PHYLOGENETIC ANALYSIS OF EUDORINA SPECIES (VALVOCACEAE, CHLOROPHYTA) BASED ON RBCL GENE-SEQUENCES

Species and varieties in the genus Eudorina Ehrenberg (Volvocaceae, Ch lorophyta) were evaluated on the basis of phylogenetic analyses of the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rbc L) gene sequence from 14 strains of four Eudorina species, as well as from nine species of Pleodorina and Volvox. The sequence data suggeste d that 10 of the 14 Eudorina strains form three separate and robust mo nophyletic groups within the nonmonophyletic genus Eudorina. The first group comprises ail three strains off. unicocca G. M. Smith; the seco nd group consists of one of the E, elegans Ehrenberg var elegans strai ns, the E. cylindrica Korshikov strain, and both E. illinoisensis (Kof oid) Pascher strains; and the third group consists of two monoecious v arieties off, elegans [two strains of E. elegans var synoica Goldstein and one strain of E. elegans var. carteri (G. hi. Smith) Goldstein]. In addition, E. illinoisensis represents a poly- or paraphyletic speci es within the second group. The remaining four strains, all of which a re assigned to E. elegans var. elegans, are nonmonophyletic. Although their position in the phylogenetic trees is more or less ambiguous, th ey are ancestral to other taxa ill the large anisogamous/oogamous mono phyletic group including Eudorina, Pleodorina, and Volvox (except for sect. Volvox). Thus, the four Eudorina groups resolved in the present molecular phylogeny do not correspond with the species concepts of Eud orina based on vegetative morphology, but they do reflect the results Of the previous intercrossing experiments and modes of monoecious and dioecious sexual reproduction.