Fig 1.
Morphological observation of field-collected cysts/zygotes of snow-inhabiting Chloromonas.
Identical magnification throughout. For detailed information of collection sites, see S1 Table. (A–C) “C. nivalis zygotes” from site 160518Hk2G1 in Mt. Hakkoda, Japan. (A, B) Light micrographs. (A) Optical section. (B) Surface view, showing a flange (f). (C) Field emission scanning electron micrograph. Abbreviations: lf, long flange (extending the entire cell length); sf, short flange (reaching neither pole of the cell). (D–F) C. miwae cysts from site 130630Gs4G in Mt. Gassan, Japan. (D, E) Light micrographs. (D) Optical section. (E) Surface view, showing flanges (f). (F) Field emission scanning electron micrograph.
Fig 2.
Bayesian phylogenetic tree of snow-inhabiting Chloromonas spp. based on 5,497 base pairs from four genes.
The small subunit and large subunit of rDNA, and the first and second codon positions of atpB and psaB genes were partitioned and unlinked (S4 Table). Specimens of field-collected “C. nivalis zygotes” are underlined. Corresponding posterior probabilities (0.95 or more) are shown at the top left. Numbers shown at the top right, bottom left, and bottom right indicate bootstrap values (50% or more) in the maximum likelihood, maximum parsimony, and neighbor-joining analyses, respectively.
Fig 3.
Bayesian phylogenetic tree of snow-inhabiting Chloromonas spp. based on 340–1,128 base pairs of rbcL.
Each codon position was partitioned and unlinked (S4 Table). Specimens of field-collected “C. nivalis zygotes” are underlined. The operational taxonomic units not included in Fig 2 are highlighted in black. Corresponding posterior probabilities (0.95 or more) are shown at the top left. Numbers shown at the top right, bottom left, and bottom right indicate bootstrap values (50% or more) in the maximum likelihood, maximum parsimony, and neighbor-joining analyses, respectively.
Fig 4.
Comparison of the tip of internal transcribed spacer 2 (ITS2) helix III between MU and Miwa clades.
For the complete ITS2 secondary structures within the MU clade (= C. muramotoi sp. nov.), see S4 Fig. Secondary structures of ITS2 within the Miwa clade (= Chloromonas miwae) are based on previous results [17]. Black backgrounds indicate compensatory base changes between the two clades. Boldfaces marks the YGGY motif.
Fig 5.
Vegetative cells of Chloromonas muramotoi sp. nov.: Line drawings.
Anterior end of the cell is arranged upward. Left, optical section. Right, surface view.
Fig 6.
Vegetative and asexual characteristics of Chloromonas muramotoi sp. nov. strain HkCl-57: Light micrographs.
Identical magnification throughout. Abbreviations: e, eyespot; n, nucleus. (A–D) Vegetative cell. Anterior end of the cell is arranged upward. (A) Optical section. (B) Surface view. (C) Epifluorescence image of (A). (D) Epifluorescence image of (B). (E, F) Asexual reproduction. (E) Just before the first transverse division, showing the position of a parental contractile vacuole (arrow). (F) Autosporangium with eight daughter cells within the parental cell wall (arrowheads).
Fig 7.
Vegetative cells of Chloromonas muramotoi sp. nov. strain HkCl-57: Transmission electron micrographs.
Abbreviations: c, chloroplast; e, eyespot; G, Golgi body; m, mitochondrion; n, nucleus; v, vacuole with crystalline content. (A) Longitudinal cell section. (B) Tangential cell section, showing angular chloroplast profiles. (C) Eyespot composed of a single layer of electron-dense globules.
Table 1.
Vegetative morphological characteristics of five snow-inhabiting Chloromonas species.