Spironematellidae (previously known as Spironemidae) is a family of heterotrophic flagellates, in the group Hemimastigophora. They vary in size and shape from the ellipsoid Hemimastix amphikineta (14 à7 üm) to the vermiform Spironematella terricola (43 à3 üm), and are united by the possession of two rows of cilia, called kineties.
Phylogenomic analysis shows that Hemimastigophora are a distinct and ancient lineage of eukaryotic organisms, forming a possible sister clade to the supergroup Diaphoretickes.
The classification of Spironematellidae, as of 2022: