Presence of the Fungus B. dendrobatidis, but not B. salamandrivorans, in Wild Pyrenean Brook Newts (Calotriton asper) in Spain and France

In the last 20 years, the emergence of chytridiomycosis due to the chytrid fungi Batrachochytrium dendrobatidis (Bd), and the more recently described Batrachochytrium salamandrivorans (Bsal), has caused severe amphibian population regressions across the planet (Bosch et al. 2001; Spitzen-van der Sluijs et al. 2016; Scheele et al. 2019). This has generated an increase in scientific interest to decipher the complex interaction between the environment, the fungus and amphibian hosts, and increased surveillance efforts in many localities (Canessa et al. 2020). Batrachochytrium spp. affect the vital function of the amphibian skin, leading to lethargy or skin discoloration, hyperkeratosis, erosions (even ulcerations in Bsal) of the epidermis, and eventually death (Berger et al. 1998; Weldon et al. 2004; Stuart et al. 2004; Wake and Vredenburg 2010; Martel et al. 2013). Bd is currently found on all continents where amphibians are present (Skerratt et al. 2007), affecting more than 700 species within the three orders of amphibians and has been considered a major threat to amphibian biodiversity worldwide (Crawford et al. 2010; Fisher et al. 2012; Olson et al. 2013; Olson and Ronnenberg 2014).