Figure 11 in The search finds an end: the morphologically chimeric hysterocinetids belong to the subclass Hymenostomatia (Ciliophora: Oligohymenophorea)

Figure 11. Secondary structure of the 18S rRNA molecule of Hysterocineta bellerophon. Arrows mark molecular synapomorphies of the 'paravorax' clade. Primary nucleotide homologies are scaưered throughout the whole 18S rRNA molecule, suggesting a long common evolution of the 'paravorax' clade. Thus, 'paravorax' clade-specific nucleotide characters are situated in terminal loops of helices (six nucleotide positions), bulges (six positions), single-stranded regions (four positions), and double-stranded regions (32 positions). There are as many as 48 molecular synapomorphies and four indels in the 18S rRNA molecule, corroborating the common origin of hysterocinetids and other members of the 'paravorax' clade. Mutations in the double-stranded regions are typically involved in compensatory base changes or retain helical structure when involved in non-canonical pairings in helices 27 and 43. The 18S secondary structure map of Saccharomyces cerevisiae (inset) is from hưp://apollo.chemistry.gatech.edu/RibosomeGallery.