Figure 6. Hysterocineta bellerophon asser protargol impregnation. A, detail of the anterior body region of the specimen shown in Figure 5A, to document the organization of somatic kineties around the sucker. Skeletal fibres emerge from the anterior end of the less ciliary rows and run almost in parallel with the main body axis. B, detail of the oral ciliary paưern near the entrance to the infundibulum of the specimen shown in Figure 5C. C, D, membranelle M1 and M2 are made up of two rows of basal bodies each, run along the peristome, and terminate near the entrance to the infundibulum. Note that the posterior row of M2 is not recognizable in (C), as it is out of focus. E, F, paroral membrane extends on the opposite side of the infundibulum as M2ʹ and M3, describing 1.5 turns of a spiral. Arrowhead in (F) denotes the anterior end of M2ʹ and M3. G, somatic kineties are composed of narrowly spaced monokinetids. Asterisk marks an irregularity in the somatic ciliary paưern. H, the macronucleus is irregularly curved cylindroidal and contains innumerable small nucleoli. The small anterior blob is a preparation artefact caused by leaked macronuclear material as evidenced by the presence of nucleoli. F, skeletal fibres; M1–3, membranelles 1–3; MA, macronucleus; PM, paroral membrane; S, sucker; SK, somatic kineties. Scale bars = 3 µm (C, D), 10 µm (F, G), 15 µm (B), 20 µm (E, H), 30 µm (A).

Published as part of Obert, Tomáš, Zhang, Tengyue & Vďačný, Peter, 2023, The search finds an end: the morphologically chimeric hysterocinetids belong to the subclass Hymenostomatia (Ciliophora: Oligohymenophorea), pp. 97-123 in Zoological Journal of the Linnean Society 199 (1) on page 107, DOI: 10.1093/zoolinnean/zlad023, http://zenodo.org/record/8326247