Morphology and morphogenesis of the hypotrich ciliate Parentocirrus hortualis Voβ, 1997, with notes on the phylogeny of Parentocirrus (Ciliophora, Hypotrichia)

The morphology, morphogenesis and molecular phylogeny of the hypotrich ciliate Parentocirrus hortualis, isolated from soil in northwestern China, was studied using live observation and protargol staining. The Chinese population closely matches the German type population although some features such as the number of macronuclear nodules (4–8 vs 5–16) and transverse cirri (4 or 5 vs 2–4) differ considerably. These differences can probably be explained, at least in part, by environmental adaptability. We also compared the ontogenetic processes in the two populations and did not find any significant differences. Phylogenetic analyses based on SSU rDNA gene sequence data showed that Parentocirrus hortualis clusters with Gastrostyla steinii and Parentocirrus sp., which together form a clade with another species of Gastrostyla within the Stylonychinae. These findings suggest that Parentocirrus and Gastrostyla are closely related.