Systematics and biogeography of the Compsopogonales (Rhodophyta) with emphasis on the freshwater families in North America

The red algal order Compsopogonales sensu lato, including the Boldiaceae, Compsopogonaceae, and Erythrotrichiaeae, is supported as a valid taxonomic entity through phylogenetic analysis of gene sequence data (18S rRNA, rbcL, and combined analyses). A well-defined freshwater lineage was identified in these analyses, and a close relationship was recognized between the Boldiaceae and the Compsopogonaceae. Biogeographic distribution of the Boldiaceae and Compsopogonaceae in North America was assessed using gene sequence data from the 5.8S rRNA gene and the flanking internally transcribed spacer regions (ITS1 and ITS2). Analysis of the Boldiaceae indicates that introductions have occurred from southern populations into northern areas. No obvious geographic trend was evident in the Compsopogonaceae. The sequence data support the Compsopogonaceae as being monotypic in North America, comprising the single species, Compsopogon coeruleus (Balbis) Montagne.