Taxonomy, new distribution, and DNA barcoding of the rare alga Chara altaica (Charales, Charophyceae) in Japan

Chara altaica A. Braun (Charales, Charophyceae) is distributed mainly in Central to East Asia, and inhabits fresh and brackish water environments. In Japan, C. altaica is listed as a data-deficient species, according to the Japanese Red List, because it was recorded at only one locality in eastern Japan at Lake Takahoko-numa, Aomori Prefecture. In this study, we identified a new locality of C. altaica in western Japan at Tsubasa-ike pond, a shallow lake in Yonago Waterbird Sanctuary, Tottori Prefecture, based on DNA barcoding of herbarium specimens using two DNA barcoding regions [the chloroplast RuBisCO large subunit (rbcL) and maturase K (matK) genes]. This is the oldest documented occurrence of C. altaica in Japan, although we did not observe C. altaica in our recent field survey in Tsubasa-ike pond. The morphological characteristics of the thalli of C. altaica are consistent with those described by other studies. Moreover, our genetic analyses using two DNA barcoding regions revealed a close genetic relationship between C. altaica specimens from Japan and Central Asia.