First Detection of Ranavirus Infection in Threatened Brazilian Anurans.

Amphibians are the most threatened vertebrate group worldwide, with emerging infectious diseases playing an important role in their ongoing declines. Although the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) has received considerable attention, viruses of the genus Ranavirus (Rv) remain less explored, particularly in South America. In this study, we report the first detection of Rv in two threatened amphibian species from Brazil. Specifically, we found infected tadpoles of the redbelly toads Melanophryniscus admirabilis (1.4% prevalence) and Melanophryniscus biancae (24% prevalence) in the southern Brazilian Atlantic Forest. Our findings highlight the need for expanded surveillance and pathogen monitoring in threatened anuran populations, particularly those with limited geographic distributions and threatened with extinction. Understanding Rv dynamics and potential interactions with Bd and other stressors is essential to guiding future conservation strategies for Melanophryniscus spp. and other vulnerable amphibians in the Atlantic Forest biome.