Vegetative and reproductive morphology of Dudresnaya canariensis sp. nov. (Dumontiaceae, Rhodophyta)

Abstract

The marine red alga Dudresnaya canariensis sp. nov. (Dumontiaceae, Gigartinales) from the Canary Islands is described. Gametophytes are terete and radially branched, young branches are nonannulate, outer cortical cells are cylindrical, axial cells contain hexagonal crystals, cells of primary axes are conspicuous, and rhizoids reach 95 μm in diameter. Spermatangial mother cells occur in corymbose clusters on the outer cortex, and carpogonial and auxiliary-cell filaments, both of which lack a thick mucilage coat, arise in the mid-cortex. Carpogonial filaments are reflexed, the carpogonium and trichogyne differentiating after final oblique division. The gonimoblast initials do not recurve around the auxiliary-cell filament, and the cystocarps are distinctly cleft. Tetrasporophytes are unknown. The only unique feature of D. canariensis is the arrangement of its spermatangia in corymbose terminal and subterminal fascicles, a feature unreported in the few species of Dudresnaya where male gametophytes are known. However, D. canariensis differs from the other Dudresnaya species by a unique combination of significant attributes. It is postulated that the Australian D. capricornica and the Japanese D. kuroshioensis are the closest relatives of the new species.