Figure 6

Transmission electron micrographs (TEM) of non-consecutive serial sections through the flagellar apparatus and feeding pockets of Bihospites bacati n. gen. et sp. TEMs taken at levels posterior to those shown in Figure 5 and presented from anterior (A) to posterior (D). A. TEM showing the posterior end of the main C-shaped rod (r) embedded in an amorphous matrix (double arrowhead) and surrounded by a thick membrane with fuzzy material (arrowhead). At this level, the rod is associated with 'congregated globular structure' (CGS), and the striated fibres that form the accessory rod (ar) appear near the cytostomal funnel (cyt) at the junction between the feeding pocket and the flagellar pocket. Inset: TEM showing the accessory rod (ar) in a subsequent posterior section, as it starts to open up. Vf = ventral flagellum; Df = dorsal lagellum. B. TEM showing the separation (arrowhead) of the feeding pocket (asterisks) from the flagellar pocket (FP) near cytostomal funnel (cyt) and the expanding accessory rod (ar). C. TEM showing the diminishing feeding pocket (asterisks), the cytostomal funnel (cyt), and the separate flagellar pocket (FP). D. TEM showing the accessory rod (ar) with its characteristically folded shape becoming more tightly linked to the main rod (r). Lobes of the feeding pocket (asterisk) and the flagellar pocket (FP) are also still visible. MtD = mitochondrion-derived organelle; double arrowheads = spherical-shaped episymbionts. (bars = 2 μm).