[ref. ID; 4226 (Richard E. Triemer, 1986)]
Order Euglenida is commonly divided into six suborders. Of these six suborders only two, the Sphenomonadia and the Heteronematina, contain colorless, phagotrophic genera with two emergent flagella. In the Sphenomonadina, the anterior flagellum is characterized as being "straight, not mobile throughout its length during swimming" (Leedale 1967). Secondly, these organisms generally do not possess special ingestion organelles. In contrast to this, the organisms placed in the Heteronematina have special ingestion organelles, a flickering anterior flagellum, and move with a gliding motion.
Genus Peranemopsis, Urceolus, Heteronema, Peranema, Dinema, Serpenomonas