Sargassum myriocystum sensu Santiañez & Trono (2013) Sargassum myriocystum J.Agardh. Molecular-assisted taxonomic study on the Sargassum C. Agardh (Fucales, Phaeophyceae) in northwestern Luzon, Philippines Santiañez, Wilfred John E. Lastimoso, John Michael L. Hoshino, Masakazu Villafuerte, Brix Nester Q. Kogame, Kazuhiro Gavino C. Trono, Jr Cryptogamie, Algologie 2023 2023-10-18 20 7 127 142 C. Agardh C. Agardh [278,629,215,242] Phaeophyceae Sargassaceae Sargassum Chromista Fucales 9 134 Ochrophyta species polycystum   Systema algarum: 304 ( Agardh 1824).   Sargassum myriocystum sensu Santiañez & Trono (2013), non  Sargassum myriocystumJ.Agardh.     TYPE  LOCALITY. —  Indonesia. Sunda Strait ( Silva et al.1996: 694).  SPECIMENS EXAMINED. —   Philippines. Pangasinan, Bolinao, Dos Hermanos,  9.III.2019, leg. A.C. Calaguing( MSI[ MSI29138, MSI29139]);  Pangasinan, Bolinao, Malilnep,  9.III.2019, leg. A.C. Calaguing( MSI[ MSI29140]);  Ilocos Norte, Burgos, Bayog,  25.IX.2018, leg. W.J.E. Santiañez( MSI[ MSI29141, MSI29142, MSI29143, MSI29144, MSI29148]);  La Union, Balaoan, Almeida,  27.IX.2018, leg. W.J.E. Santiañez( MSI[ MSI29197]).   DISTRIBUTION IN NORTHWESTERN LUZON. — Ilocos Norte, Ilocos Sur, La Union, Pangasinan( Fig. 1).    DESCRIPTION Thallus golden (when fresh) to dark brown (when dried) in color, to 57 cmlong, holdfast discoid. Main axis terete, warty, short, usually to 5 mmlong (rarely to 18 mmlong), bearing several secondary axes, some of which are modified into stoloniferous holdfast ( Fig. 5A-C). Secondary axes with numerous short protuberances, these either densely aggregated or sparsely distributed throughout the surface ( Fig. 5A, D); secondary axes of some specimens smooth ( Fig. 5E). Blades on vegetative branches large, to 60 mmlong, 13 mmwide, oblong to oblanceolate, base asymmetrical, margin serrate-dentate, apices acute to rounded, cryptostomata elevated and scattered, midrib distinct, disappearing before the tip; those in fertile branches considerably smaller, less than 15 mmlong, 6 mmwide, obovate, some oblong to somewhat oblanceolate, base asymmetrical, margin serrate dentate, midrib usually not apparent, but only occur in the basal 1/3 of the blades when present, apices rounded to obtuse. Vesicles small, generally less than 2 mmlong and 1.5 mmwide, numerous, spherical to ovoid, often with a short and thin or foliaceous mucro, subtended by short (sometimes as long as vesicles) and thin stalks ( Fig. 5D, E). Plant dioecious ( Fig. 5F, G), receptacles closely associated with vesicles and/or blades (zygocarpic), racemosely arranged; female receptacles toothed, compressed (rarely triquetrous) to flattened towards the tip, sometimes somewhat twisted, generally less than 2.5 mmlong, 1 mmat the widest ( Fig. 5F); male receptacles smooth, filiform, to 5 mmlong, cylindrical in cross-section, to 0.5 mmin diameter ( Fig. 5G). 4428726310 2019-03-09 MSI A. C. Calaguing Philippines Dos Hermanos Bolinao 9 134 MSI29138, MSI29139 1 Pangasinan 4428726305 2019-03-09 MSI A. C. Calaguing Malilnep Bolinao 9 134 MSI29140 1 Pangasinan 4428726311 2018-09-25 MSI W. J. E. Santianez Bayog Burgos 9 134 MSI29141, MSI29142, MSI29143, MSI29144, MSI29148 1 Ilocos Norte 4428726313 2018-09-27 MSI W. J. E. Santianez Almeida Balaoan 9 134 MSI29197 1 La Union