Mary J. Holmes, Juliet Brodie
Phenology and the life history in culture of Porphyra leucosticta (Bangiales, Rhodophyta) from Britain
A seasonal study of field-collected individuals of Porphyra leucosticta at Sidmouth, Devon, UK showed that the blade phase was present from April to September 2001. Specimens of P. leucosticta were epiphytic on Fucus serratus, Mastocarpus stellatus, Chondrus crispus and Osmundea pinnatifida, and epizoic on Mytilus edulis, often found growing in layers on the host. Field material was monoecious, with male and female gametangia in separate sori, but intermixed along the margins of thalli. Mean size (wet mass and dry mass, length and width) was lowest in April and greatest in July. All spores released in culture from field-collected material developed into conchocelis, except one individual, which released archeospores that developed into blades. The life history was completed in culture at both 15°C/long days (16:8 h light:dark cycle) and 15°C/short days (8:16 h light:dark cycle). A protothallus developed directly on the vegetative conchocelis filament by divisions of one of the vegetative cells and either detached and dropped to the bottom of the culture dish or remained as part of the conchocelis. The protothallus produced either archeosporangia or male and female gametangia or both. Chromosome numbers of n=3 in male gametangia, 2n=6 in zygotosporangia and 2n=6 in the conchocelis phase suggest that fertilisation had taken place.
Botanica Marina, Walter de Gruyter
Print ISSN: 0006-8055
Volume: 48, 07/2005
Pages: 218 - 230
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