Cymbella distalebiseriata-liyangensis種複合体の日本からの出現

抄録

After 2020, we discovered distinct Cymbella species from three different rivers in Western Japan; the Amano River flowing into Lake Biwa, the Chikusa River, and the Onga River. They are characterized by having valves with biseriate striae near the apices and uniseriate striae around the center. The population from the Amano River is identified as Cymbella distalebiseriata B.Liu & D.M.Williams, while that from the Chikusa River is more suitable to identify as Cymbella liyangensis W.Zhang, I.Jüttner & E.J.Cox. Those from the Onga River are similar to C. distalebiseriata in the valve shape, but morphometrically more similar to C. liyangensis. Because these two species are very similar in valve outline and stria density except for the difference of areola density, we regarded them as Cymbella distalebiseriata-liyangensis species complex. We would assume that they have recently invaded Japan since, to our knowledge, they have not been reported in Japanese diatom flora.