Phylogenetic position of Volvox rousseletii originating from Japan (Table 1) within Volvox sect.

Volvox, based on maximum likelihood (ML) analysis of combined data matrix of rbcL and psbC gene sequences. Colemanosphaera and Platydorina constitute outgroup. Branch lengths are proportional to the evolutionary distances that are indicated by the sale bar. Numbers in left and right sides at branches represent bootstrap values (50% or more) based on 1000 replications of ML and posterior probabilities (0.85 or more) by Bayesian inference, respectively.