Cylindrocapsa is a genus of green algae, specifically of the Chlorophyceae. It is commonly found in freshwater habitats.
Virus-like particles have been found in a strain of one species, Cylindrocapsa geminella.[1]
Cylindrocapsa consists of unbranched filaments, often attached to substrates or free-floating in water. Cells are initially uniseriate (that is, in one line), but may later become multi-seriate or irregularly arranged. Individual cells are ovoid to oblong to spherical, and are each surrounded by several concentric layers of a mucilaginous sheath. Cells contain a single chloroplast filling the cell, with a single pyrenoid. The chloroplast may be axial (in the middle of the cell) or parietal (lining the wall of the cell).[2]
The placement of Cylindrocapsa is unclear. Species differ significantly from each other, both in terms of morphology and ultrastructure.[2] It is therefore suspected to be polyphyletic.