PILAYELLA LITTORALIS F. RUPINCOLA FROM WASHINGTON: THE LIFE HISTORY IN CULTURE1

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Abstract
The life history of Pilayella littoralis f. rupincola from Washington was studied in culture using supplemented natural seawater media and various temperature, photoperiod, and light intensity regimes. Plants in nature exhibited characteristics typical for f. rupincola. Plants in culture, however, did not show the same morphological features, although they had a life history presumed typical for f. rupincola. Successive generations of plants in culture formed only unilocular sporangia. On the basis of morphological characters and the life history, Kylin elevated f. rupincola to species rank. Variation in morphology of both field collected and cultured specimens makes such recognition untenable. It is concluded that the type of life history alone is not adequate justification for the recognition of P. rupincola as a species, but the stability of the life history in various culture environments appears to warrant continued recognition of this taxon as a distinct form of P. littoralis, as originally proposed by J. E. Areschoug.