Morphological reassessment and molecular assessment of Sargassum (Fucales: Phaeophyceae) species from the Gulf of California, Mexico Author Andrade-Sorcia, Gabriela Programa de Investigación en Botánica Marina, Departamento de Biología Marina, Universidad Autónoma de Baja California Sur, carretera al sur 5.5 km, P. C.: 23080, 19 - B, La Paz, Baja California Sur, México. Author Riosmena-Rodríguez, Rafael Programa de Investigación en Botánica Marina, Departamento de Biología Marina, Universidad Autónoma de Baja California Sur, carretera al sur 5.5 km, P. C.: 23080, 19 - B, La Paz, Baja California Sur, México. Author Muñiz-Salazar, Raquel Universidad Autónoma de Baja California, Blvd. Zertuche y Blvd. de los Lagos s / n. Fracc. Valle Dorado. C. P. 22890, Ensenada, Baja California, México. Author López-Vivas, Juan Manuel Programa de Investigación en Botánica Marina, Departamento de Biología Marina, Universidad Autónoma de Baja California Sur, carretera al sur 5.5 km, P. C.: 23080, 19 - B, La Paz, Baja California Sur, México. Author Boo, Ga Hun Department of Biology, Chungnam National University, Daejeon 305 - 764, Korea. Author Lee, Kyung Min Universidad Autónoma de Baja California, Blvd. Zertuche y Blvd. de los Lagos s / n. Fracc. Valle Dorado. C. P. 22890, Ensenada, Baja California, México. Author Boo, Sung Min Universidad Autónoma de Baja California, Blvd. Zertuche y Blvd. de los Lagos s / n. Fracc. Valle Dorado. C. P. 22890, Ensenada, Baja California, México. text Phytotaxa 2014 2014-10-24 183 4 201 223 http://dx.doi.org/10.11646/phytotaxa.183.4.1 journal article 10.11646/phytotaxa.183.4.1 1179-3163 5150054 Sargassum sinicola Setchell & Gardner (1924 :.736, pl. 20, fig. 73) ( Figs. 3I–J ). Heterotypic synonyms: Sargassum cylindrocarpum Setchell & Gardner (1924: 738 , pl. 21, fig. 77); Sargassum polyacanthum f. americanum Setchell & Gardner (1924: 736) ; Sargassum paniculatum Setchell & Gardner (1924: 740) ; Sargassum californicum (Grunow 1916: 173) Setchell (1937: 129) . Type material:— MEXICO . Eureka, near La Paz , Baja California Sur . Marchant no. 20 . Description: —Thalli attached underneath by a coarse holdfast with short, thick protuberances. Stipe cylindrical and smooth. Blades linear-lanceolate, with acute serrated margins. Costate (nerve or midrib) percurrent and conspicuous, evident cryptostomata sparse and inconspicuous. Numerous vesicles present, mostly borne near the base of the pedicel, vesicles spherical, smooth, 3–5 mm in diameter. Pedicels terete, their length equaling the vesicles’ diameter. Receptacles forked, with some thorns, with intermixed antheridial and oogonial receptacles growing in a bunch, receptacles cylindrical with acuminate apices (not spinose), growing in an axillary fashion with vesicles. Thalli with smooth axes, smooth branches and branchlets. Thalli reaching up to 60 cm long. Habitat:— Growing on calcareous surfaces (shells) and rocky beds together with S . horridum , S . lapazeanum and S . johnstonii . Thalli grew at temperatures ranging from 8 to 28 °C. Current distribution:— Sonora ( Turner Island , Pond Island-Guaymas; Kino, Punta Peñasco); Baja California Sur ( Concepcion Bay , Eureka, La Paz , San Pedro Martir Island , el Tesoro ), Baja California ( El Huerfanito ) . Remarks:— Sargassum sinicola was first described by Setchell & Gardner (1924) , who noted the absence of a holdfast in the sample. Dawson (1944) reported that the type specimen of S . sinicola was a fragment of the upper reproductive part and only showed the characteristics of that portion of the plant; although this fragment showed all the characteristics described by Setchell & Gardner (1924) . Dawson (1944) described the holdfast of this species and recommended combining characteristics from different structures for identification because the holdfast does not differ sufficiently between species to function as a discriminant characteristic. A description of S. sinicola was not included in Dawson’s work since the conspecificity of S. camouii and S. sinicola was assumed. In this species, a discriminant characteristic is the shape of the vesicle, which is spherical and smooth. It also has a pedicel that is shorter than the sphere’s diameter, growing over the pedicel of the blade.