We developed 10 microsatellite markers for Plagiogyria koidzumii, a critically endangered fern species found on Iriomotejima Island in the Ryukyu Archipelago, Japan and in Taiwan. These markers showed polymorphism among 65 wild individuals from Iriomotejima Island; the number of alleles per locus was 2-14, and mean observed and expected heterozygosity in the largest population were 0.276 and 0.277, respectively. A genetic structure analysis using these markers indicated clear genetic differentiation even within the narrow geographic range (ca. 10 × 8 km) on Iriomotejima Island. These microsatellite markers should be valuable for measuring genetic diversity and comparing genetic structure within and between populations.
Keywords: Iriomotejima Island; Ryukyu Archipelago; genetic structure; management unit; national endangered species.