Sargassum thunbergii (Mertens ex Roth) Kuntze, 1880

Belleza, Dominic Franco C., Tateishi, Hiroto, Tanimae, Shin-Ichiro, Kobayashi, Taishun, Aota, Tomoyuki, Urasawa, Toshiki & Nishihara, Gregory N., 2025, An annotated list of brown seaweeds (Phaeophyceae) from Nakadori Island (northern Goto Islands, Nagasaki, Japan), Phytotaxa 694 (1), pp. 1-24 : 16

Sargassum thunbergii (Mertens ex Roth) Kuntze, 1880

Japanese name: Ưミトラノオ (umitoranoo)

Basionym: Fucus thunbergii Mertens ex Roth, 1800

Syntype locality: — China and Japan seas

Description and remarks: —The thalli of the specimens are bushy and can reach to about 45–50 cm high. The main axis is terete with a diameter of about 1–1.5 mm. The phylloids are slender and filiform, 3–5 mm long and 0.5–1 mm wide with smooth or dentate margins. The vesicles are on stalks, ovate or fusiform with mucronate tips. Plants are dioecious and may form branches which contain the terete receptacles that are 5–10 mm long. Branches may arise from the main axis and branch lengths are usually longer near the base and shorter near the apex. This species forms a thick forests in Yokoura along the sheltered side of the small embayment on the rocky patches near the sandy areas in mid-late spring. In Naname, it was found along the periphery of the S. horneri forests in early spring.

Materials examined: —18ECS1-4 (2, 3 and 10–14)