Species Diversity of Animals in Japan pp 319-340
Diversity of Leeches from Japan: Recent Progress in Macrophagous and Blood-Feeding Taxa
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The species diversity of the leeches from Japan and recent progress in taxonomic and molecular phylogenetic studies on macrophagous and blood-feeding taxa are reviewed. At present, 64 species are known in Japan, which are classified into 38 genera in 9 families. Recent taxonomic and molecular phylogenetic analyses have revealed that the terrestrial macrophagous genus Orobdella is the most diverse taxon among the genera distributed in Japan. The phylogenetic relationships and geographic distributions of Orobdella species suggest that this genus has been highly influenced by geological events and geographic boundaries. In contrast, phylogenetic relationships between blood-feeding species of the genus Haemadipsa show that Japanese species do not form a monophyletic group, suggesting multiple origins of the species. Phylogenetic relationships of Haemadipsa rjukjuana shed light on the incongruence between its genetic structure and geographic distances. The results indicate that blood-feeding leeches have been dispersed via long-distance migrants. The low genetic diversity of freshwater predatory Mimobdella in the Ryukyu Islands, as well as the presence of the freshwater-introduced species in Japan, indicate the possibility of the influence of human activities on the present distribution of freshwater species.