Studies on the Sarcomenia group of the Rhodophyta

Abstract

A study of species placed in the genus Sarcomenia, and study of allied genera, shows that Sarcomenia includes one species only. S. delesserioides Sonder. Other species belong either to Platysiphonia Boergesen or to Sarcotrichia gen. nov. The Australian Polysiphonia roeana is shown to belong to the Sarcomenia group and is placed in a new genus, Malaconema. Other related genera which are discussed are Cottoniella Boergesen and Taenioma J . Agardh. C. hawaiiensis Doty & Wainwright is placed in a new genus, Dotyella. These genera form a uniform group, distinguished largely on vegetative features since their reproductive structures are very similar. The Sarcomenia group forms an intermediate and linking group between the Delesseriaceae and Rhodomelaceae, but shows somewhat more features in common with the latter family and may have been derived from rhodomelaceous ancestors. The group is recognized as a subfamily, the Sarcomenioideae, of the Rhodomelaceae, and all other groups of the Rhodomelaceae are considered to form a second subfamily, the Rhodomeloideae. Phylogenetic relationships of the Sarcomenioideae are discussed.