Chlorellales

Muelas del Pan, Castille and Leon, Spain

Caada del Hoyo, Castilla-La Mancha, Espaa

Caada del Hoyo, Castilla-La Mancha, Espaa

Melgar de Tera, Castille and Leon, Spain

Ribadelago de Franco, Castilla y Len, Espaa

Micractinium pusillum (Fresenius,1858). Usually found in four-celled colonies (only three of the four cells of this colony are seen here). Each cell has two to seven long, delicate setae. Each cell has one cup-shaped plastid with a pyrenoid. 18S ribosomal RNA gene studies place this genus in the Trebouxiophyceae. One of the distinguishing features of trebouxiophytes is metacentric mitosis in which centrioles are located near the metaphase plate of the chromosomes rather than at the spindle poles. Other characteristics include formation of microtubules parallel to the dividing cell wall during cytokinesis (phycoplast). The similar genus, Errerella, has only one spine per cell.Collected from a freshwater pond near Boise, Idaho. July 2005. Phase contrast.

Portrait of the planktonic trebouxiophyte alga, Tetrastrum staurogeniaeforme (Schröder) Lemmermann.The colonies consist of four ellipsoid cells with four to six short spinous projections from the each cell surface. several four-celled colonies may join together to form compound colonie (compound coenobia). Each cell has one plastid and one pyrenoid.Collected from a freshwater pond near Boise,Idaho. July 2005.DIC.

Green algae live in a mucus ball. Phase contrast microscopy.

Chlorella (clo-rell-a), tentatively identified as such. The genus contains solitary green algal cells without flagella. Phase contrast.

Chlorella ( Beijerinck, 1890) from the cytoplasm of a burst Frontonia cell in which they had been living as symbionts.DIC.

Portrait of Dictyosphaerium pulchellum (Nägeli,1849), a colonial green alga. The small cells are ovoid to reniform and are borne at the ends of colorless branching threads in groups of four. The threads are remnants of parental cell walls. Each cell has a cup-shaped chloroplast and solitary pyrenoid.The entire colony is embedded in a nearly invisible spherical gelatinous matrix. Collected from a freshwater pond near Boise, Idaho June 2004. DIC optics.

Portrait of Dictyosphaerium pulchellum (Nägeli,1849), a colonial green alga. The small cells are ovoid to reniform and are borne at the ends of colorless branching threads in groups of four. The threads are remnants of parental cell walls. Each cell has a cup-shaped chloroplast and solitary pyrenoid.The entire colony is embedded in a nearly invisible spherical gelatinous matrix. Collected from a freshwater pond near Boise, Idaho June 2004. DIC optics.

Dictyosphaerium pulchellum is a common chlorophyte of Lake Kinneret, relatively more abundant in winter, but never dominant. This specimen was sampled at the shore of the lake in March 2006.

Dictyosphaerium pulchellum is a common chlorophyte (Chlorococcales) of Lake Kinneret, relatively more abundant in winter, never abundant or dominant. Note that the sphaerical cells are in clusters of 4, attached by parental cell wall fragments radiating from a common center. The chloroplasts are parietal and cup shaped with a single pyrenoid. This specimen was sampled at the shore of the lake in March 2006.

Portrait of the nonmotile green alga, Franceia droescheri (Lemmermann, 1898). The cell is ovoid with a thin inflexible cell wall. Usually solitary but may be found in small colonies embedded in a gelatinous matrix.Long fine slightly tapered spinous projections are randomly distributed over the entire cell surface. The otherwise identical Chodatella ciliata has spines lacalized to the poles of the cell. F. droescheri has one to three parietal chloroplasts eache with a pyrenoid.The nucleus is not well seen in this image. Collected from freshwater pond near Boise, Idaho December 2003. DIC optics.

Chodatella citriformis containing 8 autospores, sampled from shore water of Lake Kinneret in March 2006. This Chlorophyte (Chlorococcales) can be found in the plankton of the lake at most times of the year, particularly in May-June, but is never dominant.

Portrait of the planktonic trebouxiophyte alga,Chodatella wratislaviensis (Schröder) Ley,1948.The ellipsoid cells are solitary.There are four slightly curved tapering spines each with a button-like base. two are polar and two equatorial.There is a single parietal chloroplast and a pyrenoid.Collected from a freshwater pond near Boise,Idaho(43°37'03.94"N 116°11'07.62"W elev. 2754 ft.)  November 2005.DIC