''Tetradesmus lagerheimii'' is a

green alga 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 Scenedesmaceae is a family of green algae in the order Sphaeropleales. ''Scenedesmus'' algae are commonly found in freshwater plankton. The former family Coelastraceae is considered a synonym of Scenedesmaceae. The family has existed since at ...

. It is also known by its synonym, ''Scenedesmus acuminatus''. ''Tetradesmus lagerheimii'' forms colonies of two, four or eight cells in a single row, with cells arranged linearly or in a somewhat zig-zag fashion. The colony is typically curved, semicircular, or contorted. Cells are spindle-shaped, arc-like, or sigmoid, 9.2–34.5(–40) μm long and 2–5.5 μm wide; the outermost side is concave; both ends taper to a point. It is a very common species, and is found in a variety of freshwater habitats.

References

Sphaeropleales Chlorophyta species {{Chlorophyceae-stub