Halymenia pseudofloresii Collins & M.Howe

Resendiz, María Luisa Núñez, Dreckmann, Kurt M., Sentíes, Abel, Wynne, Michael J. & Tejera, Hilda León, 2019, Marine red algae (Rhodophyta) of economic use in the algal drifts from the Yucatan Peninsula, Mexico, Phytotaxa 387 (3), pp. 219-240 : 234

Halymenia pseudofloresii Collins & M.Howe

Thallus membranous, mucilaginous, laminar, extended, purple-red, 25–36 cm in length, flattened in cross section, 285–310 μm in diameter. Main axes branching irregularly; branches with the appearance of ribbon strips, with margins completely covered by proliferations of sizes and variable diameters, arranged alternately opposite ( Fig. 59 ). Multiaxial organization with a filamentous medulla and a pseudoparenchymatous cortex ( Fig. 60 ). Medulla composed of several filaments loosely arranged in mucilaginous gel, 6–12 μm in diameter. Cortex composed of two layers of rounded cells, 10–18 μm in diameter. Tetrasporangia spherical, 15–20 μm in diameter, cruciately divided, scattered among the cortical cells ( Fig. 61 ).

Taxonomic comment: According to Schneider et al. (2010), from molecular data, Halymenia pseudofloresii is the only species distributed in the American Atlantic coasts. Its sister species, H. floresii , which has been previously recorded for Yucatan Peninsula ( Godínez-Ortega et al. 2008), appears to be restricted to Europe ( Schneider et al. 2010, Wynne 2017).

Figures

FIGURES 51–64. 51–53. Gracilaria usneoides. 51. Habit. Scale bar = 3 cm. 52. Medullary and cortical cells. Scale bar = 260 μm. 53. Mature cystocarp. Scale bar = 420 μm. 54–55. Gracilariopsis tenuifrons. 54. Habit. Scale bar = 4 cm. 55. Medullary and cortical cells. Scale bar = 170 μm. 56–58. Codiophyllum sp. 56. Habit. Scale bar = 4 cm. 57. Apices with small ligules. Scale bar = 5 cm. 58. Medullary filaments and cortical cells. Scale bar = 120 μm. 59–61. Halymenia pseudofloresii. 59. Habit. Scale bar = 4 cm. 60. Medullary filaments and cortical cells. Scale bar = 460 μm. 61. Tetrasporangium in cortex. Scale bar = 40 μm. 62–64. Botryocladia occidentalis. 62. Habit. Scale bar = 4 cm. 63. Medullary and cortical cells in cylindrical axes. Scale bar = 300 μm. 64. Medullary and cortical cells in globular branches. Scale bar = 150 μm.