Description of Zoothamnium foissneri n. sp. and redescription of Z. duplicatum Kahl, 1933 and Z. mucedo Entz, 1884, three species of marine peritrichous ciliates

Three marine peritrichs, Zoothamnium foissneri n. sp., Z. duplicatum Kahl, 1933 and Z. mucedo Entz, 1884, were isolated from the littoral area of Qingdao, China. The morphology, infraciliature and silverline system were studied on living and silver-impregnated specimens. Z. foissneri is distinguished from congeners by its slender zooid shape, size, appearance of peristomial border, the form of peniculus 3, colony form and habitat. Based on the Qingdao populations, supplementary information is given for two known species showing that Z. duplicatum can be distinguished by the zooid shape and size, the number of silverlines between the aboral trochal band and the scopula, and the form of peniculus 3, while Z. mucedo can be distinguished from other species of similar zooid shape and size by the form of peniculus 3 and the number of silverlines between the oral area and the aboral trochal band.