Trypomastigote

Trypomastigote is an extracellular "non-replicative" form of a parasite. It is a leaf-like form with undulating membrane and flagellum that emerges through a flagellar pocket and runs the whole length of the cell. A large kinetoplast is found at the base of the flagellum; i.e., posterior end of the cell. Trypomastigote is found in the bloodstream of infected vertebrate host.

Seen in Trypanosoma cruzi and Trypanosoma brucei. Can be either metacyclic in T. cruzi, or procyclic and bloodstream form in T. brucei.

Reference:

1) http://dna.kdna.ucla.edu/parasite_course-old/Default.aspx