Sphacelariales (Phaeophyceae) of the World, a New Synthesis

Algae > Volume 8(2); 1993 > Article

Algae 1993;8(2): 145-160.

Willem F. Prud'homme van Reine

Research Institute Rijksherbarium/Hortus Botanicus, Leiden University

ABSTRACT

In the brown algal order Sphacelariales (sensu stricto) usually three families are included: Cladostephaceae, Sphacelariaceae, and Stypocaulaceae. About the status of the family Choristocarpaceae, currently often also incorporated in this order, the taxonomic situation is not clear yet. The three families of Sphacelariales s.s. are well founded and sufficiently different form each other. In the Cladostephaceae only one species is incorporated: Cladostephus spongiosus. The family Sphacelariaceae contains in the genus Sphacelaria the largest number of species of all these families. The family Stypocaulaceae is richest in genera, but all genera only contain a small number of species. The problems of the delimitation of genera in the order Sphacelariales s.s. will be reviewed, resulting in a descriptions of new supraspecific taxa in Sphacelaria and a proposal to reinstate the genus Stypocaulon. In the Choristocarpaceae currently five species in four genera are distinguished. In the present synthesis this family is incorporated as belonging to the order Sphacelariales sensu lato. All species and higher taxa belonging to this order are discussed in some detail in the present paper. The geographic distribution of most taxa will be discussed as well. Biodiversity in Sphacelariales is most prominent in temperate areas. Both in tropical seas and in very cold environments the number of taxa of Shpacelariales in very small. In tropical areas only species of Sphacelaria subgenus Propagulifera occur, usually members of the section Furcigerae as well as of the section Tribuloides. Other sections of this subgenus, as well as other subgenera in Sphacelaria, are usually confined to temperate areas, although some species may also occur in Arctic waters (subgenus Pseudochaetopteris) or in (sub-) Antarctic waters (Sphacelaria affinis, S. bornetii). The representatives of the other families are also mainly found in temperate waters, only the monotypic genus Alethocladus is confined to (sub-) Antarctic waters. Future biogeographical and taxonomic research in this brown algal group will need molecular data and methods as well as prolonged research on morphology and life histories. For such a programme availability of living plants in culture is essential.

Key words: Sphacelariales, Phaeophyceae, macroalgae, taxonomy, biogeography