The Life History of Porphyra tanegashimensis (Rhodophyta, Bangiales) in Laboratory Culture.

The life history of the red alga Porphyra tanegashimensis SHINMURA collected from Okinawa Island, southern Japan, was completed in laboratory culture. The culture was started using the free-living Conchocelis thalli of this species. Fragments of Conchocelis filaments were scattered on oyster shells and they regenerated branchlets. The branchlets began to penetrate into the shells and developed newly to Conchocelis thalli. Growth morphology and growth degree closely resembled to those of the other species of Porphyra such as P. yezoensis. The colour of the Conchocelis thalli, densely growing in the shells, was generally reddish purple. The suitable growth temperature of the Conchocelis thalli was seemed to be 25℃ which was higher than that of other species of cultivated Porphyra. Conchosporangia were formed under the temperatures of 25～30℃. When the Conchocelis thalli with conchosporangia transferred to lower temperatures of 20～22℃ , they became mature and liberated conchospores. Liberated conchospores become spherical, measuring 11-14 μm in diameter, and germinated into leafy thalli. Developed leafy thalli were divided into several lacerate blades having microscopic dentides along the margins. After 65 days culture, they attained to 12 cm in length and formed antheridial and cystocarpic cells. The chromosome number of this alga was conuted to be three in vegetative cell and antheridium, and to be six in carpospore germling, Conchocelis filament and immature conchosporangium