See text Hydrodictyaceae is a family of green algae in the order Sphaeropleales.

[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 (not all genera are included):[2][6][7][8] Pediastrum Hydrodictyon Pseudopediastrum Monactinus Lacunastrum Stauridium Parapediastrum Sorastrum Tetraedron Neochloridaceae (outgroup)