, the species remains absent from global biodiversity databases. Meanwhile, the forest faces pressure from road construction, hydro electric projects and agricultural expansion.

Based on the evidence-single known location, uncertainty over its existence and threats to its habitat-I, along with Joeri Strijk of Alliance for Conservation Tree Genomi...