Figure 1.

Maximum likelihood tree inferred from 18S rRNA gene sequences of various trebouxiophycean algae. The chlorophytes Scenedesmus communis and Chlamydomonas reinhardtii were used as outgroups. Bootstrap support of respectively maximum parsimony, neighbor joining, and maximum likelihood analyses is shown along nodes if > 50%. Branch lengths are proportional to the number of substitutions/site (note scale bar). Sequences determined in this work are encircled. Reference sequences were taken from GenBank and are identified by their accession number.