- APG : Acta phytotaxonomica et geobotanica (ISSN:13467565)
- vol.57, no.2, pp.129-154, 2006-08-30
A taxonomic study of the seagrass genus Halophila Thouars concludes that eight distinct taxa, including four new species, occur in Japanese waters. Past literature indicated that the name of H. ovata Gaud. is illegitimate, thus a new species name, H. gaudichaudii J. Kuo, with a description is provided. Halophila major (Zoll.) Miq. has been reinstated to a distinct taxon, with H. euphlebia Mak. as a synonym. The other three new species, H. nipponica J. Kuo, H. mikii J. Kuo, and H. okinawensis J. Kuo are endemic to Japan, while H. gaudichaudii, H. ovalis (R. Br.) Hook. f., H. major, H. minor (Zoll.) den Hartog and H. decipiens Ostenf. are extended from Indo-West Pacific regions to reach their northern distributional boundaries in southern Japan. Halophila okinawensis and H. gaudichaudii are restricted to Ryukyu Islands and H. mikii only occurs in Tanegashima and Yakushima Islands. Halophila nipponica is widely distributed in temperate Japan except for Hokkaido Island, while the tropical H. major has additional colonies confined to Wakayama Prefecture in Honshu and Tokushima and Kochi Prefectures in Shikoku. Typifications, morphological descriptions, habitat and biological information, illustrations and distribution maps are presented for each taxon. Biogeographical distribution of the Japanese species is discussed in relation to the effect of currents.