''Westella'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

green algae The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...

in the family Scenedesmaceae, containing the sole species ''Westella botryoides''. The species has a

cosmopolitan distribution In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en ...

and is

planktonic Plankton are the diverse collection of organisms that drift in water (or air) but are unable to actively propel themselves against currents (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they pro ...

in freshwater rivers and ponds. ''Westella botryoides'' consists of four-celled colonies (termed coenobia) up to 15 μm; these in turn may be joined to form compound colonies consisting of over a hundred cells and reaching up to 90 μm, attached to each other by the remnants of their parental

cell wall A cell wall is a structural layer that surrounds some Cell type, cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, ...

s. The four cells are typically arranged in a square, spherical but flattened when in contact with other cells. The cell walls are smooth; cells are uninucleate with a single, parietal

chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

containing one

pyrenoid Pyrenoids are sub-cellular phase-separated micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. ''An ...

. Two similar genera are '' Westellopsis'' and '' Coccoidesmus''. ''Westellopsis'' differs in having chloroplasts without pyrenoids and usually cells arranged in a line, while ''Coccoidesmus'' has cells arranged in a tetrahedral formation.

References

Sphaeropleales genera Sphaeropleales Freshwater algae Monotypic algae genera {{Chlorophyceae-stub