THE MORPHOLOGY OF SCINAIA-COTTONII SETCHELL (GALAXAURACEAE, RHODOPHYTA)

The little-known red alga Scinaia cottonii Setchell from deep water wa s collected in abundance offshore from Cape Shionomisaki, in the middl e Pacific Honshu, Japan. Its morphology was examined in detail and com pared with that of other members of the genus Scinaia. The female repr oductive structure, monosporangia, and the development of the carpospo rophyte are newly reported for this species. Carpogonial branches are three-celled with an elongate trichogyne. The hypogynous cell produces one one-celled and one two-celled lateral sterile branches. The basal cell of carpogonial branches gives rise to pericarpial filaments befo re fertilization. Several gonimoblast initials arise terminally, subte rminally or laterally from the fertilized carpogonium. Young gonimobla st filaments are all free. Mature gonimoblasts consist of a pseudopare nchymatous inner part and filamentous outer part. All, or the upper se veral, cells of the gonimoblast filaments become carposporangia. The l ower gonimoblast cells, the carpogonium, the hypogynous cell and the b asal cell of carpogonial branches form a fusion cell. Mature cystocarp s reach 482 mu m in diameter.