The keeled box turtle, Cuora mouhotii, is documented in southern Vietnam for the first time, extending the range of the species approximately 300 km southward. The southern population is morphologically similar to the subspecies C. m. obsti and occurs in sympatry with Cuora picturata, a species recently discovered in the wild for the first time. As C. mouhotii is known to hybridize with the closest living relatives of C. picturata (Cuora galbinifrons and Cuora bourreti), this finding allows for the possibility, on the basis of geography, that C. mouhotii and C. picturata may also hybridize in the wild.