Distribution of Haemadipsa japonica in Japan before the 1980s

Abstract

Since the 1990s, the range of the land leech Haemadipsa japonica has expanded to include areas of human activity, possibly due to increases in mammalian populations, which has become a problem in several Japanese prefectures. Knowledge of the origins and past distributions of the currently expanding populations of H. japonica is imperative to the successful implementation of countermeasures. Although previous studies have examined past distributions, much knowledge is still lacking, especially prior to 1945. Here, we surveyed past distributions of H. japonica based on academic and mountaineering literature in addition to travelers' journals published between the mid-Edo era (the 1770s) and the 1980s, prior to their range expansion. We reconstructed the distributions of this species for two periods: between the 1770s and 1945 and between 1946 and the 1980s, and compared the reconstructed distributions to the present distribution. Our results showed that H. japonica has been found in mountainous areas in parts of Tohoku, Chubu, Kii peninsula, and Kyushu since before 1945. In contrast, populations from Mt. Hikosan, Kyushu, and Mt. Amagi, Izu, may have disappeared before the mid-Meiji era.