Report and Phylogeny of a Novel Euplotes Species from China: E. mazeii n. sp., and Review of E. balteatus (Alveolata, Ciliophora)

The freshwater species, Euplotes mazeii n. sp., and the marine species, E. balteatus (Dujardin, 1841) Diesing, 1850 were collected from China and investigated based on their living morphology, ciliary pattern, and small subunit ribosomal RNA (SSU rRNA) gene sequence data. Euplotes mazeii n. sp. was characterized by its small cell size ((40 – 55) μm × (25 – 35) μm), nine frontoventral cirri, one marginal and two caudal cirri, seven dorsal kineties, and a double-eurystomus type of dorsal silverline system. Phylogenetic analyses based on molecular data confirmed the branching position of this new taxa within the genus Euplotes, with 5.01% (84 nucleotides) sequence variation, supporting the identification of a new species. We re-examined all described and supposedly conspecific populations and give a review of Euplotes balteatus. E. balteatus has been reported frequently; however, E. balteatus sensu Agamaliev, 1968 is different from other populations in the number of marginal cirri or the type of silverline system, which suggests there might be a misidentification. The SSU rRNA gene sequences of two populations of E. balteatus from the studies of Chen et al. (2013) and Pan et al. (2012) differ from each other by more than 135 nucleotides, implying that the identity of the species currently associated with the SSU rRNA gene sequence in molecular databases requires further confirmation.