Identification and phylogenetic relationships within the genus Tetrahymena using the cytochrome c oxidase subunit 1 gene and the small subunit ribosomal RNA gene

Nucleotide sequences of the mitochondrial cytochrome 'c' oxidase subunit 1 ('cox1') gene were used as a "DNA barcode" to identify the closely related species of the ciliate genus 'Tetrahymena ' and 3 other tetrahymenine species. Except for 'Tetrahymena furgasoni, Tetrahymena lwoffi, Tetrahymena pyriformis', and ' Tetrahymena setosa', all isolates could be identified to the species level using 689 bp of the 'cox1' sequences. Intraspecific isolates of 'Tetrahymena borealis, T. lwoffi, Tetrahymena patula', and ' Tetrahymena thermophila' could be discriminated and identified by their 'cox1' sequences as shown by