西日本3河川からのCymbella compactiformisの出現

抄録

After 2020, we discovered a Cymbella species from rivers in Western Japan that does not match any native species in Japan. The diatom was identified as Cymbella compactiformis B.Liu & D.M.Williams. It was found in Amano River and Inukami River flowing into Lake Biwa, Shiga Prefecture, and in Yakiyama River in the Onga River System, Fukuoka Prefecture. The populations sampled from the three rivers mostly matched the original description in valve length, breadth, stria and areola density, but their valve ends were less capitate than those of the type population. Cymbella distalebiseriata–liyangensis species complex, which may have been recently introduced from China, is also found in all three study sites. Recently Cymbella species regardless of native and alien have bloomed in Japanese freshwaters and have caused damage to fisheries. Therefore, the spread of C. compactiformis and its impact on river ecosystems should be monitored carefully.