Climatic driver of chytrid prevalence in the Critically Endangered Admirable Redbelly Toad

• First record of chytrid in the microendemic Melanophryniscus admirabilis; • Chytrid was consistently infecting the only known M. admirabilis population; • Temperature influences chytrid dynamics in a threatened toad population; • Chytrid had no effect on the body condition of M. admirabilis. Global warming is driving shifts in rainfall and temperature patterns, and projections indicate an increase in frequency and intensity of climate anomalies. These changes influence wildlife disease dynamics, affecting pathogen development, host behavior, physiology, and disease susceptibility. Understanding the intricate interplay between climatic anomalies and emerging pathogens in amphibians is essential to inform conservation efforts targeted towards this highly threatened vertebrate group. We therefore investigated the dynamics of the waterborne chytrid fungus Batrachochytrium dendrobatidis ( Bd ) in the microendemic and Critically Endangered amphibian Melanophryniscus admirabilis under climatic anomalies and seasonal climatic fluctuations. Additionally, considering the sublethal effects of Bd in our focal host species, we tested whether Bd infection explains the variation in host body condition. We found that Bd was consistently infecting Admirable Redbelly Toad population for more than three years. Our results point to links between Bd prevalence and seasonal temperatures, indicating that temperature plays a crucial role in Bd transmission among toads. However, we failed to find an effect of Bd infection on host body condition. The insights gained from this study can improve conservation efforts and help elucidate the links between climatic factors and chytrid infection, informing management plans for threatened amphibian populations.