Morphological and Molecular Identification of a New Ciliate, Zoothamnium palmphlatum nov. spec. (Ciliophora, Peritrichia) from North China.

A new peritrichous ciliate, Zoothamnium palmphlatum nov. spec., was collected from an estuary in Yantai, China. It was investigated, using both live observation and silver staining. The new species can be identified by a palm-shaped colony consisting of highly developed and alternately arranged secondary branches, a double-layered peristomial lip, and an infundibular polykinety 3 composed of two parallel kinetosomal rows. Phylogenetic analyses of the small subunit (SSU) rRNA gene sequence show that Z. palmphlatum clusters with other members of the family Zoothamniidae. Furthermore, the comparison of primary and secondary SSU rDNA structures indicates that Z. palmphlatum is distinctly different from its morphologically similar species (93.2-97.0% in sequence similarity) in combination of H10 and H31 regions. Although Z. palmphlatum shares highest sequence similarity with Zoothamnium mucedo (98.9%), the new species has distinctly different structures in the H11, H12, H18, and H31 regions compared to Z. mucedo, which indicates that sequence similarity may not determine the similarity of the secondary structure.