An annotated list of brown seaweeds (Phaeophyceae) from Nakadori Island (northern Goto Islands, Nagasaki, Japan) Author Belleza, Dominic Franco C. 0000-0002-0141-7495 Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki 852 - 8521, Japan & Department of Biology, University of San Carlos, Nasipit, Talamban, Cebu City, 6000, Philippines dfcbelleza@gmail.com Author Tateishi, Hiroto Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki 852 - 8521, Japan caprellidae315@gmail.com Author Tanimae, Shin-Ichiro Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki 852 - 8521, Japan cyphonautes@gmail.com Author Kobayashi, Taishun Faculty of Fisheries, Nagasaki University, Nagasaki 852 - 8521, Japan taishun8125@gmail.com Author Aota, Tomoyuki Faculty of Fisheries, Nagasaki University, Nagasaki 852 - 8521, Japan tommarine290@gmail.com Author Urasawa, Toshiki Faculty of Fisheries, Nagasaki University, Nagasaki 852 - 8521, Japan tu1118kr@gmail.com Author Nishihara, Gregory N. Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki 852 - 8521, Japan & Faculty of Fisheries, Nagasaki University, Nagasaki 852 - 8521, Japan text Phytotaxa 2025 2025-03-18 694 1 1 24 https://doi.org/10.11646/phytotaxa.694.1.1 journal article 10.11646/phytotaxa.694.1.1 1179-3163 16722860 Sargassum horneri (Turner) C. Agardh, 1820 Japanese name: アカモク (akamoku) Basionym: Fucus horneri Turner Type locality: —In the Straits of Corea Description and remarks: —Specimens are densely branched with a thicker main axis at the bottom ( 2.5–3 mm ) and thinner at the top ( 1 mm ). The main axis and the primary branches in the lower portions have small spines while the upper parts are smooth. Branching is alternately bipinnate with the leaves having a prominent midrib with deeply incised and alternating margins. The vesicles are 1–1.5 cm long, cylindrical and are found in the apical regions. The apex of each vesicle is terminated by a leaflet with thin, alternating, deeply pinnatisect margins. In Naname, this species forms dense forests grows to heights reaching over 3–5 m in early to late spring. This species is known for producing large floating rafts in the East China Sea region during macroalgal blooms, known as “golden tide”, and is considered as a nuisance when they drift ashore ( Zhuang et al. 2021 , Qi et al. 2022 ). In 2015, massive rafts of drifting S. horneri from China were recorded to have drifted ashore in many parts of the Goto Islands (Naru, Fukue, Kamigoto), mainland Nagasaki and to the islands in Iki and Tsushima ( Kiriyama et al. 2016 ). Despite this problem, these floating rafts provide refuge for juvenile pelagic species such as yellowtail ( Seriola quinqueradiata ), an important fishery species ( Mizuno et al. 2014 ). Materials examined: —18ECS1-125 (1 to 7)