Detection of the Fungus Batrachochytrium dendrobatidis in Anurans from the Semiarid Region of Brazil: new Infection Records for Endemic Species

Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), has affected amphibians globally since the 1970s, being considered the main cause of their decline worldwide. The present study is the first to assess the presence of Bd in anuran populations in dry and wet tropical forests in Ceará state, northeastern Brazil. Samples were collected in different environmental landscapes throughout the dominant dry forests of the Caatinga and and the relict moist tropical forest (brejos de altitude) in the localities of the Monte Alegre Private Natural Heritage Reserve, Ibiapaba Plateau, Serra de Maranguape, Araripe Plateau, Farias Brito, and Campos Sales. The dry forests of Caatinga harbor amphibian species typical of open areas, while relict moist tropical forests possess endemic and potentially threatened species. The Caatinga is a peculiar Brazilian biome that has been neglected in scientific research and conservation efforts, highlighting the importance of our study. Anuran skin samples were collected from adults using swabs, and DNA was extracted and amplified by PCR using Bd-specific primers. In total, 125 samples were analyzed, comprising 28 species of eight anuran families, with 20 (71%) of the sampled species testing positive for Bd. This is the first record on Bd infection for Adenomera juikitam, Boana raniceps, Dendropsophus nanus, D. soaresi, Leptodactylus troglodytes, L. vastus, Physalaemus cicada, Pristimantis relictus, Proceratophrys ararype, Pseudopaludicola mystacalis and Scinax x-signatus. Particularly the Bd-positive species Proceratophrys ararype and Pristimantis relictus can be considered as greatest concern, as they were recently described and their known distribution is restricted to the high elevation relictual moist forests.