A taxonomic study ofEudorina unicocca(Volvocaceae, Chlorophyceae) and related species, based on morphology and molecular phylogeny

Abstract

Colonial volvocacean algae engage in two types of sexual reproduction: isogamy and anisogamy/oogamy with sperm packets. This difference is an important generic diagnosis within the Volvocaceae. Although Yamagishiella differs from the anisogamous genus Eudorina in its isogamous sexual reproduction, the vegetative morphology and asexual reproduction characteristics of the two genera are indistinguishable, especially between Eudorina unicocca G. M. Smith and Yamagishiella unicocca (Rayburn et Starr) Nozaki. We re-examined morphological characteristics of E. unicocca and related species, using multiple strains of E. unicocca and Y. unicocca and molecular phylogenetic analyses. Strains from two Japanese lakes, which produced aplanospores and were solely asexual, could be assigned to either E. unicocca or Y. unicocca, based on traditional morphological diagnoses. However, a new morphological diagnosis (the difference in the distribution and number of contractile vacuoles on the cell surface) and molecular phylogenetic analyses demonstrated that all were E. unicocca. Furthermore, E. unicocca can be divided into two species on the basis of the presence or absence of individual cellular sheaths in the colonial gelatinous matrix, which are observable with methylene blue staining. These two species, E. peripheralis (Goldstein) T. K. Yamada stat. nov. (¼ E. unicocca var. peripherialis Goldstein) and E. unicocca (including the Japanese aplanosporic strains), formed two robust monophyletic groups, based on chloroplast gene sequences for the large RuBisCO subunit and internal transcribed spacer regions of nuclear ribosomal DNA.

An examination of the red algal genus Pugetia (Kallymeniaceae, Gigartinales), with descriptions of Salishia firma gen. & comb. nov., Pugetia cryptica sp. nov. and Beringia wynnei sp. nov.

“…morphological, anatomical, biogeographical, molecular) when describing species or completing monographs (e.g. Schneider & Lane 2008;Yamada et al 2008;Saunders & McDonald 2010). Molecular tools are increasingly being utilized for assigning specimens to genetic species groups from which morphological and anatomical characters can be assessed and for assigning cryptic specimens to known species (e.g.…”

Phylogeny and Molecular Evolution of the Green Algae

“…Molecular phylogenetic analyses of nuclear ribosomal DNA and chloroplast sequences have profoundly changed the concept of the class, which now includes a diverse range of taxa formally placed in the Dunaliellales, Chlorococcales, Tetrasporales, Chlorosarcinales, Volvocales and Chaetophorales Wilcox et al, 1992;Buchheim et al, 1994;Nakayama et al, 1996a;Nakayama et al, 1996b;Booton et al, 1998b;Krienitz et al, 2003;Lewis & McCourt, 2004;Watanabe et al, 2006a;Watanabe et al, 2006b;Nakada et al, 2008a;Nakada et al, 2008b). As presently conceived, the class includes non-motile or motile unicells with two or four flagella, biflagellate colonies, filaments and cells that are imbedded in a mucilage envelope (Nakazawa et al, 2004;Nozaki et al, 2006b;Yamada et al, 2008;Nakada & Nozaki, 2009;Matsuzaki et al, 2010;Novis et al, 2010;Nozaki et al, 2010). The Chlamydomonadales mainly comprise freshwater and terrestrial green algae, including several psychrophilic and/or halotolerant species (e.g., Dunaliella and Chlamydomonas nivalis) (Eddie et al, 2008;Buchheim et al, 2010;Muramoto et al, 2010;Remias et al, 2010).…”

New and rare species of Volvocaceae (Chlorophyta) in the Polish phycoflora

“…Both species are identical in morphological terms. However, in further work Yamada et al [24] report that number and distribution of contractile vacuoles, in all strains of Eudorina and Yamagishiella can be clearly distinguished two genera. Eudorina strains had several contractile vacuoles distributed over the entire surface of vegetative colony protoplasts, whereas Yamagishiella strains had only two contractile vacuoles near the base of the flagella.…”

“…E. unicocca has characteristic gelatinous matrix divided into individual sheath covers of each cell. E. peripheralis differs from E. unicocca in lacking individual sheaths [24]. In disputed species, the gelatinous matrix is not divided, but unfortunately, contractile vacuoles are not visible in the preserved material.…”

“…Gelatinous matrix is homogeneous. Distinction between species Eudorina peripheralis and Yamagishiella unicocca is possible after determine the number and location of contractile vacuoles in the cell [24]. The publication appeared in 2008 year, when most of the presented material was preserved and observation of the vacuoles was impossible.…”