本文對臺灣之新記錄馬尾藻 Sargassum alternato-pinnatum Yamada 進行闡述。標本採集於蘭嶼海岸淺潮池中。該種具有以下之特徵：一、小型盤狀固著器；二、主軸呈圓柱形；三、刺棘生於藻枝表面；四、藻葉一至三次分叉；五、氣囊為球形且尖端鈍圓；六、生殖托與藻葉或似氣囊結構同柄混生；七、雌雄生殖巢散生於同一生殖托。本文提供繪圖及相片作為鑑定該種之依據。

This report describes Sargassum alternato-pinnatum Yamada as a newly recorded species in Taiwan. The specimens for this study were collected from a shallow tidepool in Lan-yu, Taiwan. This species is characterized by the following features: (1) small discoid holdfast, (2) terete primary branches, (3) sharp spines arising from surface of branches, (4) leaves that furcate 1–3 times, (5) spherical vesicles around the apex, (6) pseudozygocarpic receptacles with leaves or vesicle-like tissues, and
(7) male and female conceptacles scattered within the receptacles. In this report, we also present a line drawing and photographs
for the identification of S. alternato-pinnatum.