イシガイ類とその生態環境の保全―カワシンジュガイ科，イシガイ科の分類体系変更に着目して―

抄録

In recent years, the classification system of Unionoida (Margaritiferidae, Unionidae) has undergone major changes from conventional methods by shell morphology, due to breakthroughs in approaches based on molecular phylogenetic analysis. We compared the classification system trends of the Margaritiferidae and Unionidae distributed in Japan, and pointed out that there is a time lag to the classification determinations of the latter. Although the scientific names have been changed, the existence, distribution, and ecological information (ex. host fish for glochidia) of two Japanese margaritiferids have been established, and conservation measures and regulations based on the Red List and laws can be expected. On the other hand, the Unionidae consisted of 3 subfamilies, 11 genera and 15 species has increased to 2 subfamilies, 13 genera and 26 species (excluding alien species) by the new classification system reported in 2020. Therefore, information on the distribution and ecology of many new species must be elucidated. A new classification system will be assumed the further revision, especially for the genus Sinanodonta, and the risk of some local populations extinction increase before clarifying the actual situation of species. We are now proceeding to clarify the early life stage of some Unionoida mussels (ex. parasitic stage, salinity tolerance), but insufficient knowledge of the life cycle of Unionoida has prevented the establishment of complete ex-situ conservation methods. Conversion project of numerous reservoirs are that the most important habitats for Unionidae species pressing forward in Japan. In light of this situation, it is hoped that the new classification system that can serve as a basis for on-site conservation will spread throughout as soon as possible to realize comprehensive conservation.