REVIEW OF RECENT TAXONOMIC CONCEPTS AND DEVELOPMENTS IN THE GRACILARIACEAE (RHODOPHYTA)

Despite much effort in the past decade to resolve the taxonomy of algae in the Gracilariaceae, the family remains problematic. Generic concepts have become equivocal as their diagnostic reproductive features have been reported as mixed in single species. Species concepts are often also uncertain since the full phenotypic range of a species is seldom known or appreciated. This paper reviews some of the recent taxonomic controversy from the viewpoints of morphology and molecular biology. As more observations are made, features like spermatangial configuration and mode of gonimoblast nutrition, once considered characteristic of genera and subgenera, are emerging as a continuum of types that may vary within species. Culture studies to establish the reproductive anatomy of a life history and to test crossabilities are invaluable to species concepts but also may yield false results owing to clonal variability and intraspecific sterility. Characteristics of DNA have been effective in clarifying some aspects of gracilariacean taxonomy and phylogeny, and may be able to resolve the major inconsistencies if more widely applied.