Emydomyces testavorans is a fungal pathogen associated with mild to severe shell lesions in aquatic turtles. The fungus has been described in wild and managed turtles in North America, but no data is available on its presence in other parts of the world. During investigations into the cause of shell lesions in a managed collection of critically endangered Zhou’s box turtles (Cuora zhoui) in Germany, Emydomyces testavorans was detected by PCR in samples from one animal. Fungal hyphae were detected in similar lesions from another turtle. Following this first detection, 108 chelonians from the same collection were tested for the presence of Emydomyces testavorans in combined oral-, cloacal, and shell swabs. Emydomyces testavorans was detected in 39 (36%) animals, including 23 Zhou’s box turtles, eight Vietnamese three-striped box turtles (Cuora cyclornata), five yellow-headed box turtles (C. aurocapitata), one Pan’s box turtle (C. pani), and two Sulawesi forest turtles (Leucocephalon yuwonoi). None of the Bourret’s box turtles (Cuora bourreti) or McCord’s box turtles (Cuora mccordi) kept in the same room as the affected animals tested positive. Disease associated with infection was observed to be most severe in the Zhou’s box turtles. This detection of Emydomyces testavorans in a new geographic region and in several critically endangered species in which it has not been previously reported is a cause for concern and indicates that this pathogen is globally more wide-spread than previously known.