Sargassum lapazeanum Setchell & Gardner (1924: 733

Andrade-Sorcia, Gabriela, Riosmena-Rodríguez, Rafael, Muñiz-Salazar, Raquel, López-Vivas, Juan Manuel, Boo, Ga Hun, Lee, Kyung Min & Boo, Sung Min, 2014, Morphological reassessment and molecular assessment of Sargassum (Fucales: Phaeophyceae) species from the Gulf of California, Mexico, Phytotaxa 183 (4), pp. 201-223 : 210-211

Sargassum lapazeanum Setchell & Gardner (1924: 733 , pl. 20, fig. 74) ( Figs. 3F–H ).

Heterotypic synonyms: Sargassum bryantii Setchell & Gardner (1924: 733 , pl. 21, fig. 8); Sargassum insulare Setchell & Gardner (1924: 735 , pl. 20, figs. 67, 68; pl. 21, fig. 78); Sargassum macdougalii Dawson (1944: 245 , pl. 35, figs. 1–8; pl. 36, figs. 1–7; pl. 37, figs. 27–30), syn. nov.; Sargassum sonorense Dawson (1960: 36) , syn. nov.; Sargassum asymmetricum Dawson (1944: 244 , pl. 36, figs. 8–18), nom. illeg.

Type:— MEXICO. La Paz, Baja California Sur. Marchant no. 21 .

Description: —Thalli arising from a solid parenchymatous holdfast initially discoid, becoming conical or hapteroid. Stipe and branches terete and smooth, giving rise to numerous long, slender primary branches with or without secondary branches. Leaves 0.5–2.5 cm long, asymmetrical, wider towards the apices, with short pedicels. Apical side of the blade crown/shaped (not flat), and some blades are twisted on the basal half of the upper margin, which is smooth and concave. The remainder of the blade is sharply dentate and the costate is inconspicuous. Cryptostomata present and conspicuous, vesicles scattered among ellipsoidal receptacles. Bladders mostly blade-shaped and crowned by the remnants of the blade, forming a crest. Receptacles forked with some thorns as ornamentations, with intermixed antheridial and oogonial receptacles growing in a bunch on the same thallus. Thalli 10 cm to 1.5 m in length.

Habitat:— On rocks in the intertidal to subtidal zone (3 m depth), in beds containing S. horridum , S. sinicola and S. johnstonii .

Current distribution:— Sonora (Guaymas, Tortuga Island, San Marcos Island, Turner’s Island, San Francisquito Bay, Puerto Libertad, Puerto Refugio, Poindexter, Punta Peñasco, Tepoca Bay, Punta San Pedro, Tiburon Island, Patos Island, San Pedro Nolasco Island) on rocky coasts; Baja California (Puertecitos, San Luis Gonzaga, Gonzaga Bay, Mejia Island, Punta Bufeo, La Gringa, Smith Island, De Los Angeles Bay, la Partida Island, Angel de la Guarda Island, La Ventana (on rocky coasts); Baja California Sur (Concepción Bay, Coronado Island, Danzante Island, La Paz Bay, La Partida Island) on rocky coasts and calcareous surfaces.

Remarks:— Sargassum lapazeanum was described by Setchell & Gardner (1924) using a complete specimen. Its description was considered as primary description for the Lapazeanum group by Dawson (1944) and Sargassum section Lapazeanum by Norris (2010). For the present study, S. macdougalii and S. sonorense were considered synonyms of S. lapazeanum . We collected complete thalli for morphological characterization of the Lapazeanum group. Following morphological revaluation, we identified many characteristics that overlapped between species’ descriptions, making identification difficult. The descriptions were similar and we were unable to identify any discriminant characteristics to segregate these species. All observed thalli showed the characteristics described by Setchell & Gardner (1924), as well as characteristics used in other studies. This species was only recorded in La Paz, Baja California Sur, by Setchell & Gardner (1924), later Dawson (1944) recorded it from Sonora. Norris (2010) recorded this species along the peninsula of Baja California (Baja California and Baja California Sur). We found this species along the coastline of the Gulf of California, with a high morphological variability, as reported by Andrade-Sorcia et al. (2008).

Figures

FIGURE 3. Morphology of Sargassum johnstonii, S. lapazeanum and S. sinicola. A. Habit of S. johnstonii. B, E. Blades (arrow) and vesicles (arrow heads) above the branch. D. Discoid holdfast and smooth branches. F.Habit of S. lapazeanum. G. Bladders (arrow) and blades growing in clusters. H. Discoid holdfast. I. Habit of S. sinicola. J. Leaves and vesicles (arrow) growing in clusters. Scale bars = 1 cm.