Developmental morphology of Gigartina pistillata (Gigartinaceae, Rhodophyta)

Abstract The vegetative and reproductive development of the type species of the marine red alga Gigartina. G. pistillata (S.G. Gmelin) Stackhouse (Gigartinaceae, Rhodophyta), is described based on material from Brittany, France. Gigartina pistillata possesses a loose primary network of medullary filaments in which every cell is normally connected to each of its neighbouring cells by a single primary or secondary pit connection. Secondary filaments up to three cells long fill the gaps created as the network expands and link terminally to cells below by secondary pit connections. The procarp is derived by successive concavo-convex divisions of a surface cell that is homologous to the apical initial of a vegetative cortical filament, and consists of an inner cortical supporting cell bearing a curved, 3-celled carpogonial branch and a single, lateral cortical filament. After presumed fertilization, the carpogonium fuses with the auxiliary cell effecting transfer of the zygotic nucleus. Small diploid nuclei in...