| Abstract: | The life history of Spermatochnus paradoxus (Roth) Kütz. isolated from the Mediterranean Sea was studied in culture. Meiospores develop to a microscopic stage (microthallus) which at 20°C perpetuates asexually by plurilocular sporangia and formation of new microthalli. At 9°C microthalli act as homothallic gametophytes. Fusion of isogametes results in a diploid microthallus which, after differentiation of an apical cell, leads back to Spermatochnus plants. In addition, gametes develop without fusion to form haploid macrothalli, the further fate of which has not been determined. Chromosome numbers alternate between n = 20 ± 2 in the microthalli and 2n = 41 ± 4 in macrothalli. |
