Where is the highest concentration of unique mammals to be found?

A team of American and Filipino authors has found that Luzon Island, in the Philippines, has the world’s greatest concentration of unique species of mammals. Their 15-year project, summarized in a paper published in the scientific journal Frontiers of Biogeography, has shown that out of 56 species of non-flying mammal species that are now known to live on the island, 52 live nowhere else in the world. Of those 56 species, 28 were discovered during the course of the project. The leader of the project is Lawrence Heaney, the Negaunee Curator of Mammals at The Field Museum in Chicago. As of 2016, nineteen of the species have been formally described in scientific journals, and nine are currently in process.