Occurrence of polynucleate spores of the crustose coralline alga Lithophyllum yessoense (Corallinales, Rhodophyceae): growth and survival

Nonnucleate, uninucleate. binucleate, trinucleate and tetranucleate spores were found in sporophytes of Lithophyllum yes soense. The formation of poly nucleate spores was caused mainly by the irregular distribution of nuclei i n tetrasporangia. Both nuclei in a binucleate spore took part in developmen t, suggesting that polynucleate spores grow into chimaeric crusts. The rela tive growth rate was higher in sporelings developed from trinucleate and te tranucleate spores (c. 12% d(-1)) than from uninucleate and binucleate spor es (c. 5% d(-1)). However, the survival rates of sporelings developed from trinucleate and tetranucleate spores were less than half of those developed from uninucleate and binucleate spores. Polynucleate spores frequently occ urred at low water temperature, especially at less than 12.1 degreesC. indi cating that successful reproduction via spores would be limited by low wate r temperature in winter, although this is when spore production is highest in southwestern Hokkaido.