The genus of the family Trypanosomatidae characterized by their being a parasite in the digestive tract of arthopods (mainly insects) and for having an amastigote and choanomastigote developmental stages in their life cycle
The family Trypanosomatidae are comprised of the members referred to as trypanosomatids. They are kinetoplastid protozoa having a single flagellum in which the location may vary depending on the developmental stage. They are parasitic. The genus Crithidia is one of them. The members of this genus are exclusively found in arthropods, primarily insects. There are no known Crithidia species to parasitize humans unlike the other trypanosomid species of the genus Trypanosoma where T. brucei gambiense causes human African trypanosomiasis. Chritidia species are parasites of arthropods, mainly insects. They live in the digestive tract of their host.
Members of the genus Chritidia have two morphological forms (or developmental stages), the amastigote and the choanomastigote forms. In the amastigote stage, these unicellular organisms are lacking the flagellum. In the choanomastigote stage, they develop a single flagellum that emerges to the exterior through a wide funnel- or collar-shaped extension.1
Examples of species belonging to the genus Crithidia are C. bombi (parasitizes bumblebees) and C. mellificae (parasitizes bees).
1 Cheng, T. (1986). General Parasitology. Burlington: Elsevier Science.