| Hydrodictyaceae | |
|---|---|
|   | |
| Pediastrum | |
| Scientific classification   | |
| Kingdom: | Plantae | 
| Division: | Chlorophyta | 
| Class: | Chlorophyceae | 
| Order: | Sphaeropleales | 
| Family: | Hydrodictyaceae Dumortier, 1829 | 
| Genera [1] | |
| See text | |
Hydrodictyaceae is a family of green algae in the order Sphaeropleales. [1] They are found in freshwater habitats worldwide. [2]
Members of this family are either unicellular or colonial. Cells are cylindrical, polyhedral, spherical, or sometimes nearly spherical. Cells contain a single parietal, chloroplast with a pyrenoid. [3] The cell wall may be smooth or covered in warts, ribs or other ornamentation. [4]
Reproduction can occur asexually or sexually. In asexual reproduction, the mother cell becomes a number of zoospores and swim inside the enlarged mother cell wall, until they attach to each other and become a new colony. In Tetraedron , the cells do not produce zoospores but produce autospores within the enlarged mother cell wall. Sexual reproduction, when observed, occurs via isogamous gametes. [2]
Because the cell wall of some Hydrodictyaceae contain sporopollenin, they decay very slowly and thus last long in the fossil record. [5]
 
 The family Hydrodictyaceae includes the following genera: [1]
Traditionally, the genus Tetraedron was excluded and placed within the Chlorellaceae, because of autospore formation. [2] However, the genus produces autospores within an enlarged cell wall, similar to Pediastrum, and molecular phylogenetic evidence shows that they are related. [2]
Molecular phylogenetic studies suggest the following relationships: [2] [6] [7] [8] [9]
| Hydrodictyaceae | 
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| Neochloridaceae (outgroup) | |||||||||||||||||||||||||||||||||||||||||||||||||