Spironematellidae

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 × 7 μm) to the vermiform Spironematella terricola (43 × 3 μm), 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.