Oocystaceae


Oocystaceae is a family of green algae, in the class Trebouxiophyceae. Molecular phylogenetic studies mostly place the family in the order Chlorellales, as sister to Chlorellaceae. The type genus is Oocystis.
Members of Oocystaceae are common microalgae in freshwater habitats, and a few occur in semi-saline.

Description

Members of the family Oocystaceae consist of cells which are solitary or found in colonies of 2, 4, 8, 16, or more. Cells are typically oval to ellipsoidal, sometimes spherical, rhomboid, spindle-shaped or lemon-shaped. Cells, when colonial, may be arranged into coenobia or pseudofilaments. Cells contain multiple chloroplasts of varying morphology—usually parietal, sometimes radial or spongiform, and with or without a pyrenoid. The cell wall is multilayered, often thickened at the poles, and may be smooth, warty or covered in spines.
A uniting ultrastructural feature of all members of this family is the multiple-layered cell wall, with the cellulose fibrils in each layer organized perpendicularly to those of adjoining layers.
Reproduction occurs asexually and via the production of multiple autospores. The daughter cells often remain in the expanded mother cell wall.

Classification

Traditionally, genera and species within Oocystaceae have been separated from each other based on morphology. However, microalgae typically have very few morphological features for classification, and the morphological features may have evolved more than once. Currently, molecular phylogenetics form the basis of species and genera.
Morphologically, there were three subfamilies: Eremosphaeroideae, Lagerheimioideae and Oocystoideae. Molecular data has revised this to the three current subfamilies: Eremosphaeroideae, Makinoelloideae, and Oocystoideae.

List of genera

, AlgaeBase accepted the following genera:
Phylogenetic studies suggest the following relationships :
The genera Tetrastrum and Planctonema are incertae sedis taxa: they are sister to the rest of Oocystaceae and may be classified as such, but do not show the characteristic ultrastructure of Oocystaceae.