Sample collection
From spring 2019 to early winter 2021, a total of 31 sites (27 field
sites and 4 captive sites) were surveyed throughout the Guangxi region
in China (Fig. 1A), which shares its southwestern border with Vietnam, a
country known to harbor Bsal (Laking et al., 2017). The pathogen
was detected in an individual of a salamander species, Pachytriton
wuguanfui in Guangxi region (Yuan et al., 2018). It is now known that
basal Asian and global lineages of Bd exist in this region (Fig.
1B, Sun et al., 2023). Occasionally, Bsal can spill over from
captive populations into wildlife communities (Cunningham et al., 2015;
Fitzpatrick et al., 2018; Sabino-Pinto et al., 2015). To account for
this, random samples were collected from pet markets and frog farms
within the region. Skin swabs were collected following the sampling
protocol for chytrid pathogens in amphibians, as described in Hyatt et
al. (2007). Water samples were collected from bodies of water forBsal detection in relation to local populations, to be used for
environmental DNA (eDNA) analysis; eDNA can be used for pathogen
detection in the absence of hosts (Kirshtein et al., 2007; Schulz et
al., 2020). For this, approximately 1 L of water was sampled for each
water body, then filtered through the 0.40 μm polycarbonate filter
membrane using a sterile 100 ml syringe.
Ethical clearance for this study was obtained from the Institutional
Animal Care and Use Committee of Guangxi University (GXU2018-048, with
an extension of GXU2020-501).