Table 2 Morphometric and morphological characteristics of the TAU-MAC strains isolated from freshwaters in Greece

0910, 1010

Colonial green algae having flat colonies that consist of two or four cells linearly arranged along their long axes. Four-celled coenobia most frequent, but also two-celled and eight-celled were observed. Cell dimensions 8–14 µm long and 3–7 µm wide with one big pyrenoid, short subpolar spines and small lateral. Ribs and rosettes present. Asexual reproduction by aplanosporogenesis

1a–f

Desmodesmus sp.

0810, 3110

Cells ovoid and elongated, slightly larger and more elongated in 0810 than in 3110, with one clearly visible pyrenoid surrounded by a sheath of starch plates. The ellipsoidal cells had dimensions 3–9 × 2–6 μm (0810) and 2–7 × 2–5 μm (3110). The single, spineless cells were dominant in 0810 isolate. The rare four-celled coenobia were always spined with two polar and one lateral spine in the outer cells. Two-celled coenobia were the most frequent in 3110 isolate and less commonly four-celled linearly arranged along their long axes. The coenobia had two polar spines in each outer cell, rarely lateral spines were observed. Single cells often had two polar spines. Reproduction by autospores produced by longitudinal division, two to eight per sporangium

1g–k

Desmodesmus abundans

2810

Cells ovoid with single large pyrenoid. The two-celled coenobia were common, but four-celled coenobia were predominant and always with lateral spines both in outer and inner cells. Cell dimension 5–13 µm long and 3–7 µm wide. Asexual reproduction by aplanosporogenesis

1l, m

Desmodesmus subspicatus

3410

Ellipsoidal cells (11–21 µm long and 3.4–9 µm wide); coenobia linearly arranged with one big pyrenoid per cell covered with starch envelope. The dominant four-celled and rare eight-celled coenobia were always spined with one spine at each pole of outer cells. The entire coenobium was surrounded by an outermost cell wall layer which is visible between poles of inner cells of coenobia. Coenobia with lateral spines in inner cells ware observed very rarely. Asexual reproduction by division of mother cell into 4 daughter cells

1n, o

Desmodesmus communis

0215

Filaments unbranched and indefinite in length. Cells are cylindrical, elongated, closely adherent to one another, uninucleate. Cell diameter increases with the age of a filament from 4 to 10 μm and 7 to 23 μm long, containing more than one pyrenoid. Most of the filaments possess a pointed apical cell at the free end which exhibit a different degree of tapering (acuminate, apiculate or attenuate) and a holdfast for attachment by means of a modified basal cell. The morphology of the holdfast also varies from small and colorless to massive and dark brownish-red. The unbranched filaments may undergo fragmentation. Asexual reproduction takes place by aplanosporogenesis or zoosporogenesis

2a–h

Uronema sp.

1110, 3210

Cells always spherical and microscopic, 3–9 μm in diameter with one large pyrenoid. Young cells ellipsoidal, becoming spherical at maturity. Reproduction by autosporogenesis usually two autospores per sporangium

2i–n

Chlorella vulgaris

3310

Ellipsoidal to spherical solitary young cells 4–9 µm in diameter. Each young cell contains one relatively big nucleus and one pyrenoid covered with starch envelope. Mature cells ovoid to irregular in shape, 19 µm in max. dimension, organized into dyads, tetrads, or packets resulting from desmoschisis. Mature cells remain uninucleate, possessing one to four pyrenoids. Asexual reproduction performed by desmoschisis or zoospores and aplanospores

2o–r

Spongiosarcinopsis sp.

3510

Solitary vegetative cells spherical to irregular form, 7–13 μm diameter with the ability to form cell aggregates. One or several pyrenoids, single nucleus or multiple nuclei directly before reproduction by aplanospores. Flagella not visible under the light microscope. Asexual reproduction by aplanospores

2s–v

Chlamydomonadales sp.