Osmundea lata (M. Howe & W.R. Taylor) comb. nov. (Ceramiales, Rhodophyta) from the Brazilian south-eastern continental shelf

Specimens of Laurencia lata were dredged from the south-eastern Brazilian continental shelf near Cabo Frio (off the state of Rio de Janeiro) from a depth of 60 m, growing as epiphytes on the rhizoids if Laminaria abyssalis. Detailed examination of the vegetative and reproductive morphology of these specimens revealed anatomical characteristics belonging to the recently resurrected genus Osmundea. Such features include two periaxial cells per vegetative axial segment, spermatangial branches arising directly from apical and epidermal cells in the apical pit of branchlets (filament type), and tetrasporangia cut off from random epidermal cells. On the basis of these features. Osmundea lata (M. Howe & W.R. Taylor) Yoneshigue-Valentin, M.T. Fujii & Gurgel is proposed as a new combination for Laurencia lata. We present detailed observations of the vegetative and reproductive morphology of O. lata, and compare it with related species; its geographical distribution is also discussed