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Porphyra from the Caribbean coast of Venezuela, previously referred to P. umbilicalis (L.) J. Agardh, was found to be conspecific with P. spiralis var. amplifolia Oliveira Filho et Coll which was described from Brazil. Laboratory studies have produced a functional life history from the blade to filamentous conchocelis phase and back to the blade. Cross-gradient light-temperature culture was utilized to investigate the effects of photon fluence rate, temperature and daylength on conchocelis growth and reproduction. Both conchospore formation and release occurred only in a daylength of 12 h or less, with the former restricted to 20 -30 °C, and the latter to 15 -22 °C. Results of these investigations were used to explain the seasonal periodicity of growth and reproduction of this species observed in a field study on Isla de Margarita.

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