The 33 strains identified as Heterococcus used in this study. The Heterococcus strains are listed with their species names (where provided) from previous morphological analyses, their assignment to clades and lineages in the rbcL phylogeny (boxed with thick lines; see Figure 3), their assignments to a certain species recognized in this study (boxed with thin lines), their new species designations (see Discussion) and their geographic origin. Highlighted in green are genotypes, i.e. groups of strains exhibiting high sequence similarities (see text). Strains in bold letters represent cryopreserved epitypes (reference strains) designated for each species (see Discussion). An asterisk marks an authentic reference strain (see text). a marks those strains that have recently been isolated by us or were provided to us for this study; n.a.1, not applicable because the psbA/rbcL spacer sequence could not be determined (see text); n.a.2, not applicable because strains were identified as green algae (see text).