Sika deer presence affects the host-parasite interface of a Japanese land leech.

Since the 1990s, increasing populations of a blood feeding land leech () have become a serious issue in several Japanese prefectures, and it may be caused by the increases in sika deer () populations seen over the last quarter of the century. Therefore, this study aimed to reveal the host animal species of . using iDNA (vertebrate DNA isolated from invertebrates) and to test the hypothesis that the increasingly widespread distribution of sika deer results in increased .

Nuclear microsatellite and mitochondrial DNA analyses reveal the regional genetic structure and phylogeographical history of a sanguivorous land leech, , in Japan.

Recent molecular studies have indicated that phylogeographical history of Japanese biota is likely shaped by geohistory along with biological events, such as distribution shifts, isolation, and divergence of populations. However, the genetic structure and phylogeographical history of terrestrial Annelida species, including leech species, are poorly understood. Therefore, we aimed to understand the genetic structure and phylogeographical history across the natural range of , a sanguivorous land leech species endemic to Japan, by using nine polymorphic nuclear microsatellites (nSSR) and cytochrome oxidase subunit one (COI) sequences of mitochondrial DNA (mtDNA).