Observations on the Proboscis‐Cytopharynx Complex and Flagella of <i>Rhynchomonas metabolita</i> Pshenin, 1964 (Zoomastigophorea: Bodonidae)*

Abstract

SYNOPSIS. The description of Rhynchomonas metabolita is amended on the basis of new electronmicroscopic and other evidence. The proboscis of R. metabolita is not derived from the anterior flagellum, but rather is an outward extension of the cytopharynx. Food organisms are taken up near the distal tip of the proboscis and pass through a membrane‐limited lumen continuous with the permanent cytopharynx. The cytopharynx‐proboscis lumen is surrounded by overlapping rows of microtubules running parallel to the long axis of the lumen; these may be involved in the accommodation of food particles that are larger than the resting diameter of the lumen. R. metabolita has 2 emergent flagella, the previously described trailing flagellum and a hitherto unreported shorter anterior flagellum that is closely associated with the proboscis; the anterior flagellum and proboscis normally beat synchronously. A paraxial rod is present in both flagella. Rhynchobodo Lackey, 1940 is probably a synonym of Rhynchomonas.