Sargassum aquifolium (Turner) C.Agardh Fucus aquifolius Turner, Fuci sive plantarum fucorum generi a botanicis ascriptarum icones descriptiones et historia: 111 (Turner 1807). Sargassum kushimotense sensu Trono (1992, 1997); Santiañez & Trono (2013), non Sargassum kushimotense Yendo. TYPE LOCALITY. — Indonesia. Sunda Strait (Silva et al. 1996). SPECIMENS EXAMINED. — Philippines. Ilocos Sur, San Esteban, Apatot, 26.IX.2018, leg. W.J.E. Santiañez (MSI [MSI29154]); La Union, Balaoan, Almeida, 27.IX.2018, leg. W.J.E. Santiañez (MSI [MSI29195]); La Union, Balaoan, Paraoir, 27.IX.2018, leg. W.J.E. Santiañez (MSI [MSI29204]). DISTRIBUTION IN NORTHWESTERN LUZON. — Ilocos Sur, La Union, and Pangasinan (Fig. 1). DESCRIPTION Thallus golden brown when fresh (Fig. 3A), drying dark brown, to 42 cm long, attached to the substrate by a conical to discoid holdfast (Fig. 3B, C). Main axes smooth, slightly compressed, short, to 3 mm long, giving rise to several compressed secondary axes, 2.5 mm wide (Fig. 3C). Blades linear-lanceolate to linear-oblanceolate, narrowed towards blunt or acute apices, mostly less than 36 mm long, 8 mm wide; margins serrate-dentate; stalk short, base asymmetrical; midrib apparent, slightly elevated, fading near the tips; cryptostomata prominent, elevated, scattered but tending to be arranged in rows in narrow blades (Fig. 3B, D). Vesicles large, ovoid to obovoid, 5 mm wide, 7 mm long; tips rounded to pointed, some mucronate; stalks compressed, winged to foliaceous, often as long as vesicles (Fig. 3D). Young receptacles densely clustered, short, compressed to slightly flattened (some somewhat triquetrate, others twisted), often with sharp teeth.

Published as part of Santiañez, Wilfred John E., Lastimoso, John Michael L., Hoshino, Masakazu, Villafuerte, Brix Nester Q., Kogame, Kazuhiro & Gavino C. Trono, Jr, 2023, Molecular-assisted taxonomic study on the Sargassum C. Agardh (Fucales, Phaeophyceae) in northwestern Luzon, Philippines, pp. 127-142 in Cryptogamie, Algologie 20 (7) on page 132, DOI: 10.5252/cryptogamie-algologie2023v44a7, http://zenodo.org/record/10020969