Porphyra sp. (Bangiales, Rhodophyta): reproduction and life form

The reproductive pattern of Porphyra sp. was observed in laboratory culture. The thalli obtained from both natural populations and from cultures were monostromatic and reniform, obovate to linear-oblanceolate. Under the different culture conditions, no differentiation of sexual cells, spermatia or carpogonia, was observed; propagation occurred by archeospore formation (sensu Magne, 1991), with bipolar germination. Thirty successive generations have been obtained in culture, at temperatures of 12 °C and 15 °C, and each time a laminar gametophytic thallus was produced. It is concluded that Porphyra sp. has a strictly asexual reproductive pattern. This is interpreted as a reproductive adaptation to its epiphytic life form.