The hidden biodiversity of amphibian pathogens

Discovery of additional amphibian chytrid pathogens increases conservation concerns Since the discovery of the salamander chytrid pathogen [ Batrachochytrium salamandrivorans ( Bsal )] ( 1 ), the world has been preoccupied with determining where it does and does not occur ( 2 ) so that policies can be implemented to prevent introduction into unaffected areas ( 3 ). Pathogenic chytrids cause chytridiomycosis, a disease of the skin that can cause mortality and die-offs, including population declines and species extinctions. In the United States—the world's biodiversity hot spot for salamanders and currently free of Bsal —a multinational scientific task force has been created to test the susceptibility of native species and to prepare an emergency response should Bsal be detected ( 4 ). Meanwhile, attention to Bsal 's better-known cousin B. dendrobatidis ( Bd ), another chytrid pathogen that has decimated amphibian populations around the world, has faded, in part because of perceptions that once Bd is present, conservation actions and policy options are limited. On page 621 of this issue, O'Hanlon et al. ( 5 ) remind us that Bd remains a serious threat to global amphibian biodiversity and clarify where and when Bd came from and how it spread.