New record of Sargassum denticarpum Ajisaka (Fucales, Phaeophyceae) from Iriomote Island (Ryukyu Archipelago, Japan)

Researchers report the first confirmed occurrence of Sargassum denticarpum, a species previously known only from Vietnam, in Iriomote Island, Japan. This discovery suggests a northward expansion of tropical and subtropical Sargassum species, likely driven by rising sea temperatures in the western Pacific. The identification was based on morphological traits—such as terete primary branches, dentate leaves, and spherical vesicles—and molecular analysis of internal transcribed spacer 2 (ITS2) sequences, which matched those of Vietnamese specimens. The study highlights the potential impact of climate change on marine biodiversity in the Ryukyu Archipelago, a region at the northern limit for these species.

Shimabukuro, H., Kawane, M., & Hamaguchi, M. (2012). New record of Sargassum denticarpum Ajisaka (Fucales, Phaeophyceae) from Iriomote Island (Ryukyu Archipelago, Japan). Botm, 55(3), 209–215. https://doi.org/10.1515/bot-2012-0107