Morphology and taxonomy of Adenocystis longissima (Skottsberg) stat. nov. (Phaeophyceae) from subantarctic South America

摘要

Adenocystis utricularis f. longissima, described by Skottsberg (1921), is a little-known brown alga with a restricted austral distribution (South American regions of Patagonia, Tierra del Fuego, the Falkland Islands and South Georgia). It has not been re-examined after its description. We have studied field thalli and laboratory cultures of this alga from southernmost South America and compared them to those of the typical form of A. utricularis from the same region. Significant differences were found between the taxa in morphology of both adult field thalli and juvenile stages in culture. In nature, both taxa occurred in mixed populations without intermediates. Based on these results, we propose to elevate A. utricularis f. longissima to species rank. Syn-type material of A. utricularis f. longissima from Uppa-sala University (UPS) was examined and a lectotype was designated. Adenocystis includes three species: A. longissima, A. rimosa and A. utricularis.