Intraspecific Karyotypic Polymorphism and Cytogeography of Lysimachia mauritiana (Primulaceae) on Several Islands in the Okinawa and the Daito Groups of the Ryukyu Archipelago, Japan

Lysimachia mauritiana, a coastal biennial herb, exhibits remarkable karyotypic diversity within the Ryukyu Archipelago of Japan. Across 10 islands, including Amami-Oshima, Tokunoshima, and Iriomote Island, researchers identified five distinct chromosome numbers (2n=16, 17, 18, 19, 20) and 13 cytotypes. Notably, Okinawajima Island showed intra- and inter-populational polymorphism in northern and western areas facing the East China Sea, while southern, eastern, and northeastern regions facing the Pacific Ocean exhibited a single cytotype per locality. Additionally, the study documented the presence of a previously unknown cytotype (20 (4m) TS), likely originating from currents in southern Taiwan or the Philippines, marking its first recorded occurrence in Japan.

Kono, Y., Hoshi, Y., Setoguchi, H., Yokota, M., & Oginuma, K. (2016). Intraspecific Karyotypic Polymorphism and Cytogeography of Lysimachia mauritiana (Primulaceae) on Several Islands in the Okinawa and the Daito Groups of the Ryukyu Archipelago, Japan. Cytologia, 81(4), 431–437. https://doi.org/10.1508/cytologia.81.431