Life history of two species Bryopsis from the Straits of Messina (Italy).

Observations on cultured specimens of Bryopsis J.V. Lamouroux, a genus with many species of uncertain taxonomic status, carried out in order to obtain a better understanding of the life histories of Bryopsidaceae, are presented. In particular, the life histories of B. hypnoides J.V. Lamouroux and B. corymbosa J. Agardh showed by two populations collected in the Straits of Messina (the Mediterranean Sea) and grown in laboratory conditions, are here outlined. In both species the life history is diplobiontic and strongly heteromorphic. Gametophytes are either monoecious (in B. hypnoides) or dioecious (in B. corymbosa). The germling zygotes form microscopic sporophytes, which, after a period of dormancy from some months to a year or more, produce holocarpically stephanokontan zoospores. Both gametophytes and sporophytes are able to reproduce vegetatively. A life history of this kind is typical for the genus Bryopsis. This is the first report on the life history of B. corymbosa, a taxon described on Mediterranean specimens.