Redescription of Pseudovorticella cylindrica (Dons, 1915) nov. comb. and Zoothamnium hiketes Precht, 1935, two poorly defined marine peritrichs (Ciliophora: Peritrichia) from the north China Sea

Abstract

The living morphology, silverline system and infraciliature of two marine peritrichous ciliates, Pseudovorticella cylindrica (Dons, 1915) nov. comb. (formerly Vorticella cylindrica) and Zoothamnium hiketes Precht, 1935, collected in Qingdao, China, were investigated. Based on the Qingdao populations, both species are redefined. Pseudovorticella cylindrica is characterized by: cell inverted bell‐shaped, about 45×50 µm in vivo; macronucleus J‐shaped; one apically positioned contractile vacuole; pellicle smooth with inconspicuous, closely spaced striations; the number of transverse silverlines from peristome to aboral ciliary wreath 33–40, from aboral ciliary wreath to scopula 14–19; the inner row of peniculus 3 conspicuously short. An updated and supplementary description of Zoothamnium hiketes is also supplied: size of zooid in vivo 70×35 µm on average, elongate in shape with inconspicuously double‐layered peristomial lip; macronucleus C‐formed; one large contractile vacuole apically located; colony dichotomously branched; the number of striations from peristome to aboral ciliary wreath 89–109, from aboral ciliary wreath to scopula 35–43; rows in peniculus 3 parallel to each other.