Elliptochloris philistinensis Novis & Visnovsky, 2012

Novis, Phil M. & Visnovsky, Gabriel, 2012, Novel alpine algae from New Zealand: Chlorophyta, Phytotaxa 39, pp. 1-30 : 24-25

Elliptochloris philistinensis Novis & Visnovsky , sp. nov. ( Figs 6A–B )

Cellulae juvenes cylindrico-ellipsoidales, 6.2–7.7 µm longae, 3.1–4.6 µm latae, aetate ellipsoideae vel sphaericae, usque ad 8.5 µm latae, unicae vel in greges aggregatae, cytoplasma vesiculis tribus vel pluribus instructa (ut videtur materiam lipidicam includentibus) continentes. Paries cellularis tenuis laevisque. Chloroplastus viridis , parietalis, cupulatus, pyrenoidem unicam per vagina valde segmentata amylacea circumdatam continens. Matrix pyrenoidis thylacoidibus pluribus penetrata sed forma non distincta. Autosporis 2–4 per sporangium regenerans.

Type:— NEW ZEALAND: Westland : Mt Philistine, 1400 m, preserved cultured specimen from sample collected 30 November 2007, CHR610490 .

Young cells cylindrical–ellipsoidal, 6.2–7.7 µm long, 3.1–4.6 µm wide, becoming ellipsoidal to spherical with age, up to 8.5 µm wide, singly or in groups, containing 3–numerous vesicles in cytoplasm (thought to contain lipid; Fig. 5A ). Cell wall thin and smooth. Chloroplast green, parietal, cup-shaped, with single pyrenoid surrounded by highly segmented starch sheath ( Fig. 5B ). Pyrenoid matrix penetrated by several thylakoids, but pattern indistinct. Reproduction by autospores, 2–4 per sporangium. Sequence data for the 18S rDNA gene placed E. philistinensis robustly in a clade of Elliptochloris species , but separated from others by a moderately long branch emerging at the first node ( Fig. 8 ).

Habitat:— Alpine herbfield soil.

Distribution:— New Zealand.

Etymology:— Referring to Mt Philistine, the site of collection.

Observations:— Elliptochloris represents a well-defined genus in the Trebouxiophyceae. The pyrenoid of E. marina Letsch et al. 2009 is described as a “thylakoid free region” in the chloroplast, and appears similar to our observations. One other species, E. subsphaerica (Reisigl) Ettl & Gärtner (1995) has a pyrenoid, but this is clearly distinguished from E. philistinensis by young cells that are frequently curved, and by molecular data ( Fig. 8 ).

Cultures:— LCR-CG5.

Figures

FIGURE 5. Variochloris pyrenoglobularis (photographed from culture LCR-CG2). A–D light micrographs, E, F, transmission electron micrographs. A. Large mature cells with granular contents and pyrenoids (pyr). B. Younger cells of smaller size, and autosporangia. C. Autosporangia (arrows) containing two and four daughter cells. D. A cell cluster including one cell with a dividing chloroplast (arrow), preliminary to cytokinesis. E. Sectioned autospores in sporangium, showing looped thylakoids (tm) intruding into pyrenoid matrix from periphery. F. Higher magnification view of pyrenoid matrix and starch plates (sp), showing pyrenoglobuli (pg) surrounding the thylakoid loops. Scales: 10 µm in A (use for A–D), 1 µm in E and F.

FIGURE 6. Elliptochloris philistinensis (photographed from culture LCR-CG5). A. Light micrograph showing cylindrical– ellipsoidal young cells and several near-spherical mature cells (arrows). Cells contain many vesicles (v), thought to contain lipid. B. Section through an autosporangium, showing daughter cells with chloroplasts containing starch (st) and prominent pyrenoids (pyr) surrounded by starch plates (sp). The pyrenoid matrix is fairly homogeneous. Vesicles (v) thought to contain lipid are visible, and a nucleus (nuc) in one of the cells. Scales: 10 µm in A, 1 µm in B.

FIGURE 8. Phylogenetic analysis of the Trebouxiophyceae inferred from 18S rDNA sequences. Sequences contributed in this study are in bold. The tree typology is that inferred using MrBayes v3.0B4 (5 million generations). Numbers associated with nodes are Bayesian PP/MPB percentages (500 replicates). Scale bar represents 0.1 changes/site.