The morphology, reproduction and small-subunit rRNA gene sequence of Cephalocystis (Rhodymeniaceae, Rhodophyta), a new genus based on Cordylecladia furcellata J. Agardh from Australia

Abstract

The southeastern Australian endemic species Cordylecladia furcellata J. Agardh differs in habit, minor anatomical, and significant small-subunit rRNA-sequence details from the European type species of the genus, Cordylecladia erecta (Greville) J. Agardh. Particularly conspicuous in C. furcellata are the colourless, apical, pod-like structures to which all reproductive stages are confined, in contrast to C. erecta in which spermatangia and tetrasporangia occur in linear, subterminal swellings and cystocarps form in dense aggregates along otherwise unmodified axes. The new genus Cephalocystis is proposed to include, as type species, C. furcellata (J. Agardh) comb. nov., plus an undescribed New South Wales species, C. leucobotrys sp. nov. The latter differs mainly in the position of the cystocarps, which occur in subterminal clusters on major axes rather than in terminal hyaline pods. Given the similarity of habit, vegetative anatomy and cystocarp position in the European type species of Cordylecladia and Cephalocystis leucobotrys from eastern Australia, the molecular data indicating substantial phylogenetic distance between the European and Australian species are accorded major taxonomic weight.