First record of Paramecium pentaurelia (Ciliophora) from Japan

Two new Paramecium strains were isolated from an artificial pond on a university campus located in Tokyo, Japan. Morphological observations and molecular phylogenetic analyses based on partial sequences of heat shock protein 70 and cytochrome b gene sequences identified both strains as Paramecium pentaurelia , one of the sibling species within the Paramecium aurelia species complex. This represents the first confirmed record of P . pentaurelia in Japan. Although this species has rarely been reported on a worldwide basis, the phylogenetic analyses showed that the Japanese strains shared identical or nearly identical sequences with multiple P . pentaurelia strains from geographically distant regions, suggesting that this species may have a wider, possibly cosmopolitan, distribution than has currently been recognised. The limited number of records may reflect the infrequent occurrence of this species in environmental samples, which may hinder its detection.