Morphology and phylogeny of a new ciliate, Stentor jiujiangensis sp. nov. (Ciliophora, Heterotrichea)

A new ciliate species, Stentor jiujiangensis sp. nov., discovered in a moss sample from China, is described based on morphological observations of living cells, protargol-impregnated specimens, and small subunit ribosomal DNA (SSU rDNA) sequence data. The new species is distinguished from its congeners by a single spherical to ovoid macronucleus, the presence of yellowish-green cortical granules, and the absence of symbiotic algae. Phylogenetic analyses based on SSU rDNA sequences place S. jiujiangensis sp. nov. within the monophyletic Stentor clade, where it clustered with S. igneus rather than with other species possessing a single compact macronucleus, suggesting that macronuclear morphology is a useful, but not infallible, indicator of phylogenetic relationships within the genus Stentor.