Sargassum polycystum C.Agardh

Systema algarum: 304 (Agardh 1824).

Sargassum myriocystum sensu Santiañez & Trono (2013), non Sargassum myriocystum J.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 cm long, holdfast discoid. Main axis terete, warty, short, usually to 5 mm long (rarely to 18 mm long), bearing several secondary axes, some of which are modified into stoloniferous holdfast (Fig. 5 A-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 mm long, 13 mm wide, 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 mm long, 6 mm wide, 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 mm long and 1.5 mm wide, 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 mm long, 1 mm at the widest (Fig. 5F); male receptacles smooth, filiform, to 5 mm long, cylindrical in cross-section, to 0.5 mm in diameter (Fig. 5G).