Chlamydomonas schloesseri Pröschold & Darienko, 2018

Pröschold, Thomas, Darienko, Tatyana, Krienitz, Lothar & Coleman, Annette W., 2018, Chlamydomonas schloesseri sp. nov. (Chlamydophyceae, Chlorophyta) revealed by morphology, autolysin cross experiments, and multiple gene analyses, Phytotaxa 362 (1), pp. 21-38 : 25-26

Chlamydomonas schloesseri Pröschold & Darienko sp. nov. ( Fig. 1 )

Diagnosis: Mature vegetative cells are spherical, broadly ellipsoidal, ovoid or sometimes obovoid 8.7 x 9.3 to 9.6 x 11.9 μm in size. Cell wall is thin, without papilla, two apical contractile vacuoles. Chloroplast is cup-shaped, with thickened basal part. The surface of chloroplast is smooth, sometimes small incisions could be observed. The single pyrenoid is medium large, spherical or broadly ellipsoidal, surrounded by several starch grains and placed in the thick part of chloroplast. Nucleus is placed in the anterior part of cell. Eyespot is small, dot-like, anterior to equator. Protoplast is often withdrawn from the cell wall. The vegetative cells (flagellated and immobile) are surrounded by layered mucilage and frequently immobile. Asexual reproduction by zoospores formation. Zoosporangia contain mostly 2–8, rarely 16 zoospores, and are 13.3–22.7 μm in diameter. The morphology of zoospores is similar to that of the vegetative cells. Sexual reproduction not observed.

Differs from C. gelatinosa Korshikov ex Pascher by smaller cell size and thinner mucilage layer surrounding the vegetative cells.

Type locality: Rhinopool in the Lake Nakuru National Park, Kenya.

Holotype (designated herein): The strain SAG 2485 is permanently cryopreserved in a metabolically inactive state (cryopreserved in liquid nitrogen) in the SAG, University of Göttingen , Germany.

Iconotype (designated herein in support of the holotype): Fig. 1A in this study.

ITS-2 DNA Barcode: BC 1 in Fig. 7 .

Etymology: The species was named in honor of Prof. Dr. Uwe Gert Schlösser for his contribution to phycology and his further development of the Culture Collection of Algae, University of Göttingen (SAG).

The three investigated strains are morphologically identical and differ mainly from other closely related species by the presence of mucilage surrounding the vegetative cells in C. schloesseri . The diacritical morphological features of the three Chlamydomonas species are summarized in Table 1. As shown in Table S1, all strains designated as C. reinhardtii and C. smithii (authentic strain SAG 54.72) were identified as C. reinhardtii using the identification keys of Ettl (1976, 1983). The three strains SAG 81.72, SAG 7.73 and NIES-2462 matched in morphology with original description of Pascher (1927) for C. incerta and the diagnoses provided by Ettl (1965, 1976). The strains of C. schloesseri were identified as C. gelatinosa using the keys of Ettl, but the comparison with original descriptions of this species by Korshikov in Pascher (1927) and Korshikov (1938) showed clear differences in morphology. The vegetative cells of C. gelatinosa have another cell shape (broadly ellipsoid) and size (12–20 μm x 6–10 μm) and the mucilage surrounding the cells is up to 6 μm thick.

Figures

FIGURE 1. Morphology and phenotypic plasticity of Chlamydomonas schloesseri sp. nov. A–J. vegetative cells, arrow in F. marked the eyespot; K–O. different sporangia; scale bar = 10 μm.

FIGURE 7. Comparison of the conserved region of ITS-2 among the species of Chlamydomonas. Extraction of this region and translation into a number code for its usage as barcode (extracted bases highlighted with an asterisk). Number code for each base pair: 1 = A-U; 2 = U-A; 3 = G-C; 4 = C-G; 5 = G•U; 6 = U•G; 7 = mismatch.