Chilomastix are retortamonad flagellates that have a pyriform and twisted cell body of about 20 µm in length with three anteriorly directed flagella and one short recurrent flagellum beating inside a ventral cytostomal pocket. The right fibril bordering the cytostomal pocket is thicker and forms a hook at its posterior end where food is phagocytosed. Cysts are pyriform and retain the internalised cytostomal fibers. They live in anoxic habitats but one species C. cuspidata is free-living. Among the 29 or so parasitic or endocommensal species described many live in the gut of vertebrates - such as C. mesnili in man and some in the gut of invertebrates such as C. aulastomi from the leech Aulastoma gulo. This species, Chilomastix caulleryi, is from the intestine of amphibia (haematoxylin staining).
