Sri Lanka

Sri Lanka has the highest biodiversity per unit area among Asian countries in terms of flowering plants and vertebrates, with the exception of birds.

An excerpt from the article 24 facts about Sri Lanka

Among all flowering plant species on the island, as many as 27% are endemic, and among mammals, endemic species account for 22%. Some ornithologists consider 33 species of birds found in Sri Lanka to be endemic, while others recognize only 27.