THE TETRASPOROPHYTE OF SCINAIA JAPONICA SETCHELL (NEMALIALES-RHODOPHYTA)

Abstract

On the basis of cytological investigations of SvEDELIUS (1915) on Scinaiafurcellata and of K YLIN (1916) on Nemalion multijidum which showed that meiosis occurred in the carpogonium immediately following fertilization, the majority of Nemaliales in which tetrasporophytes are unknown have been considered to be haplobiontic. Recently, this was shown to be uncorrect by MAGNE (196la, 196lb, 1964a, 1964b), who demon-strated cytologically that Lemanea, Nemalion and Scinaia produce carpospores and carpo-spore germlings which are diploid. BOILLOT (1968), working on the life history of Scinaia furcellata in culture, has confirmed MAGNE's cytological results. She has found that carpospore germlings develop into dwarf, filamentous tetrasporophytes with which macroscopic gametophytes alternate. In recent years, corroborative studies have been made by VON STOSCH (1965) in Liagora farinosa, by FRIES (1967) in Nemalion multi-fidum, by UMEZAKI (1967) in N. vermiculare, and by RAMUS (1969) in Pseudogloeophloea confusa. Thus, recent studies have demonstrated that some Nemaliales in which tetras-porophyte was not known possess an independent tetrasporophyte. I NOH (194 7), who cultured carpospores of Scinaia japonica to an early stage of germ-lings, has supposed that the germlings must directly develop into gametophytes. The present work was undertaken to study the life history of Scinaia japonica SET-CHELL (Chaetangiaceae, Nemaliales) in which sporophyte is unknown. Material and Methods Scinaia japonica SETCHELL grows on sandy bottom from a little below the low tide level to a depth of about 10 meters and it becomes fertile early in April at Shirahama, Wakayama Prefecture from where plants that were cultured were obtained. A few cystocarpic plants were collected on April 3, 1968 at Shirahama and soon brought to the Department of Fisheries, Kyoto University at Maizuru, where the cul-ture work was carried out. I) Contributions from the Seto Marine Biological Laboratory, No.549.