The Ultrastructure of Zosterodasys agamalievi (Ciliophora: Synhymeniida)

The cell surface of the synhymeniid ciliate, Zosterodasys agamalievi, consists of shallow kinetal grooves separated by low cortical ridges. Numerous electron‐opaque bodies are located in the cortical ridges, inside the kinetal grooves, and are distributed in parallel rows between adjacent kineties. Well‐developed alveoli are present beneath the cell surface membrane. Zosterodasys agamalievi has a single micronucleus and a homomerous macronucleus. The infraciliature of the somatic monokinetid consists of an anteriorly‐directed kinetodesmal fiber, a well‐developed divergent postciliary microtubular ribbon, radially‐oriented transverse microtubules, and a short striated rootlet, which extends anteriorly from the base of the kinetosome into the cell. Zosterodasys agamalievi has a perioral band of paired cilia, the synhymenium, that winds obliquely across the ventral surface of the body, just posterior to the cytostome. The infraciliature of the anterior kinetosome of the synhymenium consists of two postciliary microtubules; a well‐developed, divergent post‐ciliary ribbon of microtubules and a short kinetodesmal fiber are associated with the posterior kinetosome. The cytopharynx is supported by 14‐16 nematodesmata which are capped distally by a capitulum. The cytopharynx is bound proximally by a fibrous sheath and is lined by radially‐arranged microtubular ribbons. No obvious oral ciliature is present.