Two new distinctive Peyssonnelia species are described from deepwater habitats in southwestern Puerto Rico. Peyssonnelia iridescens possesses a distinctive bluish iridescent fringe and forms loosely adherent blades up to 6.0 cm across. The crusts possess a Peyssonnelia atropurpurea-type vegetative organization. Tetrasporangia are cut off distally from apical perithallial cells and measure up to 53 mm wide 3 135 mm long. Carposporangia measure 25–30 mm in their largest dimension and are formed in elongate nemathecia. Peyssonnelia gigaspora is variously coloured, tan to reddish, with obvious radial striations and reddish spots when living. The crusts are closely appressed to the substratum and normally measure up to 130 mm in thickness, but are occasionally 200 mm thick and possess the Peyssonnelia rubra-type vegetative organization. Tetrasporangia are ovate and extremely large, measuring up to 100 mm wide 3 250 mm long, and differentiate from the proximal paraphysal cell, thus being situated in an intercalary position.
Algae (Macro, Turf and Crustose Coralline)