Sargassum macrocarpum C. Agardh, 1820

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 : 15

Sargassum macrocarpum C. Agardh, 1820

Japanese name: ノコギリモク (nokogirimoku)

Type locality: —ex Japonia

Description and remarks: —Plants are bushy and reaching up to more than 30 cm tall. The main axis has a diameter of about 2 mm, some sections are slightly compressed and winged, bearing serrate margins. Leaves occur on the secondary branches and have deeply incised serrate margins with a faint midrib. Vesicles are found on the base of the tertiary branches, having a spherical, elliptical or obovoid shape with a leaflet on apex. This species of dioecious and the reproductive parts are found on the terminal branches around the month of June until September.

This is a perennial species and is widely distributed around Yokoura, forming dense algal forests. From 2019, this species gradually declined until completely disappearing by the end of 2020.

Materials examined: —18ECS1-2 (2 to 8)