A small Japanese salamander, Hynobius naevius, long considered a single species, has recently proven to include two groups (Group A=large type and Group B=small type) that are split at the species level. We compared the type series of H. naevius with specimens of the two groups to clarify which of them corresponds to true H. naevius, and to estimate the type locality of this species, which was not given in detail in its original description. Results of various morphological analyses altogether indicated that the type series belongs to Group A and that the population sample from Mt. Taradake, located on northwestern Kyushu, is most similar to the type series. Therefore, the type locality of the species is estimated to be in northwestern Kyushu. These results also indicate that Group B obviously represents a cryptic species whose scientific name remains to be determined.