Lazarus taxon
taxon that disappears for one or more periods from the fossil record, only to appear again later;likewise in conservation biology and ecology, it can refer to species or populations that were thought to be extinct, and are rediscovered
en-US/ˈlæzəɹəs ˈtæksən/
en-GB/ˈlæzəɹəs ˈtæksən/